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  • 1.
    Abdel–Khalik, Jonas
    et al.
    Storbritannien.
    Björklund, Erland
    Kristianstad University, School of Education and Environment, Avdelningen för Naturvetenskap. Kristianstad University, Plattformen för molekylär analys. Kristianstad University, Faculty of Natural Science, Avdelningen för miljö- och biovetenskap. Kristianstad University, Faculty of Natural Science, Research environment MoLab.
    Hansen, Martin
    USA.
    Development of a solid phase extraction method for the simultaneous determination of steroid hormones in H295R cell line using liquid chromatography–tandem mass spectrometry2013In: Journal of chromatography. B, ISSN 1570-0232, E-ISSN 1873-376X, Vol. 935, no September, p. 61-69Article in journal (Refereed)
    Abstract [en]

    The H295R in vitro cell line produces the majority of the steroidogenesis, for which reason it is commonly used as a screening tool for endocrine disrupting chemicals. Simultaneous determination of the precursor cholesterol and key steroid hormones could give a broad insight into the mechanistic disruption of the steroidogenesis. Steroid hormones have primarily been extracted from H295R incubation medium by means of liquid-liquid extraction (LLE) and the obtained recoveries and matrix effects have typically not been stated or assessed. In the present study a solid-phase extraction (SPE) method was developed and validated for the simultaneous extraction of cholesterol and five key steroid hormones pregnenolone, 17-hydroxyprogesterone, testosterone, cortisol and aldosterone from H295R incubation medium, and finally detected by LC-MS/MS. Cholesterol was recovered at a level of 55.7%, while steroid hormone recoveries ranged from 98.2 to 109.4%. Matrix effects varied between -0.6% and 62.8%. Intra-day precision was deemed acceptable, but the inter-day precision for pregnenolone and aldosterone exceeded the precision limit of 15% RSD. Although LLE has been the most frequently used extraction method in H295R studies, however, our investigation has shown that SPE may relatively easily extract and recover steroid hormones, potentially replacing LLE.

  • 2.
    Abdel–Khalik, Jonas
    et al.
    Institute of Mass Spectrometry, College of Medicine, Swansea University.
    Björklund, Erland
    Kristianstad University, School of Education and Environment, Avdelningen för Naturvetenskap. Kristianstad University, Plattformen för molekylär analys. Kristianstad University, Faculty of Natural Science, Avdelningen för miljö- och biovetenskap. Kristianstad University, Faculty of Natural Science, Research environment MoLab.
    Hansen, Martin
    Department of Civil & Environmental Engineering, Stanford University.
    Simultaneous determination of endogenous steroid hormones in human and animal plasma and serum by liquid or gas chromatography coupled to tandem mass spectrometry2013In: Journal of chromatography. B, ISSN 1570-0232, E-ISSN 1873-376X, Vol. 928, no June, p. 59-77Article in journal (Refereed)
    Abstract [en]

    Analytical methodologies based on liquid or gas chromatography coupled to tandem mass spectrometry for the simultaneous determination of two or more endogenous steroid hormones in human and animal plasma and serum has received increased attention the last few years. Especially in the clinical setting steroid profiling is of major importance in disease diagnostics. This paper discusses recent findings in such multi-steroid hormone procedures published from 2001 to 2012. The aim was to elucidate possible relationships between chosen analytical technique and the obtained analyte sensitivity for endogenous steroid hormones. By evaluating the success, at which the currently applied techniques have been utilized, more general knowledge on the field is provided. Furthermore the evaluation provides directions in which future studies may be interesting to conduct.

  • 3.
    Abuzooda, Thana
    et al.
    Stockholm University, Faculty of Science, Department of Analytical Chemistry.
    Amini, Ahmad
    Abdel-Rehim, Mohamed
    Stockholm University, Faculty of Science, Department of Analytical Chemistry.
    Graphite-based microextraction by packed sorbent for online extraction of beta-blockers from human plasma samples2015In: Journal of chromatography. B, ISSN 1570-0232, E-ISSN 1873-376X, Vol. 992, p. 86-90Article in journal (Refereed)
    Abstract [en]

    In the present work a new graphitic material (Carbon-XCOS) was used as a sorbent for microextraction by packed sorbent (MEPS).The beta-blockers metoprolol and acebutolol in plasma samples were extracted and detected online using Carbon-MEPS syringe and liquid chromatography and tandem mass spectrometry (LC-MS/MS). Factors affecting the MEPS performance such as conditioning, washing and elution solutions were investigated. The validation of the bioanalytical method was performed using human plasma. The standard curve ranged from 10 to 2000 nM and the lower limit of quantification (LLOQ) was set to 10 nM. The method validation showed good accuracy and precision for the quality control (QC) samples at three concentration levels (30, 800 and 1600 nM). The accuracy values of the QC samples were in the range of 86-108% (n = 18). The precision values of intra- and inter-day for QC samples ranged from 4.4% to 14.4% (RSD) for the both studied analytes. The coefficient of determination (R-2) values were >= 0.999 (n = 3).

  • 4. Abuzooda, Thana
    et al.
    Amini, Ahmad
    Swedish Drug Agency,751 03 Uppsala, Sweden.
    Abdel-Rehim, Mohamed
    Graphite-based microextraction by packed sorbent for online extraction of β-blockers from human plasma samples2015In: Journal of chromatography. B, ISSN 1570-0232, E-ISSN 1873-376X, Vol. 992, p. 86-90Article in journal (Refereed)
    Abstract [en]

    In the present work a new graphitic material (Carbon-XCOS) was used as a sorbent for microextraction by packed sorbent (MEPS). The β-blockers metoprolol and acebutolol in plasma samples were extracted and detected online using Carbon-MEPS syringe and liquid chromatography and tandem mass spectrometry (LC-MS/MS). Factors affecting the MEPS performance such as conditioning, washing and elution solutions were investigated. The validation of the bioanalytical method was performed using human plasma. The standard curve ranged from 10 to 2000nM and the lower limit of quantification (LLOQ) was set to 10nM. The method validation showed good accuracy and precision for the quality control (QC) samples at three concentration levels (30, 800 and 1600nM). The accuracy values of the QC samples were in the range of 86-108% (n=18). The precision values of intra- and inter-day for QC samples ranged from 4.4% to 14.4% (RSD) for the both studied analytes. The coefficient of determination (R(2)) values were ≥0.999 (n=3).

  • 5.
    Ahmadi, Mazaher
    et al.
    Bu Ali Sina Univ, Fac Chem, Hamadan, Iran..
    Moein, Mohammad Mahdi
    Karolinska Inst, Ctr Psychiat Res, Dept Clin Neurosci, SE-17176 Stockholm, Sweden.;Stockholm Cty Council, SE-17176 Stockholm, Sweden..
    Madrakian, Tayyebeh
    Bu Ali Sina Univ, Fac Chem, Hamadan, Iran..
    Afkhami, Abbas
    Bu Ali Sina Univ, Fac Chem, Hamadan, Iran..
    Bahar, Soleiman
    Univ Kurdistan, Fac Sci, Dept Chem, Sanandaj, Iran..
    Abdel-Rehim, Mohamed
    KTH, School of Engineering Sciences (SCI), Applied Physics, Materials and Nanophysics. Karolinska Inst, Ctr Psychiat Res, Dept Clin Neurosci, SE-17176 Stockholm, Sweden.;Stockholm Cty Council, SE-17176 Stockholm, Sweden..
    Reduced graphene oxide as an efficient sorbent in microextraction by packed sorbent: Determination of local anesthetics in human plasma and saliva samples utilizing liquid chromatography-tandem mass spectrometry2018In: Journal of chromatography. B, ISSN 1570-0232, E-ISSN 1873-376X, Vol. 1095, p. 177-182Article in journal (Refereed)
    Abstract [en]

    Herein, reduced graphene oxide (RGO) has been utilized as an efficient sorbent in microextraction by packed sorbent (MEPS). The combination of MEPS and liquid chromatography-tandem mass spectrometry has been used to develop a method for the extraction and determination of three local anesthetics (i.e. lidocaine, prilocaine, and ropivacaine) in human plasma and saliva samples. The results showed that the utilization of RGO in MEPS could minimize the matrix effect so that no interfering peaks at the retention times of the analytes or internal standard was observed. The high extraction efficiency of this method was approved by mean recoveries of 97.26-106.83% and 95.21-105.83% for the studied analytes in plasma and saliva samples, respectively. Intra- and inter-day accuracies and precisions for all analytes were in good accordance with the international regulations. The accuracy values (as percentage deviation from the nominal value) of the quality control samples were between - 2.1 to 13.9 for lidocaine, - 4.2 to 11.0 for prilocaine and between - 4.5 to - 2.4 for ropivacaine in plasma samples while the values were ranged from - 4.6 to 1.6 for lidocaine, from - 4.2 to 15.5 for prilocaine and from - 3.3 to - 2.3 for ropivacaine in human saliva samples. Lower and upper limit of quantification (LLOQ, ULOQ) were set at 5 and 2000 nmol L-1 for all of the studied drugs. The correlation coefficients values were >= 0.995. The limit of detection values were obtained 4 nmol L-1 for lidocaine and prilocaine, and 2 nmol L-1 for ropivacaine.

