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Liquid Chromatography-tandem Mass Spectrometry (liquid + chromatography-tandem_mass_spectrometry)
Selected AbstractsLiquid chromatography-tandem mass spectrometry method for determination of Sirolimus coated drug eluting nano porous carbon stentsBIOMEDICAL CHROMATOGRAPHY, Issue 3 2010G. Rajender Abstract Liquid chromatography-tandem mass spectrometry (LC-MS/MS) method has proved to powerful research tool due to its sensitivity, high selectivity, and high throughput efficiency..Sirolimus was extracted from plasma by two-step extraction procedure using chloroform as extracting solvent. Signal intensity was high using ESI+ source provided for the quantitation of samples. Chromatographic separation was performed on phenomenax C-18 column (250 × 4.60,mm 5microns).Mobile phase contains acetonitrile, water (80; 20 v/v) + 0.1% acetic acid, flow rate 1,mL/min. The retention time of Sirolimus 8.4,min, the total run time10,min. Linearity correlation coefficients (r2) curve was 0.997183.calibraction range 10,1000,ng/mL. The UV detection of Sirolimus was at 278(277.78) nm. Sirolimus coated drug eluting stents, MRM (Multiple reaction monitoring) transition of Sirolimus m/z 936.83,208.84 was selected to obtain maximum sensitivity. LC/MS/MS results exhibited consistency in drug content on the stent surface. In-vitro release kinetic indicated the release of Sirolimus in 41 days from the date of implanted. Drug release was found at the first day, burst release was observed at 7th day of implantation. This study involved pharmacological coating of stents, based on the notion that sustained systemic local delivery of anti-proliferative agents. LC-MS/MS method has been successfully used in the pharmacokinetic analysis of Sirolimus coated drug eluting stents. Copyright © 2009 John Wiley & Sons, Ltd. [source] Liquid chromatography-tandem mass spectrometry for the determination of a new oxazolidinone antibiotic DA-7867 in human plasmaBIOMEDICAL CHROMATOGRAPHY, Issue 2 2004Hye Young Ji Abstract A liquid chromatography-tandem mass spectrometric (LC/MS/MS) method for the determination of a new ox-azolidinone antibiotic DA-7867, (S)-[N -3-(4-(2-(1-methyl-5-tetrazolyl)-pyridine-5-yl)-3-,uorophenyl)-2-oxo-5-oxazolidinyl]methyl acetamide, in human plasma was developed. DA-7867 and internal standard, linezolid, were extracted from human plasma with ethyl acetate at acidic pH. A reverse-phase LC separation was performed on Luna C8 column with the mixture of acetonitrile,ammonium formate (10 mm, pH 4.5; 35:65, v/v) as mobile phase. The analytes were determined using an electrospray ionization tandem mass spectrometry in the multiple-reaction-monitoring mode. The lower limits of quanti,cation for DA-7867 was 2.5 ng/mL. The single liquid,liquid extraction quantitatively recovered DA-7867 and internal standard from plasma samples at the ranges of 82.2,86.7%. DA-7867 was stable in blank human plasma at room temperature for 24 h and following three freeze,thaw cycles. Copyright © 2003 John Wiley & Sons, Ltd. [source] Ethyl glucuronide in hair.ADDICTION, Issue 6 2009A sensitive, specific marker of chronic heavy drinking ABSTRACT Aims This study aims to define a cut-off concentration for ethyl glucuronide in hair to determine if there was a history of heavy drinking. Settings Pavia, Italy. Participants We analysed hair samples from 98 volunteers among teetotallers, social drinkers and heavy drinkers, whose ethanol daily intake (EDI) was estimated by means of a written questionnaire. Measurements Ethyl glucuronide hair concentration (HEtG) was measured by liquid chromatography-tandem mass spectrometry (lower limit of quantification: 3 pg/mg) using a fully validated method. Findings The HEtG level providing the best compromise between sensitivity (0.92) and specificity (0.96) at detecting an EDI of 60 g or higher during the last 3 months was 27 pg/mg. None of the factors examined among those known to affect ethanol metabolism and/or the diagnostic power of other markers of ethanol use or hair analyses, including age, gender, body mass index, tobacco smoke, prevalent beverage, hair colour, cosmetic treatments and hygienic habits was found to influence marker performance significantly. However, the slight differences in HEtG performance observed for some factors (e.g. body mass index, smoke and hair treatments) require further studies on larger groups of individuals in order to assess their influence more precisely. Conclusions Our results confirm further that HEtG is a sensitive and specific marker of chronic heavy drinking. [source] Urinary ethyl glucuronide (EtG) and ethyl sulphate (EtS) assessment: valuable tools to improve verification of abstention in alcohol-dependent patients during in-patient treatment and at follow-upsADDICTION, Issue 6 2009Klaus Junghanns ABSTRACT Aims The aims of this study were (i) to assess the effect of additional urinary ethyl glucuronide (EtG) and ethyl sulphate (EtS) assessment on diagnosed relapse rates in detoxified alcohol-dependent patients; and (ii) to compare dropout rates between EtG- and EtS-negative and -positive patients. Design Two studies on detoxified alcohol-dependent patients. If patients had no indication of relapse they were asked for a urinary sample at discharge from in-patient treatment 3, 6 and 12 weeks after discharge (study 1) and 1, 3 and 6 weeks after discharge (study 2), respectively. Setting Department of Psychiatry, University of Luebeck, Germany. Participants A total of 107 and 32 detoxified alcohol-dependent patients having participated in a 3-week in-patient motivation enhancement programme. Measurement Personal interviews, breathalyzer tests, assessment of urinary EtG and EtS with liquid chromatography-tandem mass spectrometry (LC-MS/MS analysis). Finding Urinary EtG and EtS were always positive at the same time. In the first study 13.5% of the patients were already positive before being discharged from hospital. At the follow-ups 3, 6 and 12 weeks after discharge 12.2, 19.4 and 28.0%, respectively, of the patients coming to the follow-up and denying relapse were positive on urinary EtG and EtS. In the second study, of those patients showing