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  • 1.
    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.

  • 2.
    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.

  • 3.
    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.

  • 4. 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.

  • 5.
    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.

  • 6.
    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.

  • 7.
    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.

  • 8.
    Karim, Hazhar
    et al.
    Karolinska Institutet, Karolinska University Hospital, Stockholm, Sweden.
    Lindqvist Appell, Malin
    Linköping University, Department of Medical and Health Sciences, Division of Drug Research. Linköping University, Faculty of Health Sciences.
    Fotoohi, Alan
    Karolinska Institutet, Karolinska University Hospital, Stockholm, Sweden.
    Comparison of three methods for measuring thiopurine methyltransferase activity in red blood cells and human leukemia cells2013In: Journal of chromatography. B, ISSN 1570-0232, E-ISSN 1873-376X, Vol. 939, p. 80-85Article in journal (Refereed)
    Abstract [en]

    Thiopurine efficacy is partly reflected by the genetic polymorphism of the thiopurine methyltransferase (TPMT) enzyme, which is responsible for variation in the metabolism, toxicity and therapeutic efficacy of the thiopurines azathioprine (AZA), 6-mercaptopurine (6-MP) and 6-thioguanine (6-TG). Determination of TPMT activity before administration of thiopurines is thus crucial for individualized dosing in order to prevent toxicity in TPMT deficient individuals. These individuals must be treated with markedly lower (eg, 5-10% of the standard) doses of the prescribed medications. This paper describes a comparison of three different methods for the quantification of TPMT activity in red blood cells (RBC) and cultured human cell lines. We succeeded to perform the measurement of TPMT activity in a minimum amount of 1×10(6) cultured cells with an HPLC-UV system modified and optimized in our laboratory. The TPMT activity was linearly correlated with the cell concentration of the cultured cell line in a range of 1-10×10(6) cells. A significant correlation of determination of TPMT activity in RBC between radiometric detection by HPLC, classic radiochemical detection and UV detection by HPLC, was observed, correlation coefficient (r) were 0.72 and 0.73, respectively. The within-day and day-to-day coefficients of variation of the HPLC-UV-based method were 8% and 16%, respectively. The evaluation of the methods was demonstrated by studying the TPMT activity in RBC isolated from 198 patients, as well as in MOLT4 leukemic cell line and its sub-cell lines with acquired resistance to 6-MP and 6-TG.

  • 9. Knutsen Holmqvist, Annica
    et al.
    Adell, Gunnar
    Linköping University, Department of Medical and Health Sciences. Linköping University, Faculty of Health Sciences.
    Sun, Xiao-Feng
    Roman, M
    Nationall Board Forensic Medicine .
    Survivin expression is an independent prognostic factor in rectal cancer patients with and without preoperative radiotherapy2004In: Journal of chromatography. B, ISSN 1570-0232, E-ISSN 1873-376X, Vol. 60, no 1, p. 149-155Article in journal (Refereed)
    Abstract [en]

    Purpose: Survivin, as an inhibitor of apoptosis, is undetectable in normal tissues but expressed in tumors. Survivin expression in rectal cancer patients who have undergone preoperative radiotherapy (RT) alone has not been studied. We analyzed the relationships of survivin expression to RT, clinicopathologic variables, apoptosis, and p53 expression in rectal cancer patients who participated in a trial of preoperative RT. Methods and Materials: Survivin was immunohistochemically examined in 98 rectal tumors (74 had adjacent normal mucosa). Of 98 patients, 57 underwent surgery alone and 41 underwent RT before surgery. Results: Survivin positivity was related to worse survival, independent of Dukes' stage, local and distant recurrence, differentiation, gender, age, apoptosis, and p53 expression (p = 0.02). Survivin was not associated with survival in the patients without (p = 0.08) or with (p = 0.19) RT. After RT, survivin tended to be increased in adjacent normal mucosa (p = 0.057) but not in tumors (p = 0.71). Conclusion: Survivin was independently related to survival in rectal cancer patients who participated in a trial of preoperative RT, but not in either treatment group (surgery alone or surgery plus RT). Whether the effect of survivin on tumors is associated with RT and further related to patient survival needs to be investigated in a larger number of patients. (C) 2004 Elsevier Inc.