  • 6.
    Altun, Zeki
    et al.
    Karlstad University, Division for Chemistry.
    Abdel-Rehim, Mohamed
    Karlstad University, Division for Chemistry.
    Blomberg, Lars G.
    Karlstad University, Division for Chemistry.
    New trends in sample preparation: on-line microextraction in packed syringe (MEPS) for LC and GC applications Part III: Determination and validation of local anaesthetics in human plasma samples using a cation-exchange sorbent, and MEPS–LC–MS–MS2004In: Journal of chromatography. B, ISSN 1570-0232, E-ISSN 1873-376X, Vol. 813, no 1-2, p. 129-135Article in journal (Refereed)
  • 7.
    Amelina, Hanna
    et al.
    Stockholm University.
    Sjodin, Marcus O. D.
    Uppsala University.
    Bergquist, Jonas
    Uppsala University.
    Cristobal, Susana
    Linköping University, Department of Clinical and Experimental Medicine. Linköping University, Faculty of Health Sciences.
    Quantitative subproteomic analysis of age-related changes in mouse liver peroxisomes by iTRAQ LC-MS/MS2011In: Journal of chromatography. B, ISSN 1570-0232, E-ISSN 1873-376X, Vol. 879, no 30, p. 3393-3400Article in journal (Refereed)
    Abstract [en]

    Aging is a complex multifactorial phenomenon, which is believed to result from the accumulation of cellular damage to biological macromolecules. Peroxisomes recently emerged as another important source of reactive oxygen species (ROS) production in addition to mitochondria. However, the role of these organelles in the process of aging is still not clear. The aim of this study was to characterize the changes in protein expression profiles of young (10 weeks old) versus old (18 months old) mouse liver peroxisome-enriched fractions. We have applied shotgun proteomic approach based on liquid chromatography and tandem mass spectrometry (LC-MS/MS) combined with iTRAQ (isobaric tags for relative and absolute quantitation) labeling that allows comparative quantitative multiplex analysis. Our analysis led to identification and quantification of 150 proteins, 8 out of which were differentially expressed between two age groups at a statistically significant level (p less than 0.05), with folds ranging from 1.2 to 4.1. These proteins involved in peroxisornal beta-oxidation, detoxification of xenobiotics and production of ROS. Noteworthy, differences in liver proteome have been observed between as well as within different age groups. In conclusion, our subproteomic quantitative study suggests that mouse liver proteome is sufficiently maintained until certain age.

  • 8.
    Amelina, Hanna
    et al.
    Stockholm University, Faculty of Science, Department of Biochemistry and Biophysics.
    Sjodin, Marcus O. D.
    Bergquist, Jonas
    Cristobal, Susana
    Stockholm University, Faculty of Science, Department of Biochemistry and Biophysics.
    Quantitative subproteomic analysis of age-related changes in mouse liver peroxisomes by iTRAQ LC-MS/MS2011In: Journal of chromatography. B, ISSN 1570-0232, E-ISSN 1873-376X, Vol. 879, no 30, p. 3393-3400Article in journal (Refereed)
    Abstract [en]

    Aging is a complex multifactorial phenomenon, which is believed to result from the accumulation of cellular damage to biological macromolecules. Peroxisomes recently emerged as another important source of reactive oxygen species (ROS) production in addition to mitochondria. However, the role of these organelles in the process of aging is still not clear. The aim of this study was to characterize the changes in protein expression profiles of young (10 weeks old) versus old (18 months old) mouse liver peroxisome-enriched fractions. We have applied shotgun proteomic approach based on liquid chromatography and tandem mass spectrometry (LC-MS/MS) combined with iTRAQ (isobaric tags for relative and absolute quantitation) labeling that allows comparative quantitative multiplex analysis. Our analysis led to identification and quantification of 150 proteins, 8 out of which were differentially expressed between two age groups at a statistically significant level (p < 0.05), with folds ranging from 1.2 to 4.1. These proteins involved in peroxisornal beta-oxidation, detoxification of xenobiotics and production of ROS. Noteworthy, differences in liver proteome have been observed between as well as within different age groups. In conclusion, our subproteomic quantitative study suggests that mouse liver proteome is sufficiently maintained until certain age.

  • 9.
    Amelina, Hanna
    et al.
    Stockholm University, Faculty of Science, Department of Biochemistry and Biophysics.
    Sjödin, Marcus O. D.
    Bergquist, Jonas
    Cristobal, Susana
    Stockholm University, Faculty of Science, Department of Biochemistry and Biophysics.
    Quantitative subproteomic analysis of age-related changes in mouse liver peroxisomes by iTRAQ LC-MS/MSIn: Journal of chromatography. B, ISSN 1570-0232, E-ISSN 1873-376XArticle in journal (Refereed)
  • 10. Amelina, Hanna
    et al.
    Sjödin, Marcus O.D.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical and Analytical Chemistry.
    Bergquist, Jonas
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical and Analytical Chemistry.
    Cristobal, Susana
    Quantitative subproteomic analysis of age-related changes in mouse liver peroxisomes by iTRAQ LC-MS/MS2011In: Journal of chromatography. B, ISSN 1570-0232, E-ISSN 1873-376X, Vol. 879, no 30, p. 3393-3400Article in journal (Refereed)
    Abstract [en]

    Aging is a complex multifactorial phenomenon, which is believed to result from the accumulation of cellular damage to biological macromolecules. Peroxisomes recently emerged as another important source of reactive oxygen species (ROS) production in addition to mitochondria. However, the role of these organelles in the process of aging is still not clear. The aim of this study was to characterize the changes in protein expression profiles of young (10 weeks old) versus old (18 months old) mouse liver peroxisome-enriched fractions. We have applied shotgun proteomic approach based on liquid chromatography and tandem mass spectrometry (LC-MS/MS) combined with iTRAQ (isobaric tags for relative and absolute quantitation) labeling that allows comparative quantitative multiplex analysis. Our analysis led to identification and quantification of 150 proteins, 8 out of which were differentially expressed between two age groups at a statistically significant level (p < 0.05), with folds ranging from 1.2 to 4.1. These proteins involved in peroxisornal beta-oxidation, detoxification of xenobiotics and production of ROS. Noteworthy, differences in liver proteome have been observed between as well as within different age groups. In conclusion, our subproteomic quantitative study suggests that mouse liver proteome is sufficiently maintained until certain age.

  • 11.
    Amini, Nahid
    et al.
    Stockholm University, Faculty of Science, Department of Analytical Chemistry.
    Crescenzi, Carlo
    Feasibility of an on-line restricted access material/liquidchromatography/tandem mass spectrometry method in the rapid and sensitive determination of organophosphorustriesters in human blood plasma2003In: Journal of chromatography. B, ISSN 1570-0232, E-ISSN 1873-376X, Vol. 795, no 2, p. 245-256Article in journal (Refereed)
    Abstract [en]

    A rapid on-line solid phase extraction/liquid chromatography/tandem mass spectrometry (SPE/LC/MS/MS) method usingrestricted access material (RAM) was developed for the simultaneous determination of eight organophosphorus triesters inuntreated human blood plasma. In a process involving column-switching techniques, the analytes were enriched on the RAMcolumn, separated using a C-18 analytical column and detected with LC/MS. Tandem mass spectrometrywas used to characterizeand quantify the analytes. To elucidate the fragmentation pathway of a number of the analytes, MS3 experiments using an iontrap mass spectrometer were performed. The matrix effects associated with using APCI and ESI interfaces were investigated.The recoveries obtained were in the range 60–92% (R.S.D. < 6%), with estimated detection limits between 0.2 and 1.8 ng/mlof plasma, and the total analysis time was 27 min.

  • 12. Anderot, Maria
    et al.
    Nilsson, Mikael
    Vegvari, Akos
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Biochemistry and Organic Chemistry.
    Moeller, Horn
    van de Weert, Marco
    Isaksson, Roland
    Determination of dissociation constants between polyelectrolytes and proteins by affinity capillary electrophoresis2009In: Journal of chromatography. B, ISSN 1570-0232, E-ISSN 1873-376X, Vol. 877, no 10, p. 892-896Article in journal (Refereed)
    Abstract [en]

    In this manuscript we report the binding affinity between two model proteins, human serum albumin (HSA) and ribonuclease A (RNase A), and negatively charged polyelectrolytes, two different heparin fractions and dextran sulfate, by means of partial filling and affinity capillary electrophoresis. The apparent dissociation constants, K-d, obtained by use of the partial-filling method, between HSA and heparin (17 kDa), heparin (3 kDa) and dextran sulfate (8 kDa) were 33 and 307 mu M, respectively. A new method was developed to determine affinities that take in account different migration directions between the protein and the polyelectrolyte, which was required to study RNase A. By use of this affinity capillary electrophoresis two K-d values were observed for the interaction between RNase A and heparin 17 kDa, yielding a high affinity binding with K-d1 0.0075 mu M, and a lower affinity binding with K-d2 8.7 mu M. For dextran sulfate 8 kDa these K-d values were 0.027 and 10.4 mu M, respectively. Heparin 3 kDa only showed a single K-d value of 0.52 mu M. The results show that the magnitude of the binding affinity depends on the type of polyelectrolyte and its molecular weight. (C) 2009 Elsevier B.V. All rights reserved.

  • 13.
    Arvidsson, Björn
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical and Analytical Chemistry.
    Allard, Erik
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical and Analytical Chemistry.
    Sjögren, Erik
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Pharmacy.
    Lennernäs, Hans
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Pharmacy.
    Sjöberg, Per Johan Ragnar
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical and Analytical Chemistry.
    Bergquist, Jonas
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical and Analytical Chemistry.
    Online capillary solid phase extraction and liquid chromatographic separation with quantitative tandem mass spectrometric detection (SPE-LC-MS/MS) of ximelagatran and its metabolites in a complex matrix.2009In: Journal of chromatography. B, ISSN 1570-0232, E-ISSN 1873-376X, Vol. 877, no 3, p. 291-297Article in journal (Refereed)
    Abstract [en]

    This work presents the development and validation of a fully automated quantitative analysis method of melagatran, its prodrug ximelagatran, and its major metabolites for the study of drug behavior in biofluids. The method involves online sample clean-up and enrichment on a C4 capillary column followed by separation on a capillary C18 column. Electrospray ionization tandem mass spectrometric detection in positive ion mode was performed with multiple reactions monitoring of eight different transients, divided into two time segments with four transients each. The structural similarity, the complexity of the matrix (pig liver extract) and the formation of isobaric fragment ions, made efficient chromatographic separation necessary. The analysis method provides valid accuracy (<9%; RSD%), precision (<8%; RSD%), linearity (<1.2 nM–1 μM; R2 > 0.999), limit of quantitation (<3.6 nM), retention repeatability (<1.2%; RSD%), selectivity, as well as analyte and column stabilities over a wide concentration range.