up for follow-up after 1 week and denying relapse, EtG and EtS were positive in four cases (17.4%). Only one EtG- and EtS-positive relapser (3.1%) came to the next follow-ups. In both studies the rates of detected relapses were significantly higher for early follow-ups if urinary EtG and EtS results were considered additionally. Dropout rates until the next follow-up were significantly higher among positive than EtG- and EtS-negative patients. Conclusion Urinary EtG and EtS improve verification of abstinence in studies of alcohol-dependent patients. [source] Disposition of perfluorinated acid isomers in sprague-dawley rats; Part 1: Single doseENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 3 2009Jonathan P. Benskin Abstract Perfluorinated acids (PFAs) and their precursors (PFA-precursors) exist in the environment as linear and multiple branched isomers. These isomers are hypothesized to have different biological properties, but no isomer-specific data are currently available. The present study is the first in a two-part project examining PFA isomer-specific uptake, tissue distribution, and elimination in a rodent model. Seven male Sprague-Dawley rats were administered a single gavage dose of approximately 500 ,g/kg body weight perfluorooctane sulfonate (C8F17SO3,, PFOS), perfluorooctanoic acid (C7F15CO2H, PFOA), and perfluorononanoic acid (C8F17CO2H, PFNA) and 30 ,g/kg body weight perfluorohexane sulfonate (C6F13SO3,, PFHxS). Over the subsequent 38 d, urine, feces, and tail-vein blood samples were collected intermittently, while larger blood volumes and tissues were collected on days 3 and 38 for isomer analysis by high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS). For all PFAs, branched isomers generally had lower blood depuration half-lives than the corresponding linear isomer. The most remarkable exception was for the PFOS isomer containing an alpha-perfluoromethyl branch (1m -PFOS), which was threefold more persistent than linear PFOS, possibly due to steric shielding of the hydrophilic sulfonate moiety. For perfluoromonomethyl-branched isomers of PFOS, a structure,property relationship was observed whereby branching toward the sulfonate end of the perfluoroalkyl chain resulted in increased half-lives. For PFHxS, PFOA, and PFOS, preferential elimination of branched isomers occurred primarily via urine, whereas for PFNA preferential elimination of the isopropyl isomer occurred via both urine and feces. Changes in the blood isomer profiles over time and their inverse correlation to isomer elimination patterns in urine, feces, or both provided unequivocal evidence of significant isomer-specific biological handling. Source assignment based on PFA isomer profiles in biota must therefore be conducted with caution, because isomer profiles are unlikely to be conserved in biological samples. [source] Wastewater treatment plants as a pathway for aquatic contamination by pharmaceuticals in the Ebro river basin (Northeast Spain)ENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 8 2007Meritxell Gros Abstract The occurrence of 28 pharmaceuticals of major human consumption in Spain, including analgesics and anti-inflam-matories, lipid regulators, psychiatric drugs, antibiotics, antihistamines, and ,-blockers, was assessed along the Ebro river basin, one of the biggest irrigated lands in that country. Target compounds were simultaneously analyzed by off-line solid-phase extraction, followed by liquid chromatography-tandem mass spectrometry. The loads of detected pharmaceuticals and their removal rates were studied in seven wastewater treatment plants (WWTPs) located in the main cities along the basin. Total loads ranged from 2 to 5 and from 0.5 to 1.5 g/d/1,000 inhabitants in influent and effluent wastewaters, respectively. High removal rates (60,90%) were achieved mainly for analgesics and anti-inflammatories. The other groups showed lower rates, ranging from 20 to 60%, and in most cases, the antiepileptic carbamazepine, macrolide antibiotics, and trimethoprim were not eliminated at all. Finally, the contribution of WWTP effluents to the presence of pharmaceuticals in receiving river waters was surveyed. In receiving surface water, the most ubiquitous compounds were the analgesics and anti-inflammatories ibuprofen, diclofenac, and naproxen; the lipid regulators bezafibrate and gemfibrozil; the antibiotics erythromycin, azithromycin, sulfamethoxazole, trimethoprim, and less frequently, ofloxacin; the antiepileptic carbamazepine; the antihistamine ranitidine; and the ,-blockers atenolol and sotalol. Although levels found in WWTP effluents ranged from low ,g/L to high ng/L, pharmaceuticals in river waters occurred at levels at least one order of magnitude lower (low ng/L range) because of dilution effect. From the results obtained, it was proved that WWTP are hot spots of aquatic contamination concerning pharmaceuticals of human consumption. [source] Dietary accumulation of perfluorinated acids in juvenile rainbow trout (Oncorhynchus mykiss)ENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 1 2003Jonathan W. Martin Abstract Perfluorinated acids (PFAs) recently have emerged as persistent global contaminants after their detection in wildlife and humans from various geographic locations. The highest concentrations of perfluorooctane sulfonate are characteristically observed in high trophic level organisms, indicating that PFAs may have a significant bioaccumulation potential. To examine this phenomenon quantitatively, we exposed juvenile rainbow trout (Oncorhynchus mykiss) simultaneously to a homologous series of perfluoroalkyl carboxylates and sulfonates for 34 d in the diet, followed by a 41-d depuration period. Carcass and liver concentrations were determined by using liquid chromatography-tandem mass spectrometry, and kinetic rates were calculated to determine compound-specific bioaccumulation parameters. Depuration rate constants ranged from 0.02 to 0.23/d, and decreased as the length of the fluorinated chain increased. Assimilation efficiency was greater than 50% for all test compounds, indicating efficient absorption from food. Bioaccumulation factors (BAFs) ranged from 0.038 to 1.0 and increased