  • 10.
    Magiera, Sylwia
    et al.
    Silesian Technical University, Poland .
    Baranowska, Irena
    Silesian Technical University, Poland .
    Kusa, Jacek
    Regional Specialist Hospital, Poland .
    Baranowski, Jacek
    Östergötlands Läns Landsting, Heart and Medicine Centre, Department of Clinical Physiology UHL.
    A liquid chromatography and tandem mass spectrometry method for the determination of potential biomarkers of cardiovascular disease2013In: Journal of chromatography. B, ISSN 1570-0232, E-ISSN 1873-376X, Vol. 919, p. 20-29Article in journal (Refereed)
    Abstract [en]

    A simple, accurate and sensitive liquid chromatography tandem mass spectrometry (LC-MS/MS) method was developed and validated for the quantitation of alpha-ketoglutaric acid (alpha-KG), L-carnitine (L-CAR) and acetyl-L-carnitine (acetyl-L-CAR) in human urine as potential biomarkers of cardiovascular disease. The separation was performed using an isocratic elution of 0.1% formic acid in water and acetonitrile (97:3, v/v) on an Acclaim 120 C8 column (150 mm x 4.6 mm, 3.0 mu m). The flow rate of the mobile phase was 1.2 mL/min and the total assay run time was 3 min. Detection was performed on a triple-quadrupole mass spectrometer in selected reaction monitoring (SRM) mode via an electrospray ionization (ESI) source in positive and negative ion modes. This method covered a linearity range of 0.1-500 ng/mL for L-CAR and acetyl-L-CAR and 1-1000 ng/mL for alpha-KG with lower limits of quantification (LLOQ) of 0.08 ng/mL for L-CAR, 0.04 ng/mL for acetyl-L-CAR and 0.8 ng/mL for alpha-KG. The intra-day and inter-day precision and accuracy of the quality control samples exhibited relative standard deviations of less than 5.54% and relative error values from -5.95% to 3.11%. Analyte stability was evaluated under various sample preparation, analysis and storage conditions and varied from -9.89% to -0.47%. A two-step solid-phase extraction (SPE) procedure using silica gel and quaternary amine cartridges was used for urine sample cleanup. The average recoveries for all analyzed compounds were better than 86.64% at three concentrations. The method was successfully applied for the quantitation of alpha-KG, L-CAR and acetyl-L-CAR in human urine samples.

  • 11.
    Magiera, Sylwia
    et al.
    Silesian Technical University, Poland .
    Hejniak, Judyta
    Silesian Technical University, Poland .
    Baranowski, Jacek
    Östergötlands Läns Landsting, Heart and Medicine Center, Department of Clinical Physiology in Linköping.
    Comparison of different sorbent materials for solid-phase extraction of selected drugs in human urine analyzed by UHPLC-UV2014In: Journal of chromatography. B, ISSN 1570-0232, E-ISSN 1873-376X, Vol. 958, p. 22-28Article in journal (Refereed)
    Abstract [en]

    A procedure based on solid-phase extraction (SPE) followed by ultra-high-performance liquid chromatography (UHPLC) with UV detection has been developed for the analysis of multiple drugs in human urine. The compounds evaluated were aliskiren, prasugrel, rivaroxaban, prednisolone, propranolol, ketoprofen, nifedipine, naproxen, terbinafine, ibuprofen, diclofenac, sildenafil and acenocoumarol. Seventeen different solid phase extraction (SPE) cartridges were tested to evaluate their applicability for the isolation of drugs from human urine. Comparison were recovery of different drugs and reproducibility. The samples were analyzed by UHPLC using a Poroshell 120 EC-C18 column and acetonitrile -0.05% TFA in water as the mobile phase under gradient elution conditions. SPE combined with UHPLC UV allowed the determination of drugs over a linear range of 0.01-30.0 mu g/mL, with limits of detection at 0.003-0.217 mu g/mL and precision of 0.8-7.1%. Phenyl (C6H5) sorbent was found to provide the most effective clean-up, removing the greatest amount of interfering substance and simultaneously ensuring analyte recoveries higher than 85.5% with relative standard deviations (RSD)less than10%. The method was applied with good accuracy and precision in the determination of drugs in human urine obtained from patients treated with selected drugs.