  • 14.
    Baranowska, Irena
    et al.
    Silesian Technical University, Poland .
    Magiera, Sylwia
    Silesian Technical University, Poland .
    Baranowski, Jacek
    Linköping University, Department of Medical and Health Sciences, Clinical Physiology. Linköping University, Faculty of Health Sciences.
    Clinical applications of fast liquid chromatography: A review on the analysis of cardiovascular drugs and their metabolites2013In: Journal of chromatography. B, ISSN 1570-0232, E-ISSN 1873-376X, Vol. 927, no SI, p. 54-79Article, review/survey (Refereed)
    Abstract [en]

    One of the major challenges facing the medicine today is developing new therapies that enhance human health. To help address these challenges the utilization of analytical technologies and high-throughput automated platforms has been employed; in order to perform more experiments in a shorter time frame with increased data quality. In the last decade various analytical strategies have been established to enhance separation speed and efficiency in liquid chromatography applications. Liquid chromatography is an increasingly important tool for monitoring drugs and their metabolites. Furthermore, liquid chromatography has played an important role in pharmacokinetics and metabolism studies at these drug development stages since its introduction. This paper provides an overview of current trends in fast chromatography for the analysis of cardiovascular drugs and their metabolites in clinical applications. Current trends in fast liquid chromatographic separations involve monolith technologies, fused-core columns, high-temperature liquid chromatography (HTLC) and ultra-high performance liquid chromatography (UHPLC). The high specificity in combination with high sensitivity makes it an attractive complementary method to traditional methodology used for routine applications. The practical aspects of, recent developments in and the present status of fast chromatography for the analysis of biological fluids for therapeutic drug and metabolite monitoring, pharmacokinetic studies and bioequivalence studies are presented.

  • 15. Bennemo, Mia
    et al.
    Blom, Hans
    Emilsson, Anna
    Lemmens, Raf
    A chromatographic method for determination of supercoiled plasmid DNA concentration in complex solutions.2009In: Journal of chromatography. B, ISSN 1570-0232, E-ISSN 1873-376X, Vol. 877, no 24, p. 2530-6Article in journal (Refereed)
    Abstract [en]

    A method for determination of the plasmid DNA concentration with subsequent analysis of the ratio supercoiled to open circular form is presented. The method is suitable for samples from all steps of the manufacturing process, from fermentation to final product. The analysis consists of size exclusion chromatography, followed by analytical thiophilic aromatic chromatography. In the first step, the plasmid DNA concentration is determined by group separation, including removal of RNA and other impurities, within less than 2 min. The limit of detection and quantification was 0.28 and 0.83 microg/ml, respectively. The precision of the method is high, providing a coefficient of variation as low as below 2%. In the second step, the ratio of open circular to supercoiled plasmid DNA is determined following separation of the two plasmid DNA isoforms with a linear salt gradient. The precision of the second step was evaluated using serial injections of aliquots of a sample stock solution. In comparison with the two most commonly used methods, the developed analysis was found to be significantly more accurate than agarose gel electrophoresis and equivalent to capillary gel electrophoresis. The combined methods for quantification and control of homogeneity of plasmid DNA presented here enable reliable and precise analysis at all steps of the manufacturing process.

  • 16.
    Bergstrom, Maria
    et al.
    Linnaeus University.
    Åström, Eva
    Linköping University, Department of Clinical and Experimental Medicine, Cell Biology. Linköping University, Faculty of Health Sciences.
    Påhlsson, Peter
    Linköping University, Department of Clinical and Experimental Medicine, Cell Biology. Linköping University, Faculty of Health Sciences.
    Ohlson, Sten
    Linnaeus University.
    Elucidating the selectivity of recombinant forms of Aleuria aurantia lectin using weak affinity chromatography2012In: Journal of chromatography. B, ISSN 1570-0232, E-ISSN 1873-376X, Vol. 885, p. 66-72Article in journal (Refereed)
    Abstract [en]

    Aberrant glycosylation is connected to several pathological conditions and lectins are useful tools to characterize glycosylated biomarkers. The Aleuria aurantia lectin (AAL) is of special interest since it interacts with all types of fucosylated saccharides. AAL has been expressed in Escherichia coil as a fully functional recombinant protein. Engineered variants of AAL have been developed with the aim of creating monovalent lectins with more homogenous binding characteristics. Four different forms of AAL were studied in the present work: native AAL purified from A. aurantia mushrooms, recombinant AAL dimer, recombinant AAL monomer and recombinant AAL site 2 (S2-AAL). The affinities of these AAL forms toward a number of saccharides were determined with weak affinity chromatography (WAC). Disaccharides with fucose linked alpha 1-3 to GIcNAc interacted with higher affinity compared to fucose linked alpha 1-6 or alpha 1-4 and the obtained dissociation constants (K-d) were in the range of 10 mu M for all AAL forms. Tetra- and pentasaccharides with fucose in alpha 1-2, alpha 1-3 or alpha 1-4 had K-d values ranging from 0.1 to 7 mM while a large alpha 1-6 fucosylated oligosaccharide had a K-d of about 20 mu M. The recombinant multivalent AAL forms and native AAL exhibited similar affinities toward all saccharides, but S2-AAL had a lower affinity especially regarding a sialic acid containing fucosylated saccharide. It was demonstrated that WAC is a valuable technique in determining the detailed binding profile of the lectins. Specific advantages with WAC include a low consumption of non-labeled saccharides, possibility to analyze mixtures and a simple procedure using standard HPLC equipment.

  • 17. Bergström, Maria
    et al.
    Nilsson, Mikael
    Isaksson, Roland
    Rydén, Ingvar
    Påhlsson, Peter
    Linköping University, Faculty of Health Sciences. Linköping University, Department of Biomedicine and Surgery, Division of cell biology.
    Ohlson, Sten
    Lectin affinity capillary electrophoresis in glycoform analysis applying the partial filling technique2004In: Journal of chromatography. B, ISSN 1570-0232, E-ISSN 1873-376X, Vol. 809, no 2, p. 323-329Article in journal (Refereed)
    Abstract [en]

    The study of protein glycosylation and its significance in biological interactions is a field of growing interest. This work demonstrates a lectin-based separation of protein glycoforms of α1-acid glycoprotein (AGP or orosomucoid) with capillary electrophoresis. Glycoform analysis was performed with a "partial filling technique" with the lectin Concanavalin A (Con A) as affinity ligand. Con A separated human AGP into two peaks, the first peak included AGP glycoforms without biantennary glycans, and the second peak represented the fraction that had one or more biantennary glycans. The applicability of the method was demonstrated with the analysis of AGP from clinical samples and AGP treated with N-glycosidase F. The AGP separation was also used as a reporter system to estimate the dissociation constant (KD) between Con A and a competing sugar. © 2004 Elsevier B.V. All rights reserved.

  • 18.
    Bergström, Maria
    et al.
    Linnaeus University, Faculty of Science and Engineering, School of Natural Sciences.
    Åström, Eva
    Påhlsson, Peter
    Ohlson, Sten
    Linnaeus University, Faculty of Science and Engineering, School of Natural Sciences.
    Elucidating the selectivity of recombinant forms of Aleuria aurantia lectin using weak affinity chromatography2012In: Journal of chromatography. B, ISSN 1570-0232, E-ISSN 1873-376X, Vol. 885-886, p. 66-72Article in journal (Refereed)
    Abstract [en]

    Aberrant glycosylation is connected to several pathological conditions and lectins are useful tools to characterize glycosylated biomarkers. The Aleuria aurantia lectin (AAL) is of special interest since it interacts with all types of fucosylated saccharides. AAL has been expressed in E.coli as a fully functional recombinant protein. Engineered variants of AAL have been developed with the aim of creating monovalent lectins with more homogenous binding characteristics. Four different forms of AAL were studied in the present work: native AAL purified from Aleuria aurantia mushrooms, recombinant AAL dimer, recombinant AAL monomer and recombinant AAL site 2 (S2-AAL). The affinities of these AAL forms towards a number of saccharides were determined with weak affinity chromatography (WAC). Disaccharides with fucose linked α1-3 to GlcNAc interacted with higher affinity compared to fucose linked α1-6 or α1-4 and the obtained dissociation constants (Kd) were in the range of 10 μM for all AAL forms. Tetra- and pentasaccharides with fucose in α1-2, α1-3 or α1-4 had Kd values ranging from 0.1–7 mM while a large α1-6 fucosylated oligosaccharide had a Kd of about 20 μM. The recombinant multivalent AAL forms and native AAL exhibited similar affinities towards all saccharides, but S2-AAL had a lower affinity especially regarding a sialic acid containing fucosylated saccharide. It was demonstrated that WAC is a valuable technique in determining the detailed binding profile of the lectins. Specific advantages with WAC include a low consumption of non-labeled saccharides, possibility to analyze mixtures and a simple procedure using standard HPLC equipment.

  • 19.
    Bergström, Sara K.
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry, Analytical Chemistry.
    Markides, Karin E.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry, Analytical Chemistry.
    On-line coupling of microdialysis to packed capillary column liquid chromatography-tandem mass spectrometry demonstrated by measurement of free concentrations of ropivacaine and metabolite from spiked plasma samples2002In: Journal of chromatography. B, ISSN 1570-0232, E-ISSN 1873-376X, Vol. 775, no 1, p. 79-87Article in journal (Refereed)
    Abstract [en]

    An on-line coupling of microdialysis to a packed capillary column switching liquid chromatographic system (0.2 mm I.D.) and mass spectrometric detection was developed. The microdialysates were collected in the loop of the first of three valves, coupled in direct series. A deuterated internal standard was added on-line by the middle valve and the third valve operated both a pre-column, for desalting of the physiological buffer used in the sampling procedure, and a separation column. The on-line system was used to study free concentrations of ropivacaine and its metabolite (PPX) in human plasma samples. The analytes were detected by electrospray ionization in a tandem mass spectrometer operating in multiple reaction monitoring mode. The free fractions of ropivacaine (200 nM total concentration) and PPX (20 nM total concentration) in spiked plasma samples were 12±3 and 47±5% (±standard deviation for day-to-day variations, n=3), respectively.

