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Monitoring Mode (monitoring + mode)
Kinds of Monitoring Mode Selected AbstractsANALYSIS AND FORMATION OF ACRYLAMIDE IN FRENCH FRIES AND CHICKEN LEGS DURING FRYINGJOURNAL OF FOOD BIOCHEMISTRY, Issue 5 2006W.H. CHUANG ABSTRACT The analysis and formation of acrylamide in French fries and chicken legs during frying were studied. Results showed that the most appropriate extraction solvent was ethyl acetate, with C-18 cartridge for purification and 5-mL deionized water as elution solvent. Dibromination of acrylamide followed by dehydrobromination to 2-bromopropionamide in the presence of triethylamine was necessary for subsequent analysis by gas chromatography,mass spectrometry. The most appropriate temperature programming condition was as follows: 70C in the beginning, raised to 150C at a rate of 10C/min, maintained for 1 min and to 240C at a rate of 30C/min, maintained for 5 min. Detection was carried out using selected-ion monitoring mode, and N,N -dimethylacrylamide was used as internal standard for quantification. French fries and the outer flour portion of chicken legs fried at 180C generated a higher level of acrylamide than at 160C. Compared to soybean oil and palm oil, a lower amount of acrylamide was produced in French fries and the outer flour portion of chicken legs fried in lard. However, no acrylamide was detected in the inner meat portion of fried chicken legs. [source] A Fatal Case of Suspected Anaphylaxis with Cefoperazone and Sulbactam: LC-MS AnalysisJOURNAL OF FORENSIC SCIENCES, Issue 1 2008Kenji Tsujikawa M.S. Abstract: Cefoperazone and sublactam are prescribed in combination and used in the treatment of moderate to severe bacterial infections. Serious anaphylaxis is a rare side effect. This report describes a fatal case of suspected anaphylaxis after intravenous administration of a combination of the two drugs. Heart blood was analyzed for cefoperazone by protein precipitation with acetonitrile and by liquid-liquid precipitation for sublactