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1.	Petersson, Patrik, et al. (författare) Why ultra high performance liquid chromatography produces more tailing peaks than high performance liquid chromatography, why it does not matter and how it can be addressed 2011 Ingår i: Journal of chromatography. B. - : Elsevier BV. - 1570-0232 .- 1873-376X .- 0021-9673 .- 1873-3778. ; 1218:39, s. 6914-6921 Tidskriftsartikel (refereegranskat)abstract The purpose of this study is to demonstrate, with experiments and with computer simulations based on a firm chromatographic theory, that the wide spread perception of that the United States Pharmacopeia tailing factor must be lower than 2 (Tf < 2) is questionable when using the latest generation of LC equipment. It is shown that highly efficient LC separations like those obtained with sub-2 μm porous and 2.7 μm superficially porous particles (UHPLC) produce significantly higher Tf-values than the corresponding separation based on 3 μm porous particles (HPLC) when the same amount of sample is injected. Still UHPLC separations provide a better resolution to adjacent peaks. Expressions have been derived that describe how the Tf-value changes with particle size or number of theoretical plates. Expressions have also been derived that can be used to scale the injection volume based on particle size or number of theoretical plates to maintain the Tf-value when translating a HPLC separation to the corresponding UHPLC separation. An aspect that has been ignored in previous publications. Finally, data obtained from columns with different age/condition indicate that Tf-values should be complemented by a peak width measure to provide a more objective quality measure.
2.	Abdel–Khalik, Jonas, et al. (författare) Development of a solid phase extraction method for the simultaneous determination of steroid hormones in H295R cell line using liquid chromatography–tandem mass spectrometry 2013 Ingår i: Journal of chromatography. B. - 1570-0232 .- 1873-376X. ; 935:September, s. 61-69 Tidskriftsartikel (refereegranskat)abstract 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.
3.	Abdel–Khalik, Jonas, et al. (författare) Simultaneous determination of endogenous steroid hormones in human and animal plasma and serum by liquid or gas chromatography coupled to tandem mass spectrometry 2013 Ingår i: Journal of chromatography. B. - 1570-0232 .- 1873-376X. ; 928:June, s. 59-77 Tidskriftsartikel (refereegranskat)abstract 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.
4.	Al-Saffar, Y, et al. (författare) Multicomponent LC-MS/MS screening method for detection of new psychoactive drugs, legal highs, in urine-experience from the Swedish population 2013 Ingår i: Journal of chromatography. B, Analytical technologies in the biomedical and life sciences. - : Elsevier BV. - 1873-376X. ; 930, s. 112-120 Tidskriftsartikel (refereegranskat)
5.	Amelina, Hanna, et al. (författare) Quantitative subproteomic analysis of age-related changes in mouse liver peroxisomes by iTRAQ LC-MS/MS 2011 Ingår i: Journal of chromatography. B. - : Elsevier BV. - 1570-0232 .- 1873-376X. ; 879:30, s. 3393-3400 Tidskriftsartikel (refereegranskat)abstract 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.
6.	Bankefors, Johan, et al. (författare) Multidimensional profiling of components in complex mixtures of natural products for metabolic analysis, proof of concept: Application to Quillaja saponins 2010 Ingår i: Journal of Chromatography B. - : Elsevier BV. - 1570-0232 .- 1873-376X. ; 878, s. 471-476 Tidskriftsartikel (refereegranskat)abstract A method for separation and detection of major and minor components in complex Mixtures has been developed, utilising two-dimensional high-performance liquid chromatography (2D-HPLC) combined with electrospray ionisation ion-trap multiple-stage mass spectrometry (ESI-ITMS(n)). Chromatographic conditions were matched with mass spectrometric detection to maximise the number of components that could be separated. The described procedure has proven useful to discern several hundreds of saponin components when applied to Quillaja saponaria Molina bark extracts. The discrimination of each saponin component relies oil the fact that three coordinates (x,y,z) for each component can be derived from the retention time of the two chromatographic steps (x,y) and the M/Z-values from the multiple-stage mass spectrometry (z(n), n = 1, 2....). Thus an improved graphical representation was obtained by combining retention times from the two-stage separation with +MS(1) (z(1)) and the additional structural information from the second mass stage +MS(2) (z(2), z(3)) corresponding to the main fragment ions. By this approach three-dimensional plots can be made that reveal both the chromatographic and structural properties of a specific mixture which can be useful in fingerprinting of complex mixtures. (C) 2009 Elsevier B.V. All rights reserved.
7.	Baranowska, Irena, et al. (författare) Clinical applications of fast liquid chromatography: A review on the analysis of cardiovascular drugs and their metabolites 2013 Ingår i: Journal of chromatography. B. - : Elsevier. - 1570-0232 .- 1873-376X. ; 927:SI, s. 54-79 Forskningsöversikt (refereegranskat)abstract 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.
8.	Beck, O, et al. (författare) Method for determination of methadone in exhaled breath collected from subjects undergoing methadone maintenance treatment 2010 Ingår i: Journal of chromatography. B, Analytical technologies in the biomedical and life sciences. - : Elsevier BV. - 1873-376X. ; 878:24, s. 2255-2259 Tidskriftsartikel (refereegranskat)
9.	Bergström, Maria, et al. (författare) Elucidating the selectivity of recombinant forms of Aleuria aurantia lectin using weak affinity chromatography 2012 Ingår i: Journal of chromatography. B. - : Elsevier. - 1570-0232 .- 1873-376X. ; 885, s. 66-72 Tidskriftsartikel (refereegranskat)abstract 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.
10.	Casas, Monica Escolà, et al. (författare) Analytical sample preparation strategies for the determination of antimalarial drugs in human whole blood, plasma and urine 2014 Ingår i: Journal of chromatography. B. - 1570-0232 .- 1873-376X. ; 962, s. 109-131 Tidskriftsartikel (refereegranskat)abstract 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
11.	Dalpiaz, Alessandro, et al. (författare) Quantitative determination of zolmitriptan in rat blood and cerebrospinal fluid by reversed phase HPLC-ESI-MS/MS analysis : application to in vivo preclinical pharmacokinetic study 2012 Ingår i: Journal of chromatography. B. - : Elsevier BV. - 1570-0232 .- 1873-376X. ; 901, s. 72-78 Tidskriftsartikel (refereegranskat)abstract 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.
12.	Davids, Mariska, et al. (författare) 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 spectrometry 2012 Ingår i: Journal of chromatography. B. - : Elsevier BV. - 1570-0232 .- 1873-376X. ; 900, s. 38-47 Tidskriftsartikel (refereegranskat)abstract 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.
13.	Ekman, Eva, et al. (författare) Determination of 5-hydroxythiabendazole in human urine as a biomarker of exposure to thiabendazole using LC/MS/MS. 2014 Ingår i: Journal of Chromatography. B. - : Elsevier BV. - 1873-376X .- 1570-0232. ; 973, s. 61-67 Tidskriftsartikel (refereegranskat)abstract Thiabendazole (TBZ) is widely used as a pre-planting and post-harvest agricultural fungicide and as an anthelminthic in humans and animals. TBZ is of toxicological concern, since adverse effects including nephrogenic, hepatogenic, teratogenic and neurological effects have been reported in mammals. Occupational exposure can occur among agricultural workers and the general public may be environmentally exposed to TBZ through the diet. The metabolite 5-hydroxythiabendazole (5-OH-TBZ) was chosen as biomarker of exposure to TBZ and a LC/MS/MS method for the quantification of 5-OH-TBZ in human urine was developed. The method includes enzyme hydrolysis, as 5-OH-TBZ is conjugated to glucuronide and sulphate in urine. Sample through put was optimised using 96-well plates for sample handling as well as for solid phase extraction (SPE). The method has excellent, within-run, between-run and between-batch precision between 4 and 9%. The limit of detection (LOD) of 0.05 and a limit of quantification (LOQ) of 0.13ng 5-OH-TBZ/mL urine enable detection in environmentally exposed populations. When applying the method in a general Swedish population, 52% had levels above LOD. The method was also applied in one oral and one dermal human experimental exposure study in two individuals. After oral exposure, the excretion of 5-OH-TBZ in urine was described by a two-compartment model and both the first rapid and the second slower elimination phase followed first-order kinetics, with estimated elimination half-life of 2h and 9-12h. The recoveries in urine were between 21 and 24% of the dose. Dermal exposure was described by a one compartment model and followed first order kinetics, with estimated elimination half-life of 9-18h. The recovery in urine was 1% of the administrated dose of TBZ. Although these studies are limited to two individuals, the data provide new basic information regarding the toxicokinetics of TBZ after oral and dermal exposure.
14.	Ekman, Eva, et al. (författare) High-throughput method for the analysis of ethylenethiourea with direct injection of hydrolysed urine using online on-column extraction liquid chromatography and triple quadrupole mass spectrometry. 2013 Ingår i: Journal of Chromatography. B. - : Elsevier BV. - 1873-376X .- 1570-0232. ; 934:Jul,5, s. 53-59 Tidskriftsartikel (refereegranskat)abstract Ethylenethiourea (ETU) is of major toxicological concern, since in experimental animal studies, ETU has shown a large spectrum of adverse effects. High occupational exposure can be found among agricultural workers or during manufacturing of ethylenbisdithiocarbamates (EBDC). For the general public, sources of environmental exposure may be residues of ETU in commercial products, food and beverages. For the determination of ETU in human urine we present a high-throughput online on-column extraction liquid chromatography triple quadrupole mass spectrometry method using direct injection of hydrolysed urine samples. This method is simple, user- and environmentally friendly and all sample preparation is performed in 96-well plates. A labelled ETU internal standard was used for quantification. The method showed a good sensitivity with a limit of quantification (LOQ) of 0.5ng ETU/mL urine and the calibration curve was linear in the range 0.25-200ng ETU/mL urine. The within-run, between-run and between-batch precision was between 6% and 13%. Alkaline hydrolysis considerably increased the levels of ETU indicating a potential conjugate. The method was applied in an experimental dermal exposure study in humans, with sample concentrations ranging from 0.4 to 5.0ng ETU/mL urine. The excretion in urine was 10% of the applied dose. The elimination profile seemed to differ between the two individuals. The results show an estimated half-life of ETU between 34 and 72h. Although the experiment is limited to two individuals, the data provide valuable and new information regarding the toxicokinetics of ETU after dermal exposure.
15.	El-Serafi, I, et al. (författare) Gas chromatographic-mass spectrometry method for the detection of busulphan and its metabolites in plasma and urine 2013 Ingår i: Journal of chromatography. B, Analytical technologies in the biomedical and life sciences. - : Elsevier BV. - 1873-376X. ; 913913-914, s. 98-105 Tidskriftsartikel (refereegranskat)
16.	Ghaffarzadegan, Tannaz, et al. (författare) Determination of bile acids by hollow fibre liquid-phase microextraction coupled with gas chromatography. 2014 Ingår i: Journal of Chromatography. B. - : Elsevier BV. - 1873-376X .- 1570-0232. ; 944, s. 69-74 Tidskriftsartikel (refereegranskat)abstract A method based on hollow-fibre liquid phase microextraction combined with gas chromatography was developed for determination of specific bile acids in caecal materials of rats. Nine unconjugated bile acids, including the primary bile acids (cholic acid, chenodeoxycholic acid and α-muricholic acid) and the secondary bile acids (lithocholic acid, deoxycholic acid, ursodeoxycholic acid, hyodeoxycholic acid, β-muricholic acid and ω-muricholic acid) were quantified. Extraction conditions were evaluated, including: sample pH, type of organic solvent and amount of caecal material to be extracted. To compensate for sample matrix effects during extraction the method of standard addition was applied. The satisfactory linearity (r(2)>0.9840), high recovery (84.2-108.7%) and good intra-assay (6.3-10.6%) and inter-assay (6.9-11.1%) precision illustrated the good performance of the present method. The method is rapid, simple and capable of detecting and determining bile acids with limit of detection (LOD) ranged from 0.002 to 0.067μg/mL and limits of quantification (LOQ) varied from 0.006 to 0.224μg/mL. The results indicated that the concentration of some secondary bile acids, which usually are associated with health problems, were lower in rats fed with fermentable dietary fibre compared with a fibre free control diet, while the concentration of primary bile acids, usually connected with positive health effects, were higher in rats fed with diets containing dietary fibre. Of the dietary fibres, guar gum and to some extent the mixture of pectin+guar gum had the most positive effects. Thus, it was concluded that the composition of bile acids can be affected by the type of diet.
17.	Hakkinen, MR, et al. (författare) Analysis of free, mono- and diacetylated polyamines from human urine by LC-MS/MS 2013 Ingår i: Journal of chromatography. B, Analytical technologies in the biomedical and life sciences. - : Elsevier BV. - 1873-376X. ; 941, s. 81-89 Tidskriftsartikel (refereegranskat)
18.	Jacksén, Johan, et al. (författare) Capillary electrophoresis separation and matrix-assisted laser desorption/ionization mass spectrometry characterization of bovine serum albumin fluorescein isothiocyanate conjugates 2010 Ingår i: Journal of chromatography. B. - : Elsevier BV. - 1570-0232 .- 1873-376X. ; 878:15-16, s. 1125-1134 Tidskriftsartikel (refereegranskat)abstract 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.
19.	Javanbakht, Mehran, et al. (författare) On-line clean-up and determination of tramadol in human plasma and urine samples using molecularly imprinted monolithic column coupling with HPLC 2012 Ingår i: Journal of chromatography. B. - : Elsevier BV. - 1570-0232 .- 1873-376X. ; 911:12, s. 49-54 Tidskriftsartikel (refereegranskat)abstract The applicability of an on-line solid phase extraction method using molecularly imprinted monolithic column was developed for the assay of tramadol (TRD) in urine and plasma samples. The monolithic column was prepared by using TRD as the template, methacrylic acid (MAA) as the functional monomer, ethylene glycol dimethacrylate (EGDMA) as the cross-linker and chloroform as the porogen with in situ molecular imprinting polymerization technique. Various parameters affecting the extraction efficiency of the monolithic column were evaluated. Chromatographic analysis of TRD after on-line clean-up of samples was performed by reversed-phase HPLC on an ACE column with ultraviolet detection at 218 nm. The present work was successfully applied for automated simple analysis of TRD in urine and plasma samples with high recoveries between 90.5–93.1% and 93.3–96.0%, respectively. The results revealed that in concentration up to 500 ng/mL of dextromethorphan (DEX), timolol (TMO) and O-desmethyltramadol (M1), the recoveries were not reduced more than 4.3% and 4.0% for plasma and urine samples, respectively. The limit of detection (S/N = 3) and limit of quantification (S/N = 10) for TRD in urine samples were 0.03 ng/mL and 0.10 ng/mL, and in plasma samples were 0.3 and 1.0 ng/mL, respectively. Inter-column precision of the assays (n = 3) for urine and plasma samples at the 100 ng/mL TRD level were 4.0% and 4.2%, respectively.
20.	Jeppsson, Marina, et al. (författare) Identification of covalent binding sites of ethyl 2-cyanoacrylate, methyl methacrylate and 2-hydroxyethyl methacrylate in human hemoglobin using LC/MS/MS techniques. 2010 Ingår i: Journal of Chromatography. B. - : Elsevier BV. - 1873-376X .- 1570-0232. ; 878, s. 2474-2482 Tidskriftsartikel (refereegranskat)abstract Acrylates are used in vast quantities, for instance in paints, adhesive glues, molding. They are potent contact allergens and known to cause respiratory hypersensitivity and asthma. Here we study ethyl 2-cyanoacrylate (ECA), methyl methacrylate (MMA) and 2-hydroxyethyl methacrylate (HEMA). There are only limited possibilities to measure the exposure to acrylates, especially for biological monitoring. The aim of the present study was to investigate the chemical structures of adducts formed after reaction of hemoglobin (Hb) with ECA, MMA, and HEMA. This information may be used to identify adducted Hb peptides for biological monitoring of exposure to acrylates. Hb-conjugates with ECA, MMA, and HEMA were synthesized in vitro. The conjugates were digested by trypsin and pronase E. Adducted peptides were characterized and analyzed by liquid chromatography and nano electro spray/hybrid quadrupole time-of-flight mass spectrometry (MS) as well as tandem quadrupole MS. The search for the adducted peptides was facilitated by visualizing the MS data by different computer programs. The results showed that ECA binds covalently to cysteines at the 104 position in the alpha and the position 112 in the beta-chains in Hb. MMA and HEMA bound to all the cysteines in both chains, Cys(104) in the alpha-chain and Cys(93) and 112 in the beta-chain. The full-length spectra of in un-digested Hb confirmed this binding pattern. There was no reaction with N-acetyl-l-lysine at physiological pH. The adducted peptides were possible to measure using LC/MS/MS in selected reaction monitoring mode. These peptides may be used for biological monitoring of exposure to ECA, MMA and HEMA.
21.	Karim, Hazhar, et al. (författare) Comparison of three methods for measuring thiopurine methyltransferase activity in red blood cells and human leukemia cells 2013 Ingår i: Journal of chromatography. B. - : Elsevier. - 1570-0232 .- 1873-376X. ; 939, s. 80-85 Tidskriftsartikel (refereegranskat)abstract 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.
22.	Kouremenos, Konstantinos A., et al. (författare) Liquid chromatography time of flight mass spectrometry based environmental metabolomics for the analysis of Pseudomonas putida Bacteria in potable water 2014 Ingår i: Journal of chromatography. B. - : Elsevier BV. - 1570-0232 .- 1873-376X. ; 966, s. 179-186 Tidskriftsartikel (refereegranskat)abstract Water supply biofilms have the potential to harbour waterborne diseases, accelerate corrosion, and contribute to the formation of tuberculation in metallic pipes. One particular species of bacteria known to be found in the water supply networks is Pseudomonas sp., with the presence of Pseudomonas putida being isolated to iron pipe tubercles. Current methods for detecting and analysis pipe biofilms are time consuming and expensive. The application of metabolomics techniques could provide an alternative method for assessing biofilm risk more efficiently based on bacterial activity. As such, this paper investigates the application of metabolomic techniques and provides a proof-of-concept application using liquid chromatography coupled with time-of-flight mass spectrometry (LC-ToF-MS) to three biologically independent P. putida samples, across five different growth conditions exposed to solid and soluble iron (Fe). Analysis of the samples in +ESI and -ESI mode yielded 887 and 1789 metabolite features, respectively. Chemometric analysis of the +ESI and -ESI data identified 34 and 39 significant metabolite features, respectively, where features were considered significant if the fold change was greater than 2 and obtained a p-value less than 0.05. Metabolite features were subsequently identified according to the Metabolomics Standard Initiative (MSI) Chemical Analysis Workgroup using analytical standards and standard online LC-MS databases. Possible markers for P. putida growth, with and without being exposed to solid and soluble Fe, were identified from a diverse range of different chemical classes of metabolites including nucleobases, nucleosides, dipeptides, tripeptides, amino acids, fatty acids, sugars, and phospholipids.
23.	Lindh, Christian, et al. (författare) Analysis of chlormequat in human urine as a biomarker of exposure using liquid chromatography triple quadrupole mass spectrometry. 2011 Ingår i: Journal of Chromatography. B. - : Elsevier BV. - 1873-376X .- 1570-0232. ; 879:19, s. 1551-1556 Tidskriftsartikel (refereegranskat)abstract In this study, a method using liquid chromatography triple quadrupole mass spectrometry (LC/MS/MS) is described for the analysis of the plant growth regulator chlormequat (CCC) in human urine. Analysis was carried out using selected reaction monitoring (SRM) in the positive ion mode. [(2)H(4)] labeled CCC as internal standard (IS) was used for quantification of CCC. The limit of detection (LOD) was determined to 0.1ng/mL. The method was linear in the range 0.3-800ng/mL urine and had a within-run precision of 4-9%. The between-run precision was determined at urine levels of 7.0 and 31ng/mL and found to be 5 and 6% respectively. The reproducibility was 3-6%. To validate CCC as a biomarker of exposure, the method was applied in a human experimental oral exposure to CCC. Two healthy volunteers received 25μg/kg b.w. CCC in a single oral dose followed by urine sampling for 46h post-exposure. The CCC was estimated to follow a first order kinetic and a two compartment model with an elimination half-life of 2-3h and 10-14h respectively. One hundred 24h urine samples were collected from non-occupationally exposed individuals in the general population in southern Sweden. All samples had detectable levels above the LOD 0.1ng/mL urine. The median levels were 4ng/mL of CCC in unadjusted urine. The levels found in the population samples are several magnitudes lower than those found in the experimental exposure, which corresponds to an oral exposure of 50% of the ADI for CCC.
24.	Lindqvist, Annika, et al. (författare) Quantitative analysis of the opioid peptide DAMGO in rat plasma and microdialysis samples using liquid chromatography-tandem mass spectrometry 2012 Ingår i: Journal of chromatography. B. - : Elsevier BV. - 1570-0232 .- 1873-376X. ; 900, s. 11-17 Tidskriftsartikel (refereegranskat)abstract A liquid chromatography–electrospray ionization-tandem mass spectrometry (LC–ESI-MS/MS) method for the quantification of the opioid peptide DAMGO in rat plasma, as well as DAMGO and the microdialysis recovery calibrator [13C2,15N]-DAMGO in microdialysis samples, is described. The microdialysis samples consisted of 15 μL Ringer solution containing 0.5% bovine serum albumin. Pretreatment of the samples involved protein precipitation with acetonitrile followed by dilution with 0.01% formic acid. The lower limits of quantification were 0.52 ng/mL and 0.24 ng/mL for DAMGO and [13C2,15N]-DAMGO respectively and the response was linear up to 5000 fold higher concentrations. The plasma samples (50 μL) were precipitated with acetonitrile containing the isotope labeled analog [13C2,15N]-DAMGO as internal standard. The method was linear in the range of 11–110,000 ng/mL. The separations were conducted on a HyPurity C18 column, 50 × 4.6 mm, 3 μm particle size, with a mobile phase consisting of acetonitrile, water and formic acid to the proportions of 17.5:82.5:0.01. Low energy collision dissociation tandem mass spectrometric (CID-MS/MS) analysis was carried out in the positive ion mode using multiple reaction monitoring (MRM) of the following mass transitions: m/z 514.2 → 453.2 for DAMGO and m/z 517.2 → 456.2 for [13C2,15N]-DAMGO. The intra-day precision and accuracy did not exceed 5.2% and 93–104% for both compounds and sample types described. The inter-day precision an accuracy were <6.8% and 95–105% respectively. The method described is simple, reproducible and suitable for the analysis of small sample volumes at low concentrations.
25.	Magiera, Sylwia, et al. (författare) A liquid chromatography and tandem mass spectrometry method for the determination of potential biomarkers of cardiovascular disease 2013 Ingår i: Journal of chromatography. B. - : Elsevier. - 1570-0232 .- 1873-376X. ; 919, s. 20-29 Tidskriftsartikel (refereegranskat)abstract 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.
26.	Magiera, Sylwia, et al. (författare) Comparison of different sorbent materials for solid-phase extraction of selected drugs in human urine analyzed by UHPLC-UV 2014 Ingår i: Journal of chromatography. B. - : Elsevier. - 1570-0232 .- 1873-376X. ; 958, s. 22-28 Tidskriftsartikel (refereegranskat)abstract 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.
27.	Marklund, Matti, et al. (författare) Comparison of gas chromatography-mass spectrometry and high-performance liquid chromatography with coulometric electrode array detection for determination of alkylresorcinol metabolites in human urine 2011 Ingår i: Journal of Chromatography B. - : Elsevier BV. - 1570-0232 .- 1873-376X. ; 879, s. 647-651 Tidskriftsartikel (refereegranskat)abstract Alkylresorcinols (AR) are amphiphilic compounds present at high concentrations in the outer parts of wheat and rye kernels. Due to their specificity to whole grain and bran products of these cereals, AR and their metabolites have been proposed as biomarkers for intake of such foods. Two alkylresorcinol metabolites, 3,5-dihydroxybenzoic acid (DHBA) and 3-(3,5-dihydroxyphenyl)-1-propanoic acid (DHPPA), have previously been quantified in human urine using two different methodologies: high-performance liquid chromatography coupled to a coulometric electrode array detector (HPLC-CEAD) and gas chromatography in combination with mass spectrometry (GC-MS). In this study, these two methodologies were compared by analysing 114 urine samples from free-living Swedish subjects consuming their habitual diet. Data were evaluated by graphical investigation of difference-plots and statistical inference of agreement was assessed by weighted Deming regression analysis. The median DHBA concentrations were 11 mu M (GC-MS) and 13 mu M (HPLC-CEAD), respectively. Both difference-plot and regression analysis showed a small but statistically significant additive bias, with HPLC-CEAD resulting in a slightly higher DHBA concentration than GC-MS. The median concentration of DHPPA was 18 mu M for both methods. Examination of the difference-plot of DHPPA did not indicate any systematic difference between the methods, but regression analysis showed small but statistically significant constant and proportional biases. The conclusion was that the two methodologies are equally suitable for analysis of alkylresorcinol metabolites in human urine and that any small systematic differences observed are most likely of limited practical importance. (C) 2011 Elsevier B.A. All rights reserved.
28.	Marklund, Matti, et al. (författare) Determination of alkylresorcinol metabolites in human urine by gas chromatography-mass spectrometry 2010 Ingår i: Journal of Chromatography B. - : Elsevier BV. - 1570-0232 .- 1873-376X. ; 878, s. 888-894 Tidskriftsartikel (refereegranskat)abstract Alkylresorcinols (ARs) are phenolic lipids present at high concentrations in the outer parts of rye and wheat kernels and have been proposed as biomarkers for intake of whole grain and bran products of these cereals. AR are absorbed in the small intestine and after hepatic metabolism two major metabolites, 3,5-dihydroxybenzoic acid (DHBA) and 3-(3,5-dihydroxyphenyl)-1-propanoic acid (DHPPA), are excreted in urine either as such or as conjugates. Urine samples from nine individuals were incubated with different enzymes to assess type and extent of conjugates. In comparison with DHBA, which was mostly found in the free form, the less polar DHPPA was conjugated to a greater extent and the major conjugates were glucuronides. In this method, urine samples were hydrolyzed using beta-glucuronidase from Helix pomatia and syringic acid was used as internal standard. Samples, silylated with BSTFA, were analyzed by GC-MS utilizing a BP-5 fused silica capillary column and single ion monitoring of molecular ions (m/z 370 [DHBA], m/z 398 [DHPPA]). Recoveries of DHBA and DHPPA were estimated to be 94% and 93%, respectively. The average intra-assay/inter-assay coefficients of variation were 4.9/5.7% for DHBA and 7.6/9.3% for DHPPA. (c) 2010 Elsevier B.V. All rights reserved.
29.	Moein, Mohammad Mahdi, 1985-, et al. (författare) Molecularly imprinted polymer cartridges coupled on-line with high performance liquid cheomatography for simple and rapid analysis of dextromethorphan in human plasma samples 2011 Ingår i: Journal of chromatography. B. - : Elsevier BV. - 1570-0232 .- 1873-376X. ; 879:11-12, s. 777-782 Tidskriftsartikel (refereegranskat)abstract In this paper, a novel method is described for automated determination of dextromethorphan in biological fluids using molecularly imprinted solid-phase extraction (MISPE) as a sample clean-up technique combined with high performance liquid chromatography (HPLC). The water-compatible molecularly imprinted polymers (MIPs) were prepared using methacrylic acid as functional monomer, ethylene glycol dimethacrylate as cross-linker, chloroform as porogen and dextromethorphan as template molecule. These imprinted polymers were used as solid-phase extraction sorbent for the extraction of dextromethorphan from human plasma samples. Various parameters affecting the extraction efficiency of the MIP cartridges were evaluated. The high selectivity of the sorbent coupled to the high performance liquid chromatographic system permitted a simple and rapid analysis of this drug in plasma samples with limits of detection (LOD) and quantification (LOQ) of 0.12 ng/mL and 0.35 ng/mL, respectively. The MIP selectivity was evaluated by analyzing of the dextromethorphan in presence of several substances with similar molecular structures and properties. Results from the HPLC analyses showed that the recoveries of dextromethorphan using MIP cartridges from human plasma samples in the range of 1–50 ng/mL were higher than 87%.
30.	Moein, Mohammad Mahdi, et al. (författare) Preparation of monolithic molecularly imprinted polymer sol-gel packed tips for high-throughput bioanalysis : Extraction and quantification of L-tyrosine in human plasma and urine samples utilizing liquid chromatography and tandem mass spectrometry 2014 Ingår i: Journal of chromatography. B. - : Elsevier BV. - 1570-0232 .- 1873-376X. ; 967, s. 168-173 Tidskriftsartikel (refereegranskat)abstract In situ monolithic molecularly imprinted polymer sol-gel packed tips (MMSTs) were prepared and evaluated for the extraction of lung cancer biomarker L-tyrosine (Tyr) from human plasma and urine samples. Several extraction parameters such as the conditioning, washing and elution solutions, pH and time were investigated. The enrichment factor (EF) and extraction recovery (ER) were studied. MMST showed good selectivity and a high extraction recovery, and MMST as a sorbent showed good stability and repeatability. The method validation showed good regression correlation coefficients for plasma and urine samples (R-2 >= 0.996) within the concentration range of 5-1000 and 1-1000 nmol L-1 in plasma and urine samples, respectively. The lower limits of quantification (LLOQ) in the plasma and urine samples were 5 and 1 nmol L-1, respectively. The between-batch precision for Tyr in plasma ranged from 1.0 to 6.0%, and in urine it was from 1.0 to 7.0%. The results show that the developed method has more facility, stability, durability and repeatability compared with previous similar methods. To the best of our knowledge, this is the first study aimed at the selective separation of Tyr as a lung cancer biomarker by MMSTs from biological matrixes and detection by LC/MS/MS.
31.	Möller, Kristina, et al. (författare) Evaluation of molecularly imprinted solid-phase extraction for a 1,2:3,4-diepoxybutane adduct to valine in haemoglobin 2010 Ingår i: Journal of chromatography. B. - : Elsevier BV. - 1570-0232 .- 1873-376X. ; 878:27, s. 2497-2501 Tidskriftsartikel (refereegranskat)abstract A molecularly imprinted polymer, MIP, was prepared and evaluated as SPE sorbent for a cyclicized adduct formed to N-terminal valine (Pyr-Val) in hemoglobin from 1,2:3,4-diepoxybutane (DEB). This metabolite plays an important role in the carcinogenesis of 1,3-butadiene. The hydrazide of Pyr-Val, formed after hydrazinolysis of hemoglobin, as well as necessary standards was synthesized. The MIP was prepared from methacrylic acid with a structure analogue to the investigated adduct as template and the method was developed for aqueous conditions. Selective desorption was achieved when the sample was washed with water after loading in 10% acetonitrile. The primary interaction with the binding sites in the imprints was most likely of ionic character. Quantification of the Pyr-Val adduct was performed with LC/ESI-MS/MS, yielding an instrumental LOD of 150 pg injected amount.
32.	Nakao, R, et al. (författare) Rapid and sensitive measurement of PET radioligands in plasma by fast liquid chromatography/radiometric detection 2012 Ingår i: Journal of chromatography. B, Analytical technologies in the biomedical and life sciences. - : Elsevier BV. - 1873-376X. ; 895895-896, s. 116-122 Tidskriftsartikel (refereegranskat)
33.	Nilsson, K, et al. (författare) Phospholipid removal combined with a semi-automated 96-well SPE application for determination of budesonide in human plasma with LC-MS/MS 2014 Ingår i: Journal of chromatography. B, Analytical technologies in the biomedical and life sciences. - : Elsevier BV. - 1873-376X. ; 970, s. 31-35 Tidskriftsartikel (refereegranskat)
34.	O'Mahony, John, et al. (författare) Design and implementation of an imprinted material for the exaction of the endocrine disruptor bisphenol A from milk 2013 Ingår i: Journal of chromatography. B. - : Elsevier BV. - 1570-0232 .- 1873-376X. ; 931, s. 164-169 Tidskriftsartikel (refereegranskat)abstract This paper describes the determination of bisphenol A (BPA) in milk samples, using a novel molecularly imprinted polymer. The imprinted polymer was developed using a rational design approach, and pre-polymerization interactions were investigated using molecular dynamics simulations and X-ray crystallography. A hydroquinone-imprinted polymer was used for solid phase extraction (SPE) clean-up of samples. BPA was quantified by high performance liquid chromatography (HPLC) and fluorescence (FLD) detection. Following validation, the method described was capable of determining bisphenol A in milk down to a limit of detection of 1.32 mu g kg(-1). The method was applied to a survey (n = 27) of commercial milk products; BPA was detected in one of the samples, at a level of 176 mu g kg(-1). Test results were confirmed by a parallel UHPLC-MS/MS analytical method. This demonstrates the utility of the hydroquinone-imprinted polymer for application to selective sample clean-up and analysis of bisphenol A in milk, avoiding possible detrimental affects associated with template bleeding and without the need for expensive or difficult-to-obtain template. (C) 2013 Elsevier B.V. All rights reserved.
35.	Ronquist-Nii, Yuko, et al. (författare) Determination of picropodophyllin and its isomer podophyllotoxin in human serum samples with electrospray ionization of hexylamine adducts by liquid chromatography-tandem mass spectrometry 2011 Ingår i: Journal of chromatography. B. - : Elsevier BV. - 1570-0232 .- 1873-376X. ; 879:5-6, s. 326-334 Tidskriftsartikel (refereegranskat)abstract A liquid chromatography-tandem mass spectrometry (LC-MS/MS) method for determination of the new anticancer agent picropodophyllin (AXL1717) and its isomer podophyllotoxin levels in human serum has been developed. Monitoring of hexylamine adducts rather than proton adducts was used to optimize sensitivity. The chromatography system was an Acquity BEN C18, 2.1 mm x 50 mm 1.7 mu m column with gradient elution (mobile phase A: 2.5 mM hexylamine and 5 mM formic acid in Milli-Qwater and mobile phase B: methanol). The retention times were 1.4 min for picropodophyllin, 1.5 min for podophyllotoxin and 1.9 min for internal standard deoxypodophyllotoxin. The isomers were base-line separated. The analytes were detected after electrospray ionization in positive mode with selected reaction monitoring (SRM) with ion transitions m/z 516 --> 102 for picropodophyllin and podophyllotoxin and m/z 500 --> 102 for internal standard. The sample preparation was protein precipitation with acetonitrile (1:3) containing internal standard followed by dilution of the supernatant with mobile phase A (1:1). The limit of quantification (LOQ) was 0.01 mu mol/L for picropodophyllin and podophyllotoxin. The limit of detection (LOD) at 3 times the signal to noise (S/N) was estimated below 0.001 mu mol/L for picropodophyllin and podophyllotoxin. The quantification range of the method was between 0.01 mu mol/L and 5 mu mol/L for both isomers. The accuracy was within +/-15% of the theoretical value for both picropodophyllin and podophyllotoxin and inter-assay precision did not exceed +/-15%, except for the 0.016 mu mol/L level of podophyllotoxin, which was 18%. The selectivity of the method was verified by analysis of two different product ions for each analyte and by analysis for interference of seven different batches of blank human serum. The combined recovery and matrix effects were about 83% for picropodophyllin and podophyllotoxin. The new LC-MS/MS method showed sufficient sensitivity and selectivity for determination of picropodophyllin and its isomer podophyllotoxin levels in human serum from subjects receiving therapeutic doses of AXL1717.
36.	Said, Rana, et al. (författare) Determination of four immunosuppressive drugs in whole blood using meps and lc ms/ms allowing automated sample work up and analysis 2012 Ingår i: Journal of chromatography. B. - : Elsevier BV. - 1570-0232 .- 1873-376X. ; 897, s. 42-49 Tidskriftsartikel (refereegranskat)abstract In treatment with immunosuppressive drugs, monitoring of blood drug concentration is needed. The aim of this work was to explore micro extraction by packed sorbent (MEPS) as a possible on-line sample preparation method in combination with liquid chromatography-tandem mass spectrometry (LC-MS/MS) for quantification of cyclosporine, everolimus, sirolimus and tacrolimus in whole blood. An automated on-line MEPS system connected with a LC-MS/MS instrument was set up. A C-8 sorbent was used for the MEPS extraction. Subsequent analysis was performed with a gradient LC system. The adduct ions [M + NH4](+) of the analytes were monitored in SRM mode for quantification. Ascomycin and cyclosporine D were used as internal standards. The chromatographic run time 2.5 min and the quantification ranges were 3-1500 ng/mL (r(2) >= 0.999, n = 6) for cyclosporine and 0.5-50 ng/mL for everolimus, sirolimus and tacrolimus (r(2) >= 0.998. 0.994 and 0.993, respectively, n = 6). Precision and accuracy were documented at three levels. Accuracy results were between 102% and 109% with precision between 2% and 13% and carry over < 0.02%. Matrix effects were characterized and found to be below 20%. The quantifications obtained were in agreement with a reference LC-MS/MS method based on protein precipitation, and results obtained from external proficiency test samples compared with the mean of all other LC-mass spectrometry methods showed good agreement. This method provides an accurate, precise and automated procedure that can be applied for therapeutic drug monitoring of immunosuppressive drugs in clinical laboratories equipped with LC-MS/MS.
37.	Said, R, et al. (författare) Determination of remifentanil in human plasma by liquid chromatography-tandem mass spectrometry utilizing micro extraction in packed syringe (MEPS) as sample preparation 2011 Ingår i: Journal of chromatography. B, Analytical technologies in the biomedical and life sciences. - : Elsevier BV. - 1873-376X. ; 879:11-12, s. 815-818 Tidskriftsartikel (refereegranskat)
38.	Saleh, Aljona, et al. (författare) Evaluation of a direct high-capacity target screening approach for urine drug testing using liquid chromatography-time-of-flight mass spectrometry 2012 Ingår i: Journal of chromatography. B. - : Elsevier BV. - 1570-0232 .- 1873-376X. ; :909, s. 6-13 Tidskriftsartikel (refereegranskat)abstract In this study a rapid liquid chromatography-time-of-flight mass spectrometry method was developed, validated and applied in order to evaluate the potential of this technique for routine urine drug testing. Approximately 800 authentic patient samples were analyzed for amphetamines (amphetamine and methamphetamine), opiates (morphine, morphine-3-glucuronide, morphine-6-glucuronide, codeine and codeine-6-glucuronide) and buprenorphines (buprenorphine and buprenorphine-glucuronide) using immunochemical screening assays and mass spectrometry confirmation methods for comparison. The chromatographic application utilized a rapid gradient with high flow and a reversed phase column with 1.8 mu m particles. Total analysis time was 4 min. The mass spectrometer operated with an electrospray interface in positive mode with a resolution power of >10,000 at m/z 956. The applied reporting limits were 100 ng/mL for amphetamines and opiates, and 5 ng/mL for buprenorphines, with lower limits of quantification were 2.8-41 ng/mL. Calibration curves showed a linear response with coefficients of correlation of 0.97-0.99. The intra- and interday imprecision in quantification at the reporting limits were <10% for all analytes but for buprenorphines <20%. Method validation data met performance criteria for a qualitative and quantitative method. The liquid chromatography-time-of-flight mass spectrometry method was found to be more selective than the immunochemical method by producing lower rates of false positives (0% for amphetamines and opiates; 3.2% for buprenorphines) and negatives (1.8% for amphetamines; 0.6% for opiates; 0% for buprenorphines). The overall agreement between the two screening methods was between 94.2 and 97.4%. Comparison of data with the confirmation (LC-MS) results for all individual 9 analytes showed that most deviating results were produced in samples with low levels of analytes. False negatives were mainly related to failure of detected peak to meet mass accuracy criteria (+/- 20 mDa). False positives was related to presence of interfering peaks meeting mass accuracy and retention time criteria and occurred mainly at low levels. It is concluded that liquid chromatography-time-of-flight mass spectrometry has potential both as a complement and as replacement of immunochemical screening assays.
39.	Sjödin, Marcus O.D. 1978-, et al. (författare) Comparative study of label and label-free techniques using shotgun proteomics for relative protein quantification 2013 Ingår i: Journal of chromatography. B. - : Elsevier BV. - 1570-0232 .- 1873-376X. ; 928, s. 83-92 Tidskriftsartikel (refereegranskat)abstract The analytical performance of three different strategies, iTRAQ (isobaric tag for relative and absolute quantitation), dimethyl labeling (DML) and label free (LF) for relative protein quantification using shotgun proteomics have been evaluated. The methods have been explored using samples containing (i) Bovine proteins in known ratios and (ii) Bovine proteins in known ratios spiked into E.Coli. The latter case mimics the actual conditions in a typical biological sample with a few differentially expressed proteins and a bulk of proteins with unchanged ratios. Additionally, the evaluation was performed on both Q-TOF and LTQ-FTICR mass spectrometers. LF LTQ-FTICR was found to have the highest proteome coverage (94 %) while the highest accuracy based on the artificially regulated proteins was found for DML LTQ-FTICR (54%). A good linearity (r2: 0.61-0.96) was shown for all methods within selected dynamic ranges. All methods were found to consistently underestimate bovine protein ratios when matrix proteins were added. However LF LTQ-FTICR was more tolerant towards a compression effect. A single peptide was demonstrated to be sufficient for a reliable quantification using iTRAQ. A ranking system utilizing several parameters important for quantitative proteomics demonstrated that the overall performance of the five different methods were; DML LTQ-FTICR > iTRAQ QTOF > LF LTQ-FTICR > DML Q-TOF > LF Q-TOF.
40.	Sjödin, Marcus O.D., et al. (författare) Mining ventricular cerebrospinal fluid from patients with traumatic brain injury using hexapeptide ligand libraries to search for trauma biomarkers 2010 Ingår i: Journal of chromatography. B. - : Elsevier. - 1570-0232 .- 1873-376X. ; 878:22, s. 2003-2012 Tidskriftsartikel (refereegranskat)abstract Traumatic brain injury (TBI) is an acute event resulting from external force to the brain and is a major cause of death and disability associated with high health care costs in the western world. Additional injuries, originating from the secondary molecular events after the initial intensive care, may be limited by the use of objective biomarkers to provide the best treatment and patient prediction outcome. In this study, hexapeptide ligand libraries (HLL) have been used for the enrichment of suggested protein biomarkers for TBI in cerebrospinal fluid (CSF). HLL have the potential to enrich low abundant proteins and simultaneously reduce the high abundant proteins, rendering a sample with significantly reduced dynamic range. The CSF proteome from two TBI inflicted patients have been extensively mapped using a large initial sample volume obtained by extraventricular drainage. Shotgun proteomics, in combination with isoelectric focusing (IEF) and nano-LC-MS/MS, identified 339 unique proteins (MudPIT scoring p ≤ 0.05) with a protein overlap of 130 between the patients. As much as 45% of the proteins reported in the literature to be associated with degenerative/regenerative processes occurring after a trauma to the head were identified. Out of the most prominent potential protein biomarkers, such as neuron specific enolase, glial fibrillary acidic protein, myelin basic protein, creatine kinase B-type and S-100β, all except myelin basic protein were detected in the study. This study shows the possibility of using HLL as a tool for screening of low abundant protein biomarkers in human CSF.