  • 20.
    Boström, Tove
    et al.
    KTH, School of Biotechnology (BIO), Protein Technology.
    Ottosson Takanen, Jenny
    KTH, School of Biotechnology (BIO), Proteomics and Nanobiotechnology.
    Hober, Sophia
    KTH, School of Biotechnology (BIO), Protein Technology.
    Antibodies as means for selective mass spectrometry2015In: Journal of chromatography. B, ISSN 1570-0232, E-ISSN 1873-376XArticle in journal (Refereed)
    Abstract [en]

    For protein analysis of biological samples, two major strategies are used today; mass spectrometry (MS) and antibody-based methods. Each strategy offers advantages and drawbacks. However, combining the two using an immunoenrichment step with MS analysis brings together the benefits of each method resulting in increased sensitivity, faster analysis and possibility of higher degrees of multiplexing. The immunoenrichment can be performed either on protein or peptide level and quantification standards can be added in order to enable determination of the absolute protein concentration in the sample. The combination of immunoenrichment and MS holds great promise for the future in both proteomics and clinical diagnostics. This review describes different setups of immunoenrichment coupled to mass spectrometry and how these can be utilized in various applications.

  • 21.
    Casas, Monica Escolà
    et al.
    Danmark.
    Hansen, Martin
    Danmark.
    Krogh, Kristine A.
    Danmark.
    Styrishave, Bjarne
    Danmark.
    Björklund, Erland
    Kristianstad University, School of Education and Environment, Avdelningen för Naturvetenskap. Kristianstad University, Plattformen för molekylär analys. Kristianstad University, Faculty of Natural Science, Avdelningen för miljö- och biovetenskap. Kristianstad University, Faculty of Natural Science, Research environment MoLab.
    Analytical sample preparation strategies for the determination of antimalarial drugs in human whole blood, plasma and urine2014In: Journal of chromatography. B, ISSN 1570-0232, E-ISSN 1873-376X, Vol. 962, p. 109-131Article in journal (Refereed)
    Abstract [en]

    Antimalarial drugs commonly referred to as antimalarials, include a variety of compounds with different physicochemical properties. There is a lack of information on antimalarial distribution in the body over time after administration, e.g. the drug concentrations in whole blood, plasma, and urine, which must be improved in order to advance curing the parasitic disease malaria. A key problem also lies in that pharmacokinetic studies not always are performed in patient groups that may benefit most of the treatment such as children, pregnancy and lower-weight ethnic populations. Here we review the available sample preparation strategies combined with liquid chromatographic (LC) analysis to determine antimalarials in whole blood, plasma and urine published over the last decade. Sample preparation can be done by protein precipitation, solid-phase extraction, liquid-liquid extraction or dilution. After LC separation, the preferred detection tool is tandem mass spectrometry (MS/MS) but other detection methods have been used e.g. UV, fluorescence and electrochemical detection. Major trends for sample preparation of the different groups of antimalarials for each matrix and its detection have been summarized. Finally, the main problems that the researchers have dealt with are highlighted. This information will aid analytical chemists in the development of novel methods for determining existing antimalarials and upcoming new drugs

  • 22. Chadt, J
    et al.
    Sykora, D
    Nilsson, Robert
    Stockholm University, Faculty of Science, Department of Genetics, Microbiology and Toxicology.
    Monitoring of dimethyl sulphate-induced N3-methyladenine, N7-methylguanine and O6-methylguanine DNA adducts using reversed-phase high performance liquid chromatography and mass spectrometry 2008In: Journal of chromatography. B, ISSN 1570-0232, E-ISSN 1873-376X, Vol. 867, p. 43-48Article in journal (Refereed)
    Abstract [en]

    This work describes the determination of N3-methyladenine, N7-methylguanine and O6-methylguanine adducts in dimethyl sulphate-treated salmon-testes DNA employing reversed-phase high performance liquid chromatography (RP-HPLC) with UV–vis detection, followed by mass-spectrometric verification using electrospray ionisation in positive mode ESI(+). Within validation parameters, accuracy, precision, calibration parameters, limit of detection (LOD) and quantitation (LOQ) as well as stability of standard stock solutions were tested and presented for UV/vis detection. The limit of detection (LOD) was found to be 0.1 ng/mL for N3-methyladenine and 0.2 ng/mL for both N7-methylguanine and O6-methylguanine (S/N = 3). The limit of quantitation (LOQ) was found to be 0.5 ng/mL for all measured compounds, (S/N = 10). Quantitative results were obtained for each substance based on eight-point calibration. Intra- and inter-day precisions were within 1.73–6.96 and 2.26–7.58%, respectively, and correlation coefficients of calibration curves (R2) ranged from 0.9992 to 0.9997. Relative proportion of N7-methylguanine was accounted for 61.53 ± 2.97% (R.S.D. = 4.8), N3-methyladenine for 38.19 ± 2.99% (R.S.D. = 9.6) and O6-methylguanine for 0.29 ± 0.02% (R.S.D. = 5.1), respectively. The application of the above-mentioned techniques provides a valuable contribution for simultaneous determination of methylated DNA adducts, and may represent a suitable approach for similar monitoring/screening studies.

  • 23.
    Claeson, Anna-Sara
    et al.
    Umeå University, Faculty of Social Sciences, Department of Psychology.
    Gouveia-Figueira, Sandra C.
    Swedish Metabolomics Centre (SMC), Umeå, Sweden.
    Stenlund, Hans
    Swedish Metabolomics Centre (SMC), Umeå, Sweden.
    Johansson, Annika I.
    Swedish Metabolomics Centre (SMC), Umeå, Sweden.
    A standardized protocol for comparable analysis of GSH/GSSG by UHPLC-ESI-MSMS for human plasma2019In: Journal of chromatography. B, ISSN 1570-0232, E-ISSN 1873-376X, Vol. 1104, p. 67-72Article in journal (Refereed)
    Abstract [en]

    Variability in the levels of GSH and GSSG in plasma is suggested to derive from inadequate pre-processing methods. The aim of this study was to develop a protocol for comparable and reliable measurements of GSH/GSSG. Venous blood from 8 healthy individuals were collected and divided into 7 different pre-processing procedures. For three of the samples an extraction mixture was added after 0 (baseline), 4 and 8 min and for three of the samples the extraction mixture was added at different times during defrost. A worst case scenario where a sample was left in a cool box during 6 h was also included. The samples were analyzed with UHPLC-ESIMSMS. A large difference in the levels of GSH and GSSG were identified and it was clearly associated with the sample handling procedures. A sample left untreated for 4 min will have significantly reduced amount of GSH. Stability tests showed that the level of GSH was reduced after 3 months in -80 degrees C.

  • 24.
    Claeson Bohnstedt, Kristina
    et al.
    Stockholm University, Faculty of Science, Department of Analytical Chemistry.
    Karlberg, Bo
    Stockholm University, Faculty of Science, Department of Analytical Chemistry.
    Basun, Hans
    Schmidt, Staffan
    Porous graphitic carbon chromatography-tandem mass spectrometry for the detection of isoprostanes in human cerebrospinal fluid2005In: Journal of chromatography. B, ISSN 1570-0232, E-ISSN 1873-376X, Vol. 827, no 1, p. 39-43Article in journal (Refereed)
    Abstract [en]

    F2-isoprostanes are produced by the non-enzymatic peroxidation of arachidonic acid in membrane phospholipids. This paper describes a new method for the determination of all four classes of F2-isoprostanes in human cerebrospinal fluid (CSF) involving separation on a 1 mm × 150 mm porous graphitic carbon (PGC) column and detection by triple quadrupole mass spectrometry in negative-ion electrospray mode. The sample pre-treatment consisted of an ultrafiltration step, following which 300 μl of CSF sample could be injected directly onto a 1 mm × 10 mm PGC guard column functioning as a trap for the analytes. The loading solvent was Milli-Q water at 125 μl/min. After 3 min, the sample was switched into the separation column. The F2-isoprostanes were separated in 20 min using a linear solvent gradient comprising water, methanol, acetonitrile and ammonium hydroxide at a pH of 9.5 and a flow of 50 μl/min The limit of detection (calculated as 3S/N) was approximately 40 pM (14 pg/ml). The assay was linear within the examined range (18–450 pg/ml), using CSF spiked with iPF2α-III standard (r2 > 0.995). Repeatability data were calculated for CSF spiked to 90 pg/ml and the relative standard deviation (RSD) obtained was 3% (n = 6).