  • 12.
    Magiera, Sylwia
    et al.
    Silesian Technical University, Poland.
    Kolanowska, Anna
    Silesian Technical University, Poland.
    Baranowski, Jacek
    Linköping University, Department of Medical and Health Sciences, Division of Cardiovascular Medicine. Linköping University, Faculty of Medicine and Health Sciences. Region Östergötland, Heart and Medicine Center, Department of Clinical Physiology in Linköping.
    Salting-out assisted extraction method coupled with hydrophilic interaction liquid chromatography for determination of selected beta-blockers and their metabolites in human urine2016In: Journal of chromatography. B, ISSN 1570-0232, E-ISSN 1873-376X, Vol. 1022, p. 93-101Article in journal (Refereed)
    Abstract [en]

    In this study, a new analytical method was developed and validated for the simultaneous analysis of beta-blockers (metoprolol, propranolol, carvedilol) and their metabolites (5-hydroxycarvedilol, O-desmethylcarvedilol, alpha-hydroxymetoprolol, O-desmethylmetoprolol, 5-hydroxypropranolol) in human urine. A salting-out assisted liquid-liquid extraction (SALLE) procedure was used for sample preparation. Several parameters affecting the extraction efficiency and method sensitivity including the type and volume of the extraction solvent, the type and quantity of the inorganic salt, extraction time and sample pH were investigated. Hydrophilic interaction liquid chromatography-ultraviolet detection (HILIC-UV) was used for the determination of allanalytes. During method development, the effects of mobile phase components (type, pH, concentration of salt, organic modifier type and content, flow rate, column temperature) on the retention and separation of beta-blockers and metabolites on the five different HILIC columns were examined. The method was linear for concentrations ranging from 0.1 to 8.0 mu g/mL, with determination coefficients higher than 0.993 for all analytes. The limits of quantification were in the range from 0.1 to 0.2 mu g/mL. Intra- and inter-day precision ranged from 0.1 to 8.9%, and accuracy was within +/- 13% interval for all analytes. Under the optimized conditions, extraction efficiency was greater than 83.4% for determined compounds. The validated method was then applied to the measurement of beta-blockers and their metabolites in human urine samples. (C) 2016 Elsevier B.V. All rights reserved.

  • 13.
    Stephanson, Nikolai
    et al.
    Karolinska Institute.
    Josefsson, Martin
    National Board for Forensic Medicine.
    Kronstrand, Robert
    Linköping University, Department of Medical and Health Sciences, Division of Drug Research. Linköping University, Faculty of Health Sciences.
    Beck, Olof
    Karolinska Institute.
    Accurate identification and quantification of 11-nor-Delta(9)-tetrahydrocannabinol-9-carboxylic acid in urine drug testing: Evaluation of a direct high efficiency liquid chromatographic-mass spectrometric method2008In: Journal of chromatography. B, ISSN 1570-0232, E-ISSN 1873-376X, Vol. 871, no 1, p. 101-108Article in journal (Refereed)
    Abstract [en]

    A direct liquid chromatographic-tandem mass spectrometric (LC-MS/MS) method for measurement of urinary Delta(9)-tetrahydrocannabinol carboxylic acid (THCA) was developed. The method involved dilution of the urine sample with water containing H-2(9)-deuterated analogue as internal standard, hydrolysis with ammonia, reversed phase chromatography using a Waters ultra-performance liquid chromatography (UPLC (TM)) equipment with gradient elution, negative electrospray ionization, and monitoring of two product ions in selected reaction monitoring mode. The measuring range was 2-1000 ng/mL for THCA, and the intra- and inter-assay imprecision, expressed as the coefficient of variation, was below 5%. Influence from urine matrix on ionization efficiency was noted in infusion experiments, but was compensated for by the internal standard. Comparison with established gas chromatography-mass spectrometry and liquid chromatography-mass spectrometry methods in authentic patient samples demonstrated accuracy in both qualitative and quantitative results. A small difference in mean ratios (similar to 15%) may be explained by the use of different hydrolysis procedures between methods. In conclusion, the high efficiency LC-MS/MS method was capable of accurately identify and quantify THCA in urine with a capacity of 14 samples per hour.

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