41.	Subramaniam, Raja, et al. (författare) Direct derivatization and gas chromatography-tandem mass spectrometry identification of nerve agent biomarkers in urine samples 2013 Ingår i: Journal of chromatography. B. - : Elsevier. - 1570-0232 .- 1873-376X. ; 928, s. 98-105 Tidskriftsartikel (refereegranskat)abstract Rapid determination of nerve agent biomarkers at low-ppb levels in urine samples was achieved by direct derivatization and sample analysis using gas chromatography-tandem mass spectrometry. The studied biomarkers were alkylphosphonic acids (APAs), as they are specific hydrolysis products of organophosphorus nerve agents that can be used to verify nerve agent exposure. The sample preparation technique employed involves rapid direct derivatization (5min) of acidified urine samples (25μL) using a highly fluorinated phenyldiazomethane reagent [1-(diazomethyl)-3,5-bis(trifluoromethyl)benzene]. The derivatization conditions were optimized using statistical experimental design and multivariate data analysis. The APA derivatives were analyzed by GC-MS and MS/MS using negative ion chemical ionization. The selectivity and sensitivity of analyses performed by low and high resolution single ion monitoring MS-mode were compared with those performed by multiple reaction monitoring MS/MS-mode. The MS/MS technique offered the greatest sensitivity and selectivity of the tested mass spectrometric techniques, with limits of detection ranging from 0.5 to 1ng APAs/mL of urine. The method's robustness was evaluated using urine samples from the OPCW 2nd biomedical confidence building exercise and all APAs present in the samples were conclusively identified. The method thus offers excellent performance and is viable for the simultaneous trace determination of a wide range of nerve agent markers.
42.	Svensson, David, et al. (författare) Characterisation of a glycosylated alkyl polyglycoside produced by a cyclodextrin glycosyltransferase by HPLC-ELSD and -MS. 2011 Ingår i: Journal of Chromatography. B. - : Elsevier BV. - 1873-376X .- 1570-0232. ; 879, s. 1857-1860 Tidskriftsartikel (refereegranskat)abstract A transglycosylation reaction between an alkyl polyglycoside and α-cyclodextrin catalysed by cyclodextrin glycosyltransferase (CGTase) from Bacillus macerans was investigated. The reaction products were identified by comparison with standards generated by CGTase catalysed modification of pure alkyl glycosides using HPLC-ELSD and -MS analysis. The main products were alkyl glucopyranosides (substrates present in the alkyl polyglycoside) glycosylated with 6 (primary coupling products) or 12 (secondary coupling products) glucose residues. Both α and β anomers were glycosylated.
43.	Thuy, Tran Thi, et al. (författare) Parallel sample preparation of proteins, from crude samples to crystals ready for MALDI-MS, in an integrated microfluidic system 2010 Ingår i: Journal of chromatography. B. - : Elsevier BV. - 1570-0232 .- 1873-376X. ; 878:28, s. 2803-2810 Tidskriftsartikel (refereegranskat)abstract A microfluidic structure is presented where selective capture of proteins in complex samples, followed by clean-up, enzymatic processing, and MALDI-MS sample preparation of peptides generated, can be performed. The structure uses an affinity column to capture the protein while all other components in the sample are disposed of. The protein of interest is then eluted from the affinity column and captured on a second column on which the enzymatic processing is performed. Salts and hydrophilic contaminants are then removed before the products from the enzymatic reaction are eluted together with a suitable MALDI matrix and the solvent evaporated in a designated MALDI target structure. All steps can be performed automatically in 54 parallel microstructures on a microfluidic compact disc. The process is demonstrated by the selective capture and tryptic digest of recombinant IgG molecules from samples containing other proteins: an excess of bovine serum albumin or spent cell culture media.
44.	van de Merbel, Nico C, et al. (författare) Quantitative determination of the anti-tumor agent tasquinimod in human urine by liquid chromatography-tandem mass spectrometry. 2014 Ingår i: Journal of Chromatography. B. - : Elsevier BV. - 1873-376X .- 1570-0232. ; 961:May 14, s. 42-48 Tidskriftsartikel (refereegranskat)abstract Tasquinimod is an anti-tumor drug that is currently in clinical development for the treatment of solid cancers. After oral administration, tasquinimod and a number of its metabolites are excreted in the urine. The quantitative determination of tasquinimod in urine is challenging because of the required sensitivity (down to 0.1nM or 40pg/mL), the highly variable nature of this biological matrix and the presence of potentially unstable metabolites, which may convert back to the parent drug. In this article, an LC-MS/MS method is described for the determination of tasquinimod in human urine in the concentration range 0.1-200nM. Liquid-liquid extraction with n-chlorobutane was used to extract tasquinimod from 100μL human urine and to remove interfering endogenous urinary constituents. Reversed-phase liquid chromatography coupled to a triple quadrupole mass spectrometer equipped with an ESI source was used for quantification of tasquinimod in a 2.5-min run. A stable-isotope labeled internal standard was used for response normalization. The intra- and inter-day coefficients of variation (precision) as well as the bias (accuracy) of the method were below 7%. Although considerable conversion of conjugated tasquinimod metabolites back to parent drug was observed when incurred samples were stored at 37°C for a prolonged time, tasquinimod as well as its metabolites were sufficiently stable under all relevant sampling, storage and analysis conditions. The method was successfully applied to determine the urinary excretion of tasquinimod in healthy volunteers and patients with renal impairment after a 0.5-mg oral dose.
45.	von Stedingk, Hans, et al. (författare) A new modified Edman procedure for analysis of N-terminal valine adducts in hemoglobin by LC-MS/MS 2010 Ingår i: Journal of chromatography. B. - : Elsevier BV. - 1570-0232 .- 1873-376X. ; 878:27, s. 2483-2490 Tidskriftsartikel (refereegranskat)abstract A rapid and sensitive method using liquid chromatography-tandem mass spectrometry (LC-MS/MS) for simultaneous determination of adducts from acrylamide, glycidamide and ethylene oxide to N-terminal valines in hemoglobin (Hb) was developed. This new procedure is based on the same principles as the N-alkyl Edman procedure for analysis of adducts from electrophilic agents to N-terminal valines in Hb. The N-substituted valines can be detached, enriched and measured selectively as thiohydantoins by the use of an Edman reagent, in this case fluorescein isothiocyanate (FITC). This procedure is denoted as the "adduct FIRE procedure" as the FITC reagent is used for measurement of adducts ((R) under bar) formed from electrophilic compounds with a modified Edman procedure. In this study, fluorescein thiohydantoin (FTH) analytes of N-substituted valines from acrylamicle, glycidamide and ethylene oxide, as well as their corresponding hepta- and tri-deuterium-substituted analogues, were synthesized. These analytes (n = 8) were then characterized by LC-MS/MS (ESI, positive ion mode) and obtained product ions were interpreted. A considerable work with optimization of the FIRE procedure (TM), resulted in a procedure in which low background levels of the studied adducts could be measured from 250 mu L lyzed whole blood samples (human non-smokers). The analytes were enriched and purified with solid phase extraction columns and analyzed by LC-MS/MS with LOQ clown to 1 pmol adduct/g Hb. Compared to other procedures for determination of N-terminal Hb adducts, the introduction of FITC has led to a simplified procedure, where whole blood also can be used, giving new opportunities and reduced hand on time with increased sample throughput.