  • 25.
    Dalpiaz, Alessandro
    et al.
    University of Ferrara.
    Marchetti, Nicola
    University of Ferrara.
    Cavazzini, Alberto
    University of Ferrara.
    Pasti, Luisa
    University of Ferrara.
    Velaga, Sitaram
    Luleå University of Technology, Department of Health Sciences, Medical Science.
    Gavini, Elisabetta
    University of Sassari.
    Beggiato, Ssrah
    University of Ferrara.
    Ferraro, Luca
    University of Ferrara, Department of Clinical and Experimental Medicine, Pharmacol Sect.
    Quantitative determination of zolmitriptan in rat blood and cerebrospinal fluid by reversed phase HPLC-ESI-MS/MS analysis: application to in vivo preclinical pharmacokinetic study2012In: Journal of chromatography. B, ISSN 1570-0232, E-ISSN 1873-376X, Vol. 901, p. 72-78Article in journal (Refereed)
    Abstract [en]

    A fast HPLC-ESI-MS/MS method has been developed and validated for the quantification of the potent and selective antimigraine zolmitriptan in rat blood and cerebrospinal fluid (CSF). The assay has been then applied for in vivo preclinical studies. The analytical determination has been used to obtain pharmacokinetics of zolmitriptan in the two biological matrices after its intravenous or nasal administration. Liquid-liquid extraction of zolmitriptan was performed from 100μL rat blood samples in the presence of N 6-cyclopentyladenosine (internal standard) with the employment of ethyl acetate. Calibration standards were prepared by using blood matrix and following the same liquid-liquid extraction procedure. CSF samples were analyzed without any pre-treatment steps and by using an external calibration method in pure water matrix. Chromatographic separation was performed under reversed phase and a gradient elution condition on a C18 packed column (100×2.0mm, 2.5μm particles diameter). The mobile phase was a mixture between acetonitrile, water and formic acid (0.1% v/v). The applied HPLC-MS/MS method allowed low limits of detection, as calculated from calibration curves, of 6.6 and 24.4ng/mL for water matrix and rat blood extracts, respectively. Linearity of the calibration curves was established up to 5μM (1.44μg/mL), as well as good assay accuracy. The intravenous infusion of 20μg zolmitriptan to male Sprague-Dawley rats produced blood concentrations ranging from 9.4±0.7 to 1.24±0.07μg/mL within 10h, with a terminal half-life of 3.4±0.2h. The nasal administration of a water suspension of 20μg zolmitriptan produced blood concentrations ranging from 2.92±0.21 to 0.85±0.07μg/mL within 6h. One hour after zolmitriptan intravenous infusion or nasal administration, its CSF concentrations were 0.0539±0.0016 and 0.0453±0.0012μg/mL, respectively. This study determined the suitability of the herein proposed method to investigate the pharmacokinetics of zolmitriptan after its administration by means of novel formulations and, hence, to evaluate the efficacy of innovative nose-to-brain drug delivery in preclinical studies.

  • 26. Davids, Mariska
    et al.
    Swieringa, Eliane
    Palm, Fredrik
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical Cell Biology, Integrative Physiology.
    Smith, Desiree E. C.
    Smulders, Yvo M.
    Scheffer, Peter G.
    Blom, Henk J.
    Teerlink, Tom
    Simultaneous determination of asymmetric and symmetric dimethylarginine, L-monomethylarginine, L-arginine, and L-homoarginine in biological samples using stable isotope dilution liquid chromatography tandem mass spectrometry2012In: Journal of chromatography. B, ISSN 1570-0232, E-ISSN 1873-376X, Vol. 900, p. 38-47Article in journal (Refereed)
    Abstract [en]

    Production of the endogenous vasodilator nitric oxide (NO) from L-arginine by NO synthase is modulated by L-homoarginine, L-monomethylargine (MMA), asymmetric dimethylarginine (ADMA) and symmetric dimethylarginine (SDMA). Here we report on a stable isotope dilution liquid chromatography tandem mass spectrometry (LC-MS/MS) method for simultaneous determination of these metabolites in plasma, cells and tissues. After addition of the internal standards (D-7-ADMA, D-4-L-homoarginine and C-13(6)-Larginine), analytes were extracted from the samples using Waters Oasis MCX solid phase extraction cartridges. Butylated analytes were separated isocratically on a Waters XTerra MS C18 column (3.5 mu m. 3.9 mm x 100 mm) using 600 mg/L ammonium formate in water - acetonitrile (95.5:4.5, v/v) containing 0.1 vol% formic acid, and subsequently measured on an AB Sciex API 3000 triple quadrupole mass spectrometer. Multiple reaction monitoring in positive mode was used for analyte quantification. Validation was performed in plasma. Calibration lines were linear (r(2) >= 0.9979) and lower limits of quantification in plasma were 0.4 nM for ADMA and SDMA and 0.8 nM for the other analytes. Accuracy (% bias) was <3% except for MMA (<7%), intra-assay precision (expressed as CV) was <3.5%, inter-assay precision <9.6%, and recovery 92.9-103.2% for all analytes. The method showed good correlation (r(2) >= 0.9125) with our previously validated HPLC-fluorescence method for measurement in plasma, and was implemented with good performance for measurement of tissue samples. Application of the method revealed the remarkably fast (i.e. within 60 min) appearance in plasma of stable isotope-labeled ADMA, SDMA, and MMA during infusion of D-3-methyl-1-C-13-methionine in healthy volunteers.

  • 27.
    Davids, Mariska
    et al.
    Metabolic Laboratory, Department of Clinical Chemistry, VU University Medical Center, Amsterdam, The Netherlands, Institute for Cardiovascular Research (ICaR-VU), Amsterdam, The Netherlands, .
    Swieringa, Eliane
    Metabolic Laboratory, Department of Clinical Chemistry, VU University Medical Center, Amsterdam, The Netherlands.
    Palm, Fredrik
    Linköping University, Department of Medical and Health Sciences, Division of Drug Research. Linköping University, Faculty of Health Sciences.
    Smith, Desirée E C
    Metabolic Laboratory, Department of Clinical Chemistry, VU University Medical Center, Amsterdam, The Netherlands.
    Smulders, Yvo M
    Institute for Cardiovascular Research (ICaR-VU), Amsterdam, The Netherlands, Department of Internal Medicine, VU University Medical Center, Amsterdam, The Netherlands.
    Scheffer, Peter G
    Metabolic Laboratory, Department of Clinical Chemistry, VU University Medical Center, Amsterdam, The Netherlands, Institute for Cardiovascular Research (ICaR-VU), Amsterdam, The Netherlands.
    Blom, Henk J
    Metabolic Laboratory, Department of Clinical Chemistry, VU University Medical Center, Amsterdam, The Netherlands, Institute for Cardiovascular Research (ICaR-VU), Amsterdam, The Netherlands.
    Teerlink, Tom
    Metabolic Laboratory, Department of Clinical Chemistry, VU University Medical Center, Amsterdam, The Netherlands, Institute for Cardiovascular Research (ICaR-VU), Amsterdam, The Netherlands.
    Simultaneous determination of asymmetric and symmetric dimethylarginine, l-monomethylarginine, l-arginine, and l-homoarginine in biological samples using stable isotope dilution liquid chromatography tandem mass spectrometry2012In: Journal of chromatography. B, ISSN 1570-0232, E-ISSN 1873-376X, Vol. 900, p. 38-47Article in journal (Refereed)
    Abstract [en]

    Production of the endogenous vasodilator nitric oxide (NO) from l-arginine by NO synthase is modulated by l-homoarginine, l-monomethylargine (MMA), asymmetric dimethylarginine (ADMA) and symmetric dimethylarginine (SDMA). Here we report on a stable isotope dilution liquid chromatography tandem mass spectrometry (LC-MS/MS) method for simultaneous determination of these metabolites in plasma, cells and tissues. After addition of the internal standards (D(7)-ADMA, D(4)-l-homoarginine and (13)C(6)-l-arginine), analytes were extracted from the samples using Waters Oasis MCX solid phase extraction cartridges. Butylated analytes were separated isocratically on a Waters XTerra MS C18 column (3.5μm, 3.9mm×100mm) using 600mg/L ammonium formate in water - acetonitrile (95.5:4.5, v/v) containing 0.1vol% formic acid, and subsequently measured on an AB Sciex API 3000 triple quadrupole mass spectrometer. Multiple reaction monitoring in positive mode was used for analyte quantification. Validation was performed in plasma. Calibration lines were linear (r(2)≥0.9979) and lower limits of quantification in plasma were 0.4nM for ADMA and SDMA and 0.8nM for the other analytes. Accuracy (% bias) was <3% except for MMA (<7%), intra-assay precision (expressed as CV) was <3.5%, inter-assay precision <9.6%, and recovery 92.9-103.2% for all analytes. The method showed good correlation (r(2)≥0.9125) with our previously validated HPLC-fluorescence method for measurement in plasma, and was implemented with good performance for measurement of tissue samples. Application of the method revealed the remarkably fast (i.e. within 60min) appearance in plasma of stable isotope-labeled ADMA, SDMA, and MMA during infusion of D(3)-methyl-1-(13)C-methionine in healthy volunteers.

  • 28. Delgado, C
    et al.
    Malmsten, M
    YKI – Ytkemiska institutet.
    Van Alstine, JM
    Analytical partitioning of poly(ethyleneglycol)-modified proteins1997In: Journal of chromatography. B, ISSN 1570-0232, E-ISSN 1873-376X, Vol. 692, p. 263-272Article in journal (Refereed)
    Abstract [en]

    Covalently grafting proteins with varying numbers (n) of poly(ethylene glycol) molecules (PEGs) often enhances their biomedical and industrial usefulness. Partition between the phases in aqueous polymer two-phase systems can be used to rapidly characterize polymer-protein conjugates in a manner related to various enhancements. The logarithm of the partition coefficient (K) approximates linearity over the range 0

  • 29.
    El Beqqali, Aziza
    et al.
    Stockholm University, Faculty of Science, Department of Environmental Science and Analytical Chemistry.
    Ahmadi, Mazaher
    Stockholm University, Faculty of Science, Department of Environmental Science and Analytical Chemistry.
    Abdel-Rehim, Mohamed
    Stockholm University, Faculty of Science, Department of Environmental Science and Analytical Chemistry.
    Determination of AZD6118 in dog plasma samples utilizing microextraction by packed sorbent and liquid chromatography-electrospray ionization tandem mass spectrometry2017In: Journal of chromatography. B, ISSN 1570-0232, E-ISSN 1873-376X, Vol. 1043, p. 20-24Article in journal (Refereed)
    Abstract [en]

    In this work, for the first time, a method has been developed for the determination of AZD6118, a candidate drug, in dog plasma samples. The method is based on microextraction by packed sorbent (MEPS) of the drug prior to liquid chromatography-electrospray ionization tandem mass spectrometry assay. Various important factors affecting MEPS performance were optimized, and under the optimized condition, a linear calibration curve in the concentration range of 20-25,000 nmol L-1 with a coefficient of determination over 0.99 was obtained. The back-calculated values of the calibration points showed good agreement with the theoretical concentrations (coefficients of variation percent between 0.3-3.8). The lower limit of quantification and limit of detection were 20.0 and 2.9 nmol L-1, respectively. The repeatability and accuracy of the method was evaluated by determination of quality control samples at three concentration levels (low, medium and high) using the developed method, and the results (coefficients of variation values were between 1.9% and 3.2%, relative recoveries ranged between 93.5-102.1%) confirm that a powerful method has been developed for the extraction and determination of the investigated drug in dog plasma.