with length of the perfluorinated chain; however, BAFs were not statistically greater than 1 for any PFA. Sulfonates bioaccumulated to a greater extent than carboxylates of equivalent perfluoroalkyl chain length, indicating that hydrophobicity is not the sole determinant of PFA accumulation potential and that the acid function must be considered. Dietary exposure will not result in biomagnification of PFAs in juvenile trout, but extrapolation of these bioaccumulation parameters to larger fish and homeothermic organisms should not be performed. [source] Measurement-specific bioavailable testosterone using concanavalin A precipitation: Comparison of calculated and assayed bioavailable testosteroneINTERNATIONAL JOURNAL OF UROLOGY, Issue 11 2009Kenrou Yamamoto Objective: To assess the value of calculated bioavailable testosterone (cBT) and assayed BT (aBT) for the diagnosis of late-onset hypogonadism (LOH) in middle-aged and elderly subjects. Methods: In order to assay serum BT, sex hormone-binding globulin was precipitated with concanavalin-A and then testosterone was measured using liquid chromatography-tandem mass spectrometry. To validate the non-sex-hormone-binding-globulin-bound testosterone, gel filtration chromatography and concanavalin-A sepharose were used. Following this validation, the usefulness between aBT and cBT was evaluated in clinical samples. Results: Eighty-eight healthy male volunteers (mean age 65.6 years, range: 50,86) were recruited for this study. A significant correlation was found between cBT and aBT (R2 = 0.53, P < 0.01). Mean value ratio (cBT/aBT) was 2.48. Both cBT (R2 = 0.122) and aBT (R2 = 0.251) decreased with age. Variations in aBT were less marked than those for cBT, suggesting that aBT can be used to determine age-related reduced testosterone levels. Conclusion: aBT levels are more reliable than cBT levels for the diagnosis of LOH in middle-aged and elderly subjects. [source] Studies on the metabolism of the ,9-tetrahydrocannabinol precursor ,9-tetrahydrocannabinolic acid A (,9-THCA-A) in rat using LC-MS/MS, LC-QTOF MS and GC-MS techniquesJOURNAL OF MASS SPECTROMETRY (INCORP BIOLOGICAL MASS SPECTROMETRY), Issue 10 2009Julia Jung Abstract In Cannabis sativa, ,9-Tetrahydrocannabinolic acid-A (,9-THCA-A) is the non-psychoactive precursor of ,9-tetrahydrocannabinol (,9-THC). In fresh plant material, about 90% of the total ,9-THC is available as ,9-THCA-A. When heated (smoked or baked), ,9-THCA-A is only partially converted to ,9-THC and therefore, ,9-THCA-A can be detected in serum and urine of cannabis consumers. The aim of the presented study was to identify the metabolites of ,9-THCA-A and to examine particularly whether oral intake of ,9-THCA-A leads to in vivo formation of ,9-THC in a rat model. After oral application of pure ,9-THCA-A to rats (15 mg/kg body mass), urine samples were collected and metabolites were isolated and identified by liquid chromatography-mass spectrometry (LC-MS), liquid chromatography-tandem mass spectrometry (LC-MS/MS) and high resolution LC-MS using time of flight-mass spectrometry (TOF-MS) for accurate mass measurement. For detection of ,9-THC and its metabolites, urine extracts were analyzed by gas chromatography-mass spectrometry (GC-MS). The identified metabolites show that ,9-THCA-A undergoes a hydroxylation in position 11 to 11-hydroxy-,9-tetrahydrocannabinolic acid-A (11-OH-,9-THCA-A), which is further oxidized via the intermediate aldehyde 11-oxo-,9-THCA-A to 11-nor-9-carboxy-,9-tetrahydrocannabinolic acid-A (,9-THCA-A-COOH). Glucuronides of the parent compound and both main metabolites were identified in the rat urine as well. Furthermore, ,9-THCA-A undergoes hydroxylation in position 8 to 8-alpha- and 8-beta-hydroxy-,9-tetrahydrocannabinolic acid-A, respectively, (8,-Hydroxy-,9-THCA-A and 8,-Hydroxy-,9-THCA-A, respectively) followed by dehydration. Both monohydroxylated metabolites were further oxidized to their bishydroxylated forms. Several glucuronidation conjugates of these metabolites were identified. In vivo conversion of ,9-THCA-A to ,9-THC was not observed. Copyright © 2009 John Wiley & Sons, Ltd. [source] Characterization of in vitro and in vivo metabolic pathways of the investigational anticancer agent, 2-methoxyestradiolJOURNAL OF PHARMACEUTICAL SCIENCES, Issue 7 2007Nehal J. Lakhani Abstract The aim of this study was to characterize the metabolic pathways of 2-methoxyestradiol (2ME2), an investigational anticancer drug. In vitro metabolism studies were performed by incubation of 2ME2 with human liver microsomes under various conditions and metabolite identification was performed using liquid chromatography-tandem mass spectrometry. In microsomal mixtures, four major oxidative metabolites and two glucuronic acid conjugates were observed originating from 2ME2. Human liver S9 protein fraction was used to screen for in vitro sulfation but no prominent conjugates were observed. The total hepatic clearance as estimated using the well-stirred model was approximately 712 mL/min. In vivo metabolism, assessed using 24-h collections of urine from cancer patients treated with 2ME2 revealed that <0.01% of the total administered dose of 2ME2 is excreted unchanged in urine and about 1% excreted as glucuronides. Collectively, this suggests that glucuronidation and subsequent urinary excretion are elimination pathways for 2ME2. © 2007 Wiley-Liss, Inc. and the American Pharmacists Association J Pharm Sci 96: 1821,1831, 2007 [source] Attenuation of ciclosporin-induced nephrotoxicity by dietary supplementation of seal oil in Sprague-Dawley ratsJOURNAL OF PHARMACY AND PHARMACOLOGY: AN INTERNATI ONAL JOURNAL OF PHARMACEUTICAL SCIENCE, Issue 11 2005Wei Yang Fish oil, rich in omega-3 (n-3) polyunsaturated fatty acids (PUFAs), has been reported to attenuate nephrotoxicity induced by ciclosporin (cyclosporine A). Harp seal oil is a rich source of n-3 PUFAs. This study investigated the ability of dietary seal oil to reduce nephrotoxicity caused by ciclosporin. Sprague-Dawley rats were maintained on a standard diet (with sunflower oil as lipid, SFO) or a diet enriched with seal oil (with 85% seal oil and 15% sunflower oil as lipid, SO) for four weeks before and four weeks after intravenous administration of ciclosporin (15 mg kg,1 daily). Kidney function was assessed by measuring blood urea nitrogen, creatinine clearance, urinary N -acetyl-1-,- d -glucosaminidase, 6-keto-prostaglandin F1,, thromboxane B2 and malondialdehyde. Systolic blood pressure (SBP) was monitored. Ciclosporin concentrations in blood were measured using liquid chromatography-tandem mass spectrometry (LC-MS/MS). The fatty acid compositions of the diets and erythrocyte membranes were analysed by gas chromatography (GC). The results showed that nephrotoxicity was induced by ciclosporin in rats maintained on both SO and SFO diets. However, rats fed on SO diet endured less toxicity than those on SFO diet. The n-3 and n-6 PUFAs in the erythrocyte membrane of rats maintained on SO diet were found to be 10.79% and 11.93%, while those in rats maintained on SFO diet were found to be 1.67% and 22.71%, respectively. In conclusion, dietary supplementation of seal oil was found to reduce ciclosporin-induced nephrotoxicity in rats. [source] Phosphatidylethanol and Alcohol Consumption in Reproductive Age WomenALCOHOLISM, Issue 3 2010Scott H. Stewart Background:, Fetal alcohol disorders are preventable, but self-reported alcohol consumption can be misleading and impede effective treatment. Biomarkers represent an alternative method for assessing alcohol use, and this study evaluated the relationship between blood phosphatidylethanol (PEth) and alcohol use in a sample of reproductive age women. Methods:, Alcohol use was estimated by validated self-report methods in 80 nonpregnant women ages 18 to 35. PEth was measured by a contracted laboratory using a liquid chromatography-tandem mass spectrometry assay. Regression methods appropriate for the distribution of PEth were used to define its relationship to alcohol consumption during the prior 2 weeks and explore the effects of drinking patterns on this association. Receiver operating characteristic analysis was used to estimate the sensitivity of PEth for various drinking levels at 95% specific cutoffs. Results:, PEth had a positive linear association with grams of alcohol consumed (p < 0.001), and was detectable in 93% of subjects consuming an average of 2 or more drinks per day. The relationship between total alcohol consumption and PEth may be stronger in women with recent heavy drinking days. The relationship between drinking and PEth varied considerably between individuals, and sensitivity for a certain amount of drinking was low at a highly specific cutoff concentration. Conclusions:, PEth is a highly sensitive indicator of moderate and heavy alcohol consumption in reproductive age women and may complement the use of self-report alcohol screens when additional objective markers of alcohol use are desirable. However, choosing a highly valid cutoff concentration for PEth to differentiate various levels of alcohol consumption may not be feasible. [source] A Critical Evaluation of Influence of Ethanol and Diet on Salsolinol Enantiomers in Humans and RatsALCOHOLISM, Issue 2 2010Jeongrim Lee Background:, (R/S)-Salsolinol (SAL), a condensation product of dopamine (DA) with acetaldehyde, has been speculated to have a role in the etiology of alcoholism. Earlier studies have shown the presence of SAL in biological fluids and postmortem brains from both alcoholics and nonalcoholics. However, the involvement of SAL in alcoholism has been controversial over several decades, since the reported SAL levels and their changes after ethanol exposure were not consistent, possibly due to inadequate analytical procedures and confounding factors such as diet and genetic predisposition. Using a newly developed mass spectrometric method to analyze SAL stereoisomers, we evaluated the contribution of ethanol, diet, and genetic background to SAL levels as well as its enantiomeric distribution. Methods:, Simultaneous measurement of SAL enantiomers and DA were achieved by high performance liquid chromatography-tandem mass spectrometry (HPLC/MS/MS). Plasma samples were collected from human subjects before and after banana (a food rich in SAL) intake, and during ethanol infusion. Rat plasma and brain samples were collected at various time points after the administration of SAL or banana by gavage. The brain parts including nucleus accumbens (NAC) and striatum (STR) were obtained from alcohol-non-preferring (NP) or alcohol-preferring (P) rats as well as P-rats which had a free access to ethanol (P-EtOH). Results:, Plasma SAL levels were increased significantly after banana intake in humans. Consistently, administration of banana to rats also resulted in a drastic increase of plasma SAL levels, whereas brain SAL levels remained unaltered. Acute ethanol infusion did not change SAL levels or R/S ratio in plasma from healthy humans. The levels of both SAL isomers and DA were significantly lower in the NAC of P rats in comparison to NP rats. The SAL levels in NAC of P rats remained unchanged after chronic free-choice ethanol drinking. There were decreasing trends of SAL in STR and DA in both brain regions. No changes in enantiomeric ratio were observed after acute or chronic ethanol exposure. Conclusions:, SAL from dietary sources is the major contributor to plasma SAL levels. No significant changes of SAL plasma levels or enantiomeric distribution after acute or chronic ethanol exposure suggest that SAL may not be a biomarker for ethanol drinking. Significantly lower SAL and DA levels observed in NAC of P rats may be associated with innate alcohol preference. [source] Simultaneous determination of yohimbine, sildenafil, vardenafil and tadalafil in dietary supplements using high-performance liquid chromatography-tandem mass spectrometryJOURNAL OF SEPARATION SCIENCE, JSS, Issue 14 2010Ying Zhang Abstract A simple and sensitive method was developed for determination of illegal adulterants (yohimbine, sildenafil, vardenafil and tadalafil) in dietary supplements by HPLC-MS/MS. The separation was achieved on a C18 column with the mobile phase consisting of acetonitrile and 0.1% acetic acid aqueous solution with a gradient elution at a flow rate of 0.5,mL/min. The analytes were quantified and identified