46.	von Stedingk, Hans, et al. (författare) Methyl vinyl ketone – identification and quantification of adduct to N-terminal valine in human haemoglobin 2010 Ingår i: Journal of chromatography. B. - : Elsevier BV. - 1570-0232 .- 1873-376X. ; 878:27, s. 2491-2496 Tidskriftsartikel (refereegranskat)abstract Adducts to N-terminal valines in Hb have been shown useful as biomarkers of exposure to electrophilic compounds. Adducts from many compounds have earlier been measured with a modified Edman degradation method using a GC–MS/MS method. A recently developed method, the adduct FIRE procedure™, adopted for analysis by LC–MS/MS, has been applied in this study. With this method a fluorescein isothiocyanate (FITC) reagent is used to measure adducts (R) from electrophiles with a modified Edman procedure. By using LC–MS/MS in product ion scan mode, a new peak was identified and the obtained MS data indicated that this adduct could originate from methyl vinyl ketone (MVK). Incubation of human-, sheep- and bovine blood with MVK increased the signal of the identified peak. By comparing the LC–MS/MS data from the unknown background peak with data obtained from synthesized fluorescein thiohydantoin (FTH) standards of the MVK adduct to valine and d8-valine, the identity of this adduct was confirmed. The MVK adduct was shown present in human blood (35 pmol/g globin, n = 3) and only just above LOD in bovine blood, n = 1 (LOD = 2 pmol/g globin). MVK reacts, in similarity with acrylamide, via Michael addition. MVK is known to occur in the environment and has earlier been observed in biological samples, which means that there are possible natural and anthropogenic exposure sources. Analysis of an Hb adduct from MVK in humans has to our knowledge not been described before.
47.	Wetterhall, Magnus, et al. (författare) Assessment of the partitioning capacity of high abundant proteins in human cerebrospinal fluid using affinity and immunoaffinity subtraction spin columns. 2010 Ingår i: Journal of chromatography. B, Analytical technologies in the biomedical and life sciences. - : Elsevier BV. - 1873-376X .- 1570-0232. ; 878:19, s. 1519-30 Tidskriftsartikel (refereegranskat)abstract The performance of three different affinity and immunoaffinity subtraction spin columns was investigated for the removal of the most abundant proteins in human cerebrospinal fluid (CSF). A pool of human CSF was processed with the spin columns and both the bound and flow through fractions were compared with each other and with intact CSF using 1D gel electrophoresis and nanoLC-MALDI-TOF/TOF-MS analysis. MASCOT MS/MS ionscores were compared before and after processing with the columns. The non-specific co-removal of proteins bound to the high abundant proteins, so called "sponge effect" was also examined for each spin column. The reproducibility of one of the spin columns, ProteomeLab IgY-12 proteome partitioning spin column, was further investigated by isobaric tags for relative and absolute quantification (iTRAQ) labeling and MS/MS analysis. Overall, 173 unique proteins were identified on a 95% MudPIT confidence scoring level. For all three spin columns, the number of proteins identified and their MASCOT scores were increased up to 10 times. The largest degree of non-specific protein removal was observed for a purely affinity based albumin removal column, where 28 other proteins also were present. The ProteomeLab IgY-12 proteome partitioning spin column showed very high reproducibility when combined with iTRAQ labeling and MS/MS analysis. The combined relative standard deviation (R.S.D.) for the high abundant protein removal, iTRAQ labeling and nanoLC-MALDI-TOF/TOF-MS analysis was less than 17.5%.
48.	Abdel–Khalik, Jonas, et al. (författare) Development of a solid phase extraction method for the simultaneous determination of steroid hormones in H295R cell line using liquid chromatography–tandem mass spectrometry 2013 Ingår i: Journal of chromatography. B. - : Elsevier BV. - 1570-0232. ; 935:September, s. 61-69 Tidskriftsartikel (refereegranskat)abstract 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.
49.	Abdel–Khalik, Jonas, et al. (författare) Simultaneous determination of endogenous steroid hormones in human and animal plasma and serum by liquid or gas chromatography coupled to tandem mass spectrometry 2013 Ingår i: Journal of chromatography. B. - : Elsevier BV. - 1570-0232. ; 928:June, s. 59-77 Tidskriftsartikel (refereegranskat)abstract 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.
50.	Baranowska, Irena, et al. (författare) UHPLC method for the simultaneous determination of beta-blockers, isoflavones and their metabolites in human urine 2011 Ingår i: JOURNAL OF CHROMATOGRAPHY B-ANALYTICAL TECHNOLOGIES IN THE BIOMEDICAL AND LIFE SCIENCES. - : Elsevier Science B.V., Amsterdam.. - 1570-0232. ; 879:9-10, s. 615-626 Tidskriftsartikel (refereegranskat)abstract A rapid-resolution ultra high-performance liquid chromatography separation method (UHPLC) for the simultaneous determination of the following beta-blockers: milrinone, sotalol, metoprolol, propranolol and carvedilol, and their metabolites: 5-hydroxylphenyl-carvedilol, O-desmethylcarvedilol, 4-hydroxypropranolol, alpha-hydroxy-metoprolol, O-desmethyl-metoprolol; the following isoflavones: genistein, daidzein, glycitin, glycitein, puerarin and biochanin A; as well as their metabolites: dihydrogenistein, desmethylglycitein, 8-hydroxygenistein, daidzein-7,4-diglucoside, 8-hydroxydaidzein, dihydrobiochanin A in human urine was optimized. The analysed compounds were extracted from human urine by means of solid phase extraction (SPE). The effective UHPLC separation of the examined compounds was applied on a Hypersil GOLD (TM) (50 mm x 2.1 mm, 1.9 mu m) column with a gradient mobile phase system and a UV detector. The complete separation of all analytes was achieved within 8.0 min. The method was validated for the determination of the aforementioned substances in human urine. The linear ranges, limits of detection CLOD) and limits of quantification (LOQ) for beta-blockers, isoflavones and their metabolites were determined. The intra- and inter-day precision (%C.V.) was less than 4.48%, and the intra-day and inter-day accuracy was less than 4.74%. The tested SPE sorbent proved that appropriate absolute recoveries can be obtained for Oasis HLB (Waters). The mean recovery of the analytes, using the new SPE procedure, amounted from 70.14% to 99.85%. The present paper reports, for the first time, the method for the determination of beta-blockers, isoflavones and their metabolites in human urine samples. The newly developed method was suitably validated and successfully applied for the analysis of the certain of the aforementioned analytes in human urine samples obtained from the patients suffering cardiovascular disease.

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