  • 30.
    El-Beqqali, Aziza
    et al.
    Stockholm University, Faculty of Science, Department of Environmental Science and Analytical Chemistry.
    Andersson, Lars I.
    Jeppsson, Amin Dadoun
    Abdel-Rehim, Mohamed
    Stockholm University, Faculty of Science, Department of Environmental Science and Analytical Chemistry.
    Molecularly imprinted polymer-sol-gel tablet toward micro-solid phase extraction: II. Determination of amphetamine in human urine samples by liquid chromatography tandem mass spectrometry2017In: Journal of chromatography. B, ISSN 1570-0232, E-ISSN 1873-376X, Vol. 1063, p. 130-135Article in journal (Refereed)
    Abstract [en]

    Amphetamine selective molecularly imprinted sol-gel polymer tablets, MIP-tablets, for solid-phase micro extraction of biofluid samples were prepared. An acetonitrile solution of deuterated amphetamine template and silane precursor, 3-(propylmethacrylate) trimethoxysilane, was soaked into the pores of polyethylene tablet substrates and polymerized by an acid-catalysed sol-gel process. Application of the resultant MIP-tablets to extract amphetamine from human urine samples followed by LC-MS/MS analysis was investigated. The extraction protocol was optimised with respect to pH of sample, addition of sodium chloride, extraction time, desorption solvent and desorption time. The final analysis method determined amphetamine in human urine with a limit of detection (LOD) of 1.0 ng/mL and a lower limit of quantification (LLOQ) of 5 ng/mL. Validation demonstrated accuracy of the method was 91.0-104.0% and inter-assay precision was 4.8-8.5% (RSD). Extraction recovery was 80%. The MIP-tablets could be re-used and the same tablet could be employed for more than twenty extractions.

  • 31. Emmer, Mårten
    et al.
    Emmer, Åsa
    Roeraade, Johan
    Lindberg, Ulf
    Hök, Bertil
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Micro vials on a silicon wafer for sample introduction in capillary electrophoresis1992In: Journal of chromatography. B, ISSN 1570-0232, E-ISSN 1873-376XArticle in journal (Refereed)
  • 32.
    Eriksson, Kåre
    et al.
    Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Occupational and Environmental Medicine.
    Östin, Anders
    National Institute for Working Life, Umeå.
    Levin, Jan-Olof
    National Institute for Working Life, Umeå.
    Quantification of melatonin in human saliva by liquid chromatography-tandem mass spectrometry using stable isotope dilution2003In: Journal of chromatography. B, ISSN 1570-0232, E-ISSN 1873-376X, Vol. 794, no 1, p. 115-123Article in journal (Refereed)
    Abstract [en]

    A method for the determination of melatonin in human saliva has been developed using high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS-MS). Saliva was collected in plastic tubes. 7-D-Melatonin was added as internal standard and the samples were cleaned and concentrated by solid-phase extraction. The limit of detection was 1.05 pg x ml(-1) and the limit of quantification was 3.0 pg x ml(-1). The accuracy of the method was +/-14% at 5.60 pg x ml(-1) and +/-9% at 19.6 pg x ml(-1). The precision was +/-13% at 6.18 pg x ml(-1) and +/-11% at 31.2 pg x ml(-1), respectively. Our HPLC-MS-MS method shows a high sensitivity and specificity for melatonin and more reliable results compared with a radioimmunoassay. The chromatographic method has been used to determine the circadian rhythm of melatonin among three nurses working the night shift and a patient suffering from an inability to fall asleep at night.

  • 33.
    Fotoohi, K
    et al.
    Cancercenter KI, Stockholm.
    Skarby, T
    Lund.
    Söderhäll, S
    Karolinska.
    Peterson, Curt
    Linköping University, Faculty of Health Sciences. Linköping University, Department of Medicine and Care, Clinical Pharmacology. Östergötlands Läns Landsting, Centre for Laboratory Medicine, Department of Clinical Pharmacology.
    Albertioni, Freidoun
    Linköping University, Faculty of Health Sciences. Linköping University, Department of Medicine and Care, Clinical Pharmacology.
    Interference of 7-hydroxymethotrexate with the determination of methotrexate in plasma samples from children with acute lymphoblastic leukemia employing routine clinical assays2005In: Journal of chromatography. B, ISSN 1570-0232, E-ISSN 1873-376X, Vol. 817, no 2, p. 139-144Article in journal (Refereed)
    Abstract [en]

    The accuracy of two clinical assays, the enzyme-multiplied immunoassay (EMIT) and fluorescence polarization immunoassay (FPIA2), universally employed for measurement of plasma levels of methotrexate (MTX) in children administered a high dose of this drug for treatment of acute lymphoblastic leukemia was evaluated here. Because of its superior specificity, sensitivity, and precision, high performance liquid chromatography (HPLC) was selected as the reference method with which the other two procedures were compared using approximately 420 different plasma samples for method comparison. 7-Hydroxymethotrexate (7-OHMTX), the major plasma metabolite of MTX, that can be detected in plasma at relatively high concentrations for long periods following infusion of a high dose of MTX, was also quantitated by HPLC. Forty-two and 66 h after infusion, the plasma level of MTX was overestimated in 2% and 3% of the samples by the FPIA2 procedure in 5% and 31% by the EMIT assay. The overall correlation coefficients (r2) for the values obtained by FPIA2 or EMIT versus those based on HPLC were 0.989 and 0.663, respectively. The presence of 7-OHMTX exerted a highly significant influence (p = 0.0007 as determined by the unpaired t-test) on MTX measurement by the EMIT assay. We conclude that the rapid automated procedures routinely used at present and in particular EMIT, suffer from cross-reactivity with metabolites of MTX. Thus, the relatively high percentage of samples in which the level of MTX is overestimated at check-points by EMIT may result in longer periods of hospitalization, higher costs and prolonged administration of elevated doses of "rescue" leucovorin with an increased risk for relapse. © 2004 Elsevier B.V. All rights reserved.

  • 34.
    Foyn Bruun, Cathrine
    Linköping University, Faculty of Health Sciences. Linköping University, Department of Molecular and Clinical Medicine, Pediatrics. Östergötlands Läns Landsting, Centre of Paediatrics and Gynecology and Obstetrics, Barn.
    Enrichment of serum amyloid proteins by hydrophobic interaction chromatography combined with two-dimensional electrophoresis with immobilised pH gradients2003In: Journal of chromatography. B, ISSN 1570-0232, E-ISSN 1873-376X, Vol. 790, no 1-2, p. 355-363Article in journal (Refereed)
    Abstract [en]

    Serum amyloid A protein was subjected to one-step octyl-Sepharose extraction in three different dimensions. Elution was performed partly without UV recording, and with urea or guanidine-based buffers. The eluent was applied directly to denaturing two-dimensional electrophoresis with immobilised pH gradient, or octyl-Sepharose extracted fractions were pooled and lyophilised before application. Proteins were characterised by N-terminal analysis or mass spectrometry. In most of the species that were studied, previously undescribed serum amyloid proteins were detected. Compared to conventional strategies, the presented techniques are more rational and yield more comprehensive information. The presented data also provide a basis for novel perspectives regarding certain inflammatory conditions.

  • 35.
    Garscha, Ulrike
    et al.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Pharmaceutical Biosciences.
    Nilsson, Tomas
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Pharmaceutical Biosciences.
    Oliw, E.H.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Pharmaceutical Biosciences.
    Enantiomeric separation and analysis of unsaturated hydroperoxy fatty acids by chiral column chromatography-mass spectrometry2008In: Journal of chromatography. B, ISSN 1570-0232, E-ISSN 1873-376X, Vol. 872, p. 90-98Article in journal (Refereed)
    Abstract [en]

    Hydroperoxides of 18:2n-6 and 20:4n-6 were obtained by autoxidation and photooxidation. The enantiomers Were separated as free acids (Reprosil Chiral-NR column, eluted with hexane containing 1-1.2% alcoholic modifier) and analyzed by on line UV detection (234 nm) and liquid chromatography-MS/MS/MS of carboxylate anions (A(-) -> (A(-)-18) -> full scan) in an ion trap. The combination of UV and MS/MS/MS analysis facilitated identification of hydroperoxides even in complex mixtures of autoxidized or photooxidized fatty acids. The signal intensities increased about two orders of magnitude by raising the isolation width of A(-) from 1.5 amu to 5 or 10 amu for cis-trans conjugated hydroperoxy fatty acids, and one order of magnitude of more for non-conjugated hydroperoxy fatty acids. The S enantiomer of 8-, 9-, 10-, and 13-hydroperoxyoctadecadienoic acids and the S enantiomer of cis-trans conjugated hydroperoxyeicosatetraenoic acids eluted before the corresponding R enantiomer with two exceptions (11-hydroperoxylinoleic acid and 8-hydroperoxyeicosa-5Z,9E,11Z,14Z-tetraenoic acid). The separation of enantiomers or regioisomers could be improved by the choice of either isopropanol or methanol as alcoholic modifier.