by two characteristic transitions using the multiple-reaction monitoring mode. The recoveries of the analytes ranged from 77.5 to 109.3% with the RSD less than 8.1% (n=6). The method has been successfully applied to screen illegal adulterations of natural dietary supplements. [source] Highly sensitive determination of tetrabromobisphenol A and bisphenol A in environmental water samples by solid-phase extraction and liquid chromatography-tandem mass spectrometryJOURNAL OF SEPARATION SCIENCE, JSS, Issue 11 2010Ru-Song Zhao Abstract Using bamboo-activated charcoal as SPE adsorbent, a novel SPE method was developed for the sensitive determination of tetrabromobisphenol A and bisphenol A in environmental water samples by rapid-resolution LC-ESI-MS/MS. Important parameters influencing extraction efficiency, including type of eluent, eluent volume, sample pH, volume and flow rate, were investigated and optimized. Under the optimal extraction conditions (eluent: 8,mL methanol, pH: 7; flow rate: 4,mL/min; sample volume: 100,mL), low LODs (0.01,0.02,ng/mL), good repeatability (6.2,8.3%) and wide linearity range (0.10,10,ng/mL) were obtained. Satisfied results were achieved when the proposed method was applied to determine the two target compounds in real-world environmental water samples with spiked recoveries over the range of 80.5,119.8%. All these facts indicate that trace determination of tetrabromobisphenol A and bisphenol A in real-world environmental water samples can be realized by bamboo-activated charcoal SPE-rapid resolution-LC-ESI-MS/MS. [source] Determination of methylene blue residues in aquatic products by liquid chromatography-tandem mass spectrometryJOURNAL OF SEPARATION SCIENCE, JSS, Issue 23-24 2009Jin-Zhong Xu Abstract A method for the determination and confirmation of methylene blue (MB) in aquatic products was developed. Residues of MB were extracted from homogenized tissues with acetonitrile/sodium acetate buffer solution, and simply cleaned up with dichloromethane liquid/liquid extraction. After concentration and dissolution, the sample solutions were cleaned up by the neutral alumina and weak cation-exchange solid phase extraction (SPE) cartridge, prior to LC-MS/MS analysis. MB was determined at 1.0,20,,g/kg in eel, toasted eel and shrimp, with a limit of quantification of 0.5,,g/kg. Recovery for MB was between 73.0% and 108.3%. This method is fast, exact and sensitive. It can be applied to determine MB in aquatic products. [source] Detection of Recent Ethanol Intake With New Markers: Comparison of Fatty Acid Ethyl Esters in Serum and of Ethyl Glucuronide and the Ratio of 5-Hydroxytryptophol to 5-Hydroxyindole Acetic Acid in UrineALCOHOLISM, Issue 5 2005K Borucki Background: At present, recent ethanol consumption can be routinely detected with certainty only by direct measurement of ethanol concentration in blood or urine. Because ethanol is rapidly eliminated from the circulation, however, the time span for this detection is in the range of hours. Several new markers have been proposed to extend the detection interval, but their characteristics have not yet justified their use in routine clinical practice. We therefore investigated three new markers and compared their kinetics and sensitivities: (1) fatty acid ethyl esters (FAEEs) in serum, (2) ethyl glucuronide (EtG) in urine, and (3) the ratio of 5-hydroxytryptophol to 5-hydroxyindole acetic acid (5-HTOL/5-HIAA) in urine. Methods: Seventeen healthy men participated in a drinking experiment. Blood and urine samples were collected twice daily on three consecutive days and once daily on days 4 and 5. Ethanol concentration was determined by gas chromatography, FAEE levels, by gas chromatography with mass spectrometry, EtG concentration, by liquid chromatography-tandem mass spectrometry, and 5-HTOL/5-HIAA ratio, by high-performance liquid chromatography. Results: The peak serum ethanol concentrations of the subjects ranged from 5.4 to 44.7 mmol/liter (mean ± SD, 30.1 ± 9.1 mmol/liter). In the case of the serum ethanol determination, 100% sensitivity was reached only immediately after the end of the drinking experiment, and in the case of FAEE levels and 5-HTOL/5-HIAA ratio, it tested for 6.7 hr after the end of the ethanol intake. Thereafter, these latter parameters declined until 15.3 hr (FAEEs) and 29.4 hr (5-HTOL/5-HIAA), subsequently remaining in a stable range until 78.5 hr without further decrease. In contrast, EtG concentration showed 100% sensitivity until 39.3 hr and thereafter decreased, falling to below the limit of quantification of 0.1 mg/liter at 102.5 hr. Conclusion: After moderate drinking, EtG in the urine proved to be a superior marker of recent ethanol consumption in healthy subjects. This is because EtG is a direct ethanol metabolite, it occurs in the urine only when ethanol has been consumed, and its sensitivity remains at the level of 100% for 39.3 hr. [source] Pharmacokinetic profile and behavioral effects of gabapentin in the horseJOURNAL OF VETERINARY PHARMACOLOGY & THERAPEUTICS, Issue 5 2010R. L. TERRY Terry, R. L., McDonnell, S. M., van Eps, A. W., Soma, L. R., Liu, Y., Uboh, C. E., Moate, P. J., Driessen, B. Pharmacokinetic profile and behavioral effects of gabapentin in the horse. J. vet. Pharmacol. Therap. 