  • 36.
    Gottschalk, Ingo
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Biochemistry.
    Gustavsson, Per-Erik
    Ersson, Bo
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Biochemistry.
    Lundahl, Per
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Surface Biotechnology.
    Improved lectin-mediated immobilization of human red blood cells in superporous agarose beads2003In: Journal of chromatography. B, ISSN 1570-0232, E-ISSN 1873-376X, Vol. 784, no 1, p. 203-208Article in journal (Refereed)
    Abstract [en]

    A new type of agarose bead, superporous agarose, was used as a gel support for immobilization of human red blood cells (RBCs) mediated by wheat germ lectin. The number of immobilized cells was similar to that obtained with commercial wheat germ lectin–agarose but the cell stability appeared to be superior. This allowed improved frontal affinity chromatographic analyses of cytochalasin B (CB)-binding to the glucose transporter GLUT1 which established a ratio of one CB-binding site per GLUT1 dimer for both plain RBCs or those treated with different poly amino acids. The measured dissociation constants, 70±14 nM for CB and 12±3 mM for glucose binding to GLUT1, are similar to those reported earlier.

  • 37.
    Gottschalk, Ingo
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Biochemistry.
    Lagerquist, Caroline
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Biochemistry.
    Zuo, Shu-Sheng
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Biochemistry.
    Lundqvist, Andreas
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Biochemistry.
    Lundahl, Per
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Biochemistry.
    Immobilised biomembrane affinity chromatography for binding studies of membrane proteins2002In: Journal of chromatography. B, ISSN 1570-0232, E-ISSN 1873-376X, Vol. 768, no 1, p. 31-40Article, review/survey (Refereed)
    Abstract [en]

    Analyses of specific interactions between solutes and a membrane protein can serve to characterize the protein. Frontal affinity chromatography of an interactant on a column containing the membrane protein immobilized in a lipid environment is a simple and robust approach for series of experiments with particular protein molecules. Regression analysis of the retention volumes at a series of interactant concentrations shows the affinity of the protein for the interactant and the amount of active binding sites. The higher the affinity, the fewer sites are required to give sufficient retention. Competition experiments provide the affinities of even weakly binding solutes and the non-specific retention of the primary interactant. Hummel and Dreyer size-exclusion chromatography allows complementary analyses of non-immobilized membrane materials. Analyses of the human facilitative glucose transporter GLUT1 by use of the inhibitor cytochalasin B (radioactively labeled) and the competitive substrate D-glucose (non-labeled) showed that GLUT1 interconverted between two states, exhibiting one or two cytochalasin B-binding sites per two GLUTI monomers, dependent on the membrane composition and environment. Similar analyses of a nucleoside transporter, a photosynthetic reaction center, nicotinic acetylcholine receptors and a P-glycoprotein, alternative techniques, and immobilized-liposome chromatographic approaches are presented briefly.

  • 38. Grey, Carl
    et al.
    Edebrink, Per
    Krook, Maria
    Jacobsson, Sven P.
    Stockholm University, Faculty of Science, Department of Analytical Chemistry.
    Development of a high performance anion exchange chromatography analysis for mapping of oligosaccharides2009In: Journal of chromatography. B, ISSN 1570-0232, E-ISSN 1873-376X, Vol. 877, no 20-21, p. 1827-1832Article in journal (Refereed)
    Abstract [en]

    In the present study a HPAEC-PAD method is described that was developed for monitoring the consistency of N-glycosylation during the production and purification of recombinant proteins and monoclonal antibodies. The method successfully separated 18 neutral and sialylated oligosaccharides. Results obtained were compared with MALDI-TOF MS and it was shown that both methods gave similar results. in addition, a method validation was performed showing that the HPAEC-PAD analysis was well suited for the mapping and characterization of oligosaccharides. The method was found to be robust and additionally the precision was significantly better compared to the MALDI-TOF MS method. 

  • 39.
    Haglind, Alfred
    et al.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Medicinal Chemistry.
    Hedeland, Mikael
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Medicinal Chemistry. National Veterinary Institute (SVA), Dept. of Chemistry, Environment and Feed Hygiene, Uppsala, Sweden.
    Arvidsson, Torbjörn
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Medicinal Chemistry. Medical Products Agency, Uppsala, Sweden.
    Pettersson, Curt E
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Medicinal Chemistry.
    Major signal suppression from metal ion clusters in SFC/ESI-MS: Cause and Effects2018In: Journal of chromatography. B, ISSN 1570-0232, E-ISSN 1873-376X, Vol. 1084, p. 96-105Article in journal (Refereed)
    Abstract [en]

    The widening application area of SFC-MS with polar analytes and water-containing samples facilitates the use of quick and simple sample preparation techniques such as “dilute and shoot” and protein precipitation. This has also introduced new polar interfering components such as alkali metal ions naturally abundant in e.g. blood plasma and urine, which have shown to be retained using screening conditions in SFC/ESI-TOF-MS and causing areas of major ion suppression. Analytes co-eluting with these clusters will have a decreased signal intensity, which might have a major effect on both quantification and identification. When investigating the composition of the alkali metal clusters using accurate mass and isotopic pattern, it could be concluded that they were previously not described in the literature. Using NaCl and KCl standards and different chromatographic conditions, varying e.g. column and modifier, the clusters proved to be formed from the alkali metal ions in combination with the alcohol modifier and make-up solvent. Their compositions were [(XOCH3)n+X]+, [(XOH)n+X]+, [(X2CO3)n+X]+ and [(XOOCOCH3)n+X]+ for X= Na+ or K+ in ESI+. In ESI-, the clusters depended more on modifier, with [(XCl)n+Cl]- and [(XOCH3)n+OCH3]- mainly formed in pure methanol and [(XOOCH)n+OOCH]- when 20 mM NH4Fa was added.

    To prevent the formation of the clusters by avoiding methanol as modifier might be difficult, as this is a widely used modifier providing good solubility when analyzing polar compounds in SFC. A sample preparation with e.g. LLE would remove the alkali ions, however also introducing a time consuming and discriminating step into the method. Since the alkali metal ions were retained and affected by chromatographic adjustments as e.g. mobile phase modifications, a way to avoid them could therefore be chromatographic tuning, when analyzing samples containing them.

  • 40.
    Hansson, Annelie
    et al.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Medicinal Chemistry, Analytical Science.
    Knych, Heather
    Stanley, Scott
    Berndtson, Emma
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Medicinal Chemistry, Analytical Science. Natl Vet Inst SVA, Dept Chem Environm & Feed Hyg, SE-75651 Uppsala, Sweden.
    Jackson, Liora
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Medicinal Chemistry, Analytical Science. Natl Vet Inst SVA, Dept Chem Environm & Feed Hyg, SE-75651 Uppsala, Sweden.
    Bondesson, Ulf
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Medicinal Chemistry, Analytical Science. Natl Vet Inst SVA, Dept Chem Environm & Feed Hyg, SE-75651 Uppsala, Sweden.
    Thevis, Mario
    Hedeland, Mikael
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Medicinal Chemistry, Analytical Science. Natl Vet Inst SVA, Dept Chem Environm & Feed Hyg, SE-75651 Uppsala, Sweden.
    Equine in vivo-derived metabolites of the SARM LGD-4033 and comparison with human and fungal metabolites.2018In: Journal of chromatography. B, ISSN 1570-0232, E-ISSN 1873-376X, Vol. 1074-1075, p. 91-98Article in journal (Refereed)
    Abstract [en]

    LGD-4033 has been found in human doping control samples and has the potential for illicit use in racehorses as well. It belongs to the pharmacological class of selective androgen receptor modulators (SARMs) and can stimulate muscle growth, much like anabolic steroids. However, SARMs have shown superior side effect profiles compared to anabolic steroids, which arguably makes them attractive for use by individuals seeking an unfair advantage over their competitors. The purpose of this study was to investigate the metabolites formed from LGD-4033 in the horse in order to find suitable analytical targets for doping controls. LGD-4033 was administered to three horses after which plasma and urine samples were collected and analyzed for metabolites using ultra high performance liquid chromatography coupled to a high resolution mass spectrometer. In horse urine, eight metabolites, both phase I and phase II, were observed most of which had not been described in other metabolic systems. Six of these were also detected in plasma. The parent compound was detected in plasma, but not in non-hydrolyzed urine. The longest detection times were observed for unchanged LGD-4033 in plasma and in urine hydrolyzed with β-glucuronidase and is thus suggested as the analytical target for doping control in the horse. The metabolite profile determined in the horse samples was also compared to those of human urine and fungal incubate from Cunninghamella elegans. The main human metabolite, dihydroxylated LGD-4033, was detected in the horse samples and was also produced by the fungus. However, it was a not a major metabolite for horse and fungus, which highlights the importance of performing metabolism studies in the species of interest.

  • 41. Hedeland, Mikael
    et al.
    Fredriksson, Elisabeth
    Lennernäs, Hans
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Pharmacy.
    Bondesson, Ulf
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Medicinal Chemistry.
    Simultaneous quantification of the enantiomers of verapamil and its N-demethylated metabolite in human plasma using liquid chromatography-tandem mass spectrometry2004In: Journal of chromatography. B, ISSN 1570-0232, E-ISSN 1873-376X, Vol. 804, no 2, p. 303-311Article in journal (Refereed)
    Abstract [en]

    A stereoselective bioanalytical method for the simultaneous quantification of the enantiomers of verapamil and its active main metabolite norverapamil in human plasma has been developed and validated. The samples were analysed by liquid chromatography-electrospray-tandem mass spectrometry (LC-ESI-MS/MS) in the Selected Reaction Monitoring (SRM) mode using a deuterated internal standard. The stationary phase used for the chiral separation was a Chiral-AGP. The enantiomers of verapamil were selectively detected from those of norverapamil by the mass spectrometer due to different molecular masses, although there was a chromatographic co-elution. Thus, time-consuming procedures like achiral preseparation or chemical derivatisation could be avoided. Higher detection sensitivity than earlier published methods based on fluorescence detection was obtained, although a mobile phase of high water-content and high flow-rate was introduced into the electrospray interface (85% aqueous ammonium acetate pH 7.4 +15% acetonitrile at 0.6 ml/min). The enantiomers of verapamil and norverapamil could be quantified at levels down to 50 pg and 60 pg/500 microl plasma sample, respectively, with R.S.D. in the range of 3.6-7.8%. The presented method was successfully applied to an in vivo intestinal absorption and bioavailability study in humans, using the Loc-I-Gut method.