33, 485,494. Gabapentin is being used in horses although its pharmacokinetic (PK) profile, pharmacodynamic (PD) effects and safety in the equine are not fully investigated. Therefore, we characterized PKs and cardiovascular and behavioral effects of gabapentin in horses. Gabapentin (20 mg/kg) was administered i.v. or p.o. to six horses using a randomized crossover design. Plasma gabapentin concentrations were measured in samples collected 0,48 h postadministration employing liquid chromatography-tandem mass spectrometry. Blood pressures, ECG, and sedation scores were recorded before and for 12 h after gabapentin dosage. Nineteen quantitative measures of behaviors were evaluated. After i.v. gabapentin, the decline in plasma drug concentration over time was best described by a 3-compartment mammillary model. Terminal elimination half-life (t1/2,) was 8.5 (7.1,13.3) h. After p.o. gabapentin terminal elimination half-life () was 7.7 (6.7,11.9) h. The mean oral bioavailability of gabapentin (±SD) was 16.2 ± 2.8% indicating relatively poor absorption of gabapentin following oral administration in horses. Gabapentin caused a significant increase in sedation scores for 1 h after i.v. dose only (P < 0.05). Among behaviors, drinking frequency was greater and standing rest duration was lower with i.v. gabapentin (P < 0.05). Horses tolerated both i.v. and p.o. gabapentin doses well. There were no significant differences in and . Oral administration yielded much lower plasma concentrations because of low bioavailability. [source] Detection and pharmacokinetics of tetrahydrogestrinone in horsesJOURNAL OF VETERINARY PHARMACOLOGY & THERAPEUTICS, Issue 2 2009M. MACHNIK The anti-doping rules of national and international sport federations ban any use of tetrahydrogestrinone (THG) in human as well as in horse sports. Initiated by the THG doping scandals in human sports a method for the detection of 3-keto-4,9,11-triene steroids in horse blood and urine was developed. The method comprises the isolation of the analytes by a combination of solid phase and liquid,liquid extraction after hydrolysis and solvolysis of the steroid conjugates. The concentrations of THG in blood and urine samples were measured by liquid chromatography-tandem mass spectrometry (LC-MS/MS). A THG excretion study on horses was conducted to verify the method capability for the analysis of postadministration urine samples. In addition, blood samples were collected to allow for determination of the pharmacokinetics of THG in horses. Following the administration of a single oral dose of 25 ,g THG per kg bodyweight to 10 horses, samples were collected at appropriate intervals. The plasma levels of THG reached maximal concentrations of 1.5,4.8 ng/mL. Twenty-four hours after the administration plasma levels returned to baseline. In urine, THG was detectable for 36 h. Urinary peak concentrations of total THG ranged from 16 to 206 ng/mL. For the 10 horses tested, the mean plasma clearance of THG was 2250 mL/h/kg and the plasma elimination half-life was 1.9 h. [source] Pharmacokinetics of boldenone and stanozolol and the results of quantification of anabolic and androgenic steroids in race horses and nonrace horsesJOURNAL OF VETERINARY PHARMACOLOGY & THERAPEUTICS, Issue 2 2007L. R. SOMA Anabolic steroids (ABS) boldenone (BL; 1.1 mg/kg) and stanozolol (ST; 0.55 mg/kg) were administered i.m. to horses and the plasma samples collected up to 64 days. Anabolic steroids and androgenic steroids (ANS) in plasma were quantified using liquid chromatography-tandem mass spectrometry (LC-MS/MS). The limit of detection of all analytes was 25 pg/mL. The median absorption (t1/2,) and elimination (t1/2e) half-lives for BL were 8.5 h and 123.0 h, respectively, and the area under the plasma concentration,time curve () was 274.8 ng·h/mL. The median t1/2e for ST was 82.1 h and the was 700.1 ng·h/mL. Peak mean () plasma concentrations (Cmax) for BL and ST were 1127.8 and 4118.2 pg/mL, respectively. Quantifiable concentrations of ABS and ANS were found in 61.7% of the 988 plasma samples tested from race tracks. In 17.3% of the plasma samples two or more ABS or ANS were quantifiable. Testosterone (TES) concentrations mean () in racing and nonracing intact males were 241.3 ± 61.3 and 490.4 ± 35.1 pg/mL, respectively. TES was not quantified in nonracing geldings and female horses, but was in racing females and geldings. Plasma concentrations of endogenous 19-nortestosterone (nandrolone; NA) from racing and nonracing males were 50.2 ± 5.5 and 71.8 ± 4.6 pg/mL, respectively. [source] Pharmacokinetics of altrenogest in horsesJOURNAL OF VETERINARY PHARMACOLOGY & THERAPEUTICS, Issue 1 2007M. MACHNIK The Federation Equestre Internationale has permitted the use of altrenogest in mares for the control of oestrus. However, altrenogest is also suspicious to misuse in competition horses for its potential anabolic effects and suppression of typical male behaviour, and thus is a controlled drug. To investigate the pharmacokinetics of altrenogest in horses we conducted an elimination study. Five oral doses of 44 ,g/kg altrenogest were administered to 10 horses at a dose interval of 24 h. Following administration blood and urine samples were collected at appropriate intervals. Altrenogest concentrations were measured by liquid chromatography-tandem mass spectrometry. The plasma levels of altrenogest reached maximal concentrations of 23,75 ng/mL. Baseline values were achieved within 3 days after the final administration. Urine peak concentrations of total altrenogest ranged from 823 to 3895 ng/mL. Twelve days after the final administration concentrations were below the limit of detection (ca 2 ng/mL). [source] Automation of nanoflow liquid chromatography-tandem mass spectrometry for proteome analysis by using a strong cation exchange trap columnPROTEINS: STRUCTURE, FUNCTION AND BIOINFORMATICS, Issue 4 2007Xiaogang Jiang Abstract An approach was developed to automate sample introduction for nanoflow LC-MS/MS (,LC-MS/MS) analysis using a strong cation exchange (SCX) trap column. The system consisted of a 100,,m id×2,cm SCX trap column and a 75,,m id×12,cm C18 RP analytical column. During the sample loading step, the flow passing through the SCX trap column was directed to waste for loading a large volume of sample at high flow rate. Then the peptides bound on the SCX trap column were eluted onto the RP analytical column by a high salt buffer followed by RP chromatographic separation of the peptides at nanoliter flow rate. It was observed that higher performance of separation could be achieved with the system using SCX trap column than with the system using C18 trap column. The high proteomic coverage using this approach was demonstrated in the analysis of tryptic digest of BSA and yeast cell lysate. In addition, this system was also applied to two-dimensional separation of tryptic digest of human hepatocellular carcinoma cell line SMMC-7721 for large scale proteome analysis. This system was fully automated and required minimum changes on current ,LC-MS/MS system. This system represented a promising platform for routine proteome analysis. [source] Shotgun proteomic analysis of Chlamydia trachomatisPROTEINS: STRUCTURE, FUNCTION AND BIOINFORMATICS, Issue 6 2005Paul Skipp Abstract Chlamydiae are widespread bacterial pathogens responsible for a broad range of diseases, including sexually transmitted infections, pneumonia and trachoma. To validate the existence of hitherto hypothetical proteins predicted from recent chlamydial genome sequencing projects and to examine the patterns of expression of key components at the protein level, we have surveyed the expressed proteome of Chlamydia trachomatis strain,L2. A combination of two-dimensional gel analysis, multi-dimensional protein identification (MudPIT) and nanocapillary liquid chromatography-tandem mass spectrometry allowed a total of 328,chlamydial proteins to be unambiguously assigned. Proteins identified as being expressed in the metabolically inert form, elementary body, of Chlamydia include the entire set of predicted glycolytic enzymes, indicating that metabolite flux rather than de novo synthesis of this pathway is triggered upon infection of host cells. An enzyme central to cell wall biosynthesis was also detected in the intracellular form, reticulate body, of Chlamydia, suggesting that the peptidoglycan is produced during growth within host cells. Other sets of proteins identified include 17 outer membrane-associated proteins of potential significance in vaccine studies and 67,proteins previously annotated as hypothetical or conserved hypothetical. Taken together, ,35% of the predicted proteome for C.,trachomatis has been experimentally verified, representing the most extensive survey of any chlamydial proteome to date. [source] Improved proteome coverage by using high efficiency cysteinyl peptide enrichment: The human mammary epithelial cell proteomePROTEINS: STRUCTURE, FUNCTION AND BIOINFORMATICS, Issue 5 2005Tao Liu Abstract Automated multidimensional capillary liquid chromatography-tandem mass spectrometry (LC-MS/MS) has been increasingly applied in various large scale proteome profiling efforts. However, comprehensive global proteome analysis remains technically challenging due to issues associated with sample complexity and dynamic range of protein abundances, which is particularly apparent in mammalian biological systems. We report here the application of a high efficiency cysteinyl peptide enrichment (CPE) approach to the global proteome analysis of human mammary epithelial cells (HMECs) which significantly improved both sequence coverage of protein identifications and the overall proteome coverage. The cysteinyl peptides were specifically enriched by using a thiol-specific covalent resin, fractionated by strong cation exchange chromatography, and subsequently analyzed by reversed-phase capillary LC-MS/MS. An HMEC tryptic digest without CPE was also fractionated and analyzed under the same conditions for comparison. The combined analyses of HMEC tryptic digests with and without CPE resulted in a total of 14,416 confidently identified peptides covering 4294 different proteins with an estimated 10%,gene coverage of the human genome. By using the high efficiency CPE, an additional 1096 relatively low abundance proteins were identified, resulting in 34.3% increase in proteome coverage; 1390,proteins were observed with increased sequence coverage. Comparative protein distribution analyses revealed that the CPE method is not biased with regard to protein Mr,, pI, cellular location, or biological functions. These results demonstrate that the use of the CPE approach provides improved efficiency in comprehensive proteome-wide analyses of highly complex mammalian biological systems. [source] Mining biomarkers in human sera using proteomic toolsPROTEINS: STRUCTURE, FUNCTION AND BIOINFORMATICS, Issue 1 2004Rulin Zhang Abstract One of the major difficulties in mining low abundance biomarkers from serum or plasma is due to the fact that a small number of proteins such as albumin, ,2-macroglobulin, transferrin, and immunoglobulins, may represent as much as 80% of the total serum protein. The large quantity of these proteins makes it difficult to identify low abundance proteins in serum using traditional 2-dimensional electrophoresis. We recently used a combination of multidimensional liquid chromatography and gel electrophoresis coupled to matrix-assisted laser desorption/ionization-quadrupole-time of flight and Ion Trap liquid chromatography-tandem mass spectrometry to identify protein markers in sera of Alzheimer's disease (AD), insulin resistance/type-2 diabetes (IR/D2), and congestive heart failure (CHF) patients. We identified 8 proteins that exhibit higher levels in control sera and 36 proteins that exhibit higher levels in disease sera. For example, haptoglobin and hemoglobin are elevated in sera of AD, IR/D2, and CHF patients. The levels of several other proteins including fibrinogen and its fragments, alpha 2-macroglobulin, transthyretin, pro-platelet basic protein, protease inhibitors clade A and C, as well as proteins involved in the classical complement pathway such as complement C3, C4, and C1 inhibitor, were found to differ between IR/D2 and control sera. The sera levels of proteins, such as the 10 kDa subunit of vitronectin, alpha 1-acid glycoprotein, apolipoprotein B100, fragment of factor H, and histidine-rich glycoprotein were observed to be different between AD and controls. The differences observed in these biomarker candidates were confirmed by Western blot and the enzyme-linked immunosorbent assay. The biological meaning of the proteomic changes in the disease states and the potential use of these changes as diagnostic tools or for therapeutic intervention will be discussed. [source] Correlation between scores on Continuous Performance Test and plasma concentration for schizophrenic patients on risperidonePSYCHIATRY AND CLINICAL NEUROSCIENCES, Issue 2 2004PO SEE CHEN md Abstract, The purpose of the present paper was to evaluate the relationship between plasma antipsychotics concentration and cognitive task performance. This may provide valuable information for rational dosage titration. Literature on the relationship between plasma risperidone (RIS) concentration and