  • 42. HJemdahl, P
    et al.
    Larsson, T
    Bradley, T
    Åkerstedt, T
    Anderzén, Ingrid
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Public Health and Caring Sciences.
    Sigurson, K
    Gillberg, M
    Lundberg, Ulf
    Catecholamine measurements in urine by high-performance liquid chromatography with amperometric detection--comparison with an autoanalyser fluorescence method.1989In: Journal of chromatography. B, ISSN 1570-0232, E-ISSN 1873-376XArticle in journal (Refereed)
  • 43.
    Hober, Sophia
    et al.
    KTH, School of Biotechnology (BIO), Proteomics (closed 20130101).
    Nord, Karin
    Linhult, Martin
    Protein A chromatography for antibody purification2007In: Journal of chromatography. B, ISSN 1570-0232, E-ISSN 1873-376X, Vol. 848, no 1, p. 40-47Article, review/survey (Refereed)
    Abstract [en]

    Staphylococcal protein A (SPA) is one of the first discovered immunoglobulin binding molecules and has been extensively studied during the past decades. Due to its affinity to immunoglobulins, SPA has found widespread use as a tool in the detection and purification of antibodies and the molecule has been further developed to one of the most employed affinity purification systems. Interestingly, a minimized SPA derivative has been constructed and a domain originating from SPA has been improved to withstand the harsh environment employed in industrial purifications. This review will focus on the development of different affinity molecules and matrices for usage in antibody purification.

  • 44. Homer, Natalie Z M
    et al.
    Reynolds, Rebecca M
    Mattsson, Cecilia
    Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Medicine.
    Bailey, Matthew A
    Walker, Brian R
    Andrew, Ruth
    Quantitative analysis of RU38486 (mifepristone) by HPLC triple quadrupole mass spectrometry2009In: Journal of chromatography. B, ISSN 1570-0232, E-ISSN 1873-376X, Vol. 877, no 5-6, p. 497-501Article in journal (Refereed)
    Abstract [en]

    A sensitive liquid chromatography-mass spectrometric method was validated for the quantification of RU38486 (mifepristone) in human and murine plasma. The analyte and internal standard (alfaxolone) were extracted by liquid-liquid extraction with diethyl ether, resolved on a C18 column using gradient elution with methanol and ammonium acetate and detected after positive electrospray ionization (m/z 430-->372; m/z 333-->297, respectively). Quantification was linear over the range 0.5-500ng (r(2)>0.997), precise and accurate (intra-assay RSD</=7.2%, RME</=8.2%; inter-assay RSD</=15.7% RME</=10.2%). The limit of quantification (LOQ) was 50pg injected on column, permitting reproducible analysis of RU38486 in small volumes of plasma.

  • 45.
    Höjer Holmgren, Karin
    et al.
    FOI Swedish Defence Research Agency, Sweden.
    Gustafsson, Tomas
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Processum. FOI Swedish Defence Research Agency, Sweden.
    Östin, Anders
    FOI Swedish Defence Research Agency, Sweden.
    Screening of nerve agent markers with hollow fiber-chemosorption of phosphonic acids2016In: Journal of chromatography. B, ISSN 1570-0232, E-ISSN 1873-376X, Vol. 1033-1034, p. 97-105Article in journal (Refereed)
    Abstract [en]

    This report describes a method developed for extracting nerve gas markers such as phosphonic acids from urine and other aqueous samples. It involves single-step microextraction with chemosorption to hollow fibers that have been pre-soaked in a solution containing a derivatization reagent (3,5 triflouro methyl benzene diazomethane). The derivatives it forms with phosphonic acids can be sensitively detected by mass spectrometric detectors operating in negative chemical ionization (NCI) mode. Limits of quantification obtained in analyses of water and urine extracts by GC/MS in negative chemical ionization and selected ion monitoring mode were 0.1–10 and 0.5–10 ng/mL, respectively. Pentaflourophenyl diazomethane can also be used as a derivatization reagent, and the micro-extracts (which generate low background signals) can be sensitively analyzed by GC–MS/MS in NCI selected reaction monitoring (SRM) mode, using two specific transitions for both reagents. Thus, this sensitive approach can be flexibly modified to obtain confirmatory information, or address potential problems caused by interferences in some samples.

  • 46.
    Idborg, Helena
    et al.
    Stockholm University, Faculty of Science, Department of Analytical Chemistry.
    Zamani, Leila
    Edlund, Per-Olof
    Schuppe-Koistinen, Ina
    Jacobsson, Sven P.
    Stockholm University, Faculty of Science, Department of Analytical Chemistry.
    Metabolic fingerprinting of rat urine by LC/MS. Part 1. Analysis by hydrophilic interaction liquid chromatography-electrospray ionization mass spectrometry2005In: Journal of chromatography. B, ISSN 1570-0232, E-ISSN 1873-376X, Vol. 828, no 1-2, p. 9-13Article in journal (Refereed)
  • 47.
    Ihalin, R
    et al.
    Umeå University, Faculty of Medicine, Odontology, Oral Microbiology.
    Karched, M
    Umeå University, Faculty of Medicine, Odontology, Oral Microbiology.
    Eneslätt, Kjell
    Umeå University, Faculty of Medicine, Odontology, Oral Microbiology.
    Asikainen, Sirkka
    Umeå University, Faculty of Medicine, Odontology, Oral Microbiology.
    Characterization of immunoaffinity purified peptidoglycan-associated lipoprotein of Actinobacillus actinomycetemcomitans.2006In: Journal of chromatography. B, ISSN 1570-0232, E-ISSN 1873-376X, Vol. 831, no 1-2, p. 116-125Article in journal (Refereed)
    Abstract [en]

    Peptidoglycan-associated lipoprotein (PAL) is a highly conserved structural outer membrane protein among Gram-negative bacteria. In some species, it is proinflammatory and released extracellularly. We purified a newly identified PAL (AaPAL) of a periodontal pathogen Actinobacillus actinomycetemcomitans by using AaPAL antipeptide antibodies coupled to immunoaffinity chromatography column. No protein impurities originating in A. actinomycetemcomitans were found in the final product. Sera from patients infected by A. actinomycetemcomitans recognized the purified AaPAL. The present purification method seems to be suitable for isolation of AaPAL and probably PALs of other bacterial species, and applicable in studies investigating proinflammatory mechanisms of A. actinomycetemcomitans.

  • 48.
    Jacksén, Johan
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Analytical Chemistry.
    Dahl, Kenneth
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Analytical Chemistry.
    Karlberg, Ann-Therese
    Redeby, Theres
    Emmer, Åsa
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Analytical Chemistry.
    Capillary electrophoresis separation and matrix-assisted laser desorption/ionization mass spectrometry characterization of bovine serum albumin fluorescein isothiocyanate conjugates2010In: Journal of chromatography. B, ISSN 1570-0232, E-ISSN 1873-376X, Vol. 878, no 15-16, p. 1125-1134Article in journal (Refereed)
    Abstract [en]

    A protocol using enzymatic digestion, matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF-MS) and capillary electrophoresis with laser induced fluorescence detection (CE-LIF) for the investigation of the binding of the fluorescent contact allergen fluorescein isothiocyanate (FITC) to the 66 kDa large protein bovine serum albumin (BSA), as a model system for protein-hapten binding in the skin, is presented. Mass spectra of BSA-FITC digestions, using trypsin and chymotrypsin, respectively, provided sequence coverage of 97%. To investigate the number of FITC-bound peptides using CE-LIF separation, three different buffer salts at four different pH levels were evaluated. The use of 20 mM sodium citrate pH 6.5 as well as 20 mM sodium phosphate pH 6.5 or pH 7.5 as background electrolyte revealed high numbers of peptides with at least one bound FITC. The effect of the electrolyte counter ion on MALDI-MS was investigated and was found to have effect on the MALDI spectra signal-to-noise (S/N) at 50 mM but not at 10 m M. Of the 60 theoretical FITC-binding sites in BSA this MALDI-MS protocol presents 30 defined. 28 possible and 2 non-binding sites for FITC. (C) 2010 Elsevier B.V. All rights reserved.

  • 49.
    Jansson, Britt
    et al.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Pharmaceutical Biosciences, Division of Pharmacokinetics and Drug Therapy.
    Simonsson, Ulrika S H
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Pharmaceutical Biosciences, Division of Pharmacokinetics and Drug Therapy.
    Ashton, Michael
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Pharmaceutical Biosciences, Division of Pharmacokinetics and Drug Therapy.
    Simultaneous enantiospecific separation and quantitation of mephenytoin and its metabolites nirvanol and 4'-hydroxymephenytoin in human plasma by liquid chromatography2003In: Journal of chromatography. B, ISSN 1570-0232, E-ISSN 1873-376X, Vol. 791, no 1-2, p. 179-191Article in journal (Refereed)
    Abstract [en]

    A high-performance liquid chromatographic method for the enantiospecific quantitation of S- and R-mephenytoin and its metabolites S- and R-nirvanol and S- and R-4'-hydroxymephenytoin in plasma is described. The compounds were separated using a reversed-phase C(2) column in tandem with a chiral alpha(1)-acid glycoprotein column and were detected using ultraviolet detection at 205 nm. The lower limit of quantification was 10 ng/ml for all compounds using 0.5 ml human plasma (intra-day coefficient of variation <13%, accuracy <+/-20%). The method was validated for human plasma in the concentration range 10-2000 ng/ml for each of the six compounds. The method allows for the simultaneous characterisation of the metabolic capacity of two human drug-metabolising enzymes, CYP2C19 and CYP2B6, and may be used when investigating polymorphisms or changes in activity of these two enzymes.

  • 50. Jansson, M
    et al.
    Emmer, Å
    Roeraade, J
    Lindberg, U
    Hök, Bertil
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Micro vials on a silicon wafer for sample introduction in capillary electrophoreses1992In: Journal of chromatography. B, ISSN 1570-0232, E-ISSN 1873-376XArticle in journal (Refereed)
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