performance on the Continuous Performance Test (CPT) remains scarce. Ten patients (four male, six female) were given RIS for more than 1 year. Steady-state plasma concentrations of the parent drug RIS and its active metabolite, 9-hydroxy-risperidone (9-OH-RIS), were measured using specific liquid chromatography-tandem mass spectrometry assay. Psychopathology, side-effects of extrapyramidal symptoms (EPS) and CPT were also assessed. A negative correlation was found between CPT performance and the plasma RIS, 9-OH-RIS and its active moiety (RIS + 9-OH-RIS) concentrations. Both RIS and 9-OH-RIS have an impact on the CPT performance of schizophrenic patients. Optimal active moiety plasma concentration for best cognitive performance needs further study. [source] Validation of salivary cortisol and testosterone assays in chimpanzees by liquid chromatography-tandem mass spectrometryAMERICAN JOURNAL OF PRIMATOLOGY, Issue 8 2009Nobuyuki Kutsukake Abstract Owing to its high temporal sensitivity, saliva has distinct advantages for measuring steroids, compared with other noninvasive samples such as urine and feces. Here, we report the validity of assaying salivary cortisol (C) and testosterone (T) using liquid chromatography-tandem mass spectrometry (LC-MS/MS) in captive male chimpanzees, Pan troglodytes. For both the C and T concentrations, we found positive relationships between saliva and plasma. The concentrations of C and T in saliva showed clear patterns of diurnal fluctuation, whereas those in urine and feces did not. These results suggest that the salivary steroid concentrations can be regarded as good indicators of circulating steroid levels. We also developed and validated an efficient method for collecting saliva samples from cotton rope. Although rope includes inherent steroid-like compounds and may affect the accuracy of steroid measurements, our rope-washing procedures effectively removed intrinsic steroidal materials. There was a significant association between the C and T concentrations measured from saliva collected from rope licked by the chimpanzees and those measured from saliva collected directly from the mouth. Salivary T values estimated by LC/MS-MS were similar to those measured by radioimmunoassay. The results indicate the usefulness of saliva as a noninvasive steroid measure and that steroids in the saliva of chimpanzees can be accurately measured by LC-MS/MS. Am. J. Primatol. 71:696,706, 2009. © 2009 Wiley-Liss, Inc. [source] Acute Toxic Herbal Intake in a Suicide Attempt and Fatal Refractory Ventricular ArrhythmiaBASIC AND CLINICAL PHARMACOLOGY & TOXICOLOGY, Issue 2 2010Antoine Strzelecki Repeated direct-current cardioversions were unsuccessful and no single anti-arrhythmic agent was effective for arrhythmia control. The routine blood toxicological screening was negative. Aconitine, the main toxin of Aconitum napellus was identified using a specific liquid chromatography-tandem mass spectrometry (LC-MS/MS) method. The whole blood concentration (24 ,g/l) was higher than those reported in other aconitine-related deaths. The patient had found information about the life-threatening nature of such a toxic herb intake on a free medical encyclopaedia online. [source] Highly sensitive determination of Schisandrin and Schisandrin B in plasma of rats after administration of Wurenchun (Fructus Schisandrae Chinensis Extracts) preparations by LC-ESI-MS/MSBIOMEDICAL CHROMATOGRAPHY, Issue 6 2010Jingling Tang Abstract A sensitive and specific method based on liquid chromatography-tandem mass spectrometry using electrospray ionization (LC-ESI-MS/MS) has been developed for the determination of Schisandrin and Schisandrin B in rat plasma. A 100,,L plasma sample was extracted by methyl tert-butyl ether after spiking the samples with nimodipine (internal standard) and performed on an XTerra®MS-C18 column (150,mm × 2.1,mm, 3.5,,m) with the mobile phase of acetonitrile,water,formic acid (80:20:0.2, v/v) at a flow rate of 0.2,mL/min in a run time of 8.5,min. The lower limit of quantification of the method was 40,ng/mL for Schisandrin and 20,ng/mL for Schisandrin B. The method showed reproducibility with intra-day and inter-day precision of less than 13.8% RSD, as well as accuracy, with inter- and intra-assay accuracies between 93.5 and 107.2%. Finally, the LC-ESI-MS/MS method was successfully applied to study the pharmacokinetics of Schisandrin and Schisandrin B in rats after administration of Wurenchun commercial formulations to rats. Copyright © 2009 John Wiley & Sons, Ltd. [source] Quercetin pharmacokinetics in humansBIOPHARMACEUTICS AND DRUG DISPOSITION, Issue 4 2008Young J. Moon Abstract The purpose of this study was to examine the pharmacokinetics of quercetin aglycone as well as its conjugated metabolites and to develop a population pharmacokinetic model for quercetin that incorporates enterohepatic recirculation. The stability of quercetin in different matrices at various temperatures and pH, and the quercetin content of six capsules of the herbal preparation Quercetin-500 Plus® were determined by HPLC. Subjects received quercetin 500,mg three times daily and blood and urine samples were obtained. The concentration of quercetin aglycone and conjugated metabolites were assayed using a liquid chromatography-tandem mass spectrometry assay. Pharmacokinetic parameters were determined using noncompartmental analysis with WinNonlin. A population compartment model incorporating input from the gallbladder was developed to account for the enterohepatic recirculation observed with quercetin. The oral clearance (CL/F) was high (3.5,×,104l/h) with an average terminal half-life of 3.5,h for quercetin. The plasma concentration versus time curves exhibited re-entry peaks. A one-compartment model that included enterohepatic recirculation best described the plasma data. This represents the first comprehensive evaluation of the pharmacokinetics and enterohepatic recirculation of quercetin in humans. Population pharmacokinetic models adapted for enterohepatic recirculation allowed an assessment of the magnitude and frequency of the enterohepatic recirculation process. Copyright © 2008 John Wiley & Sons, Ltd. [source] | ||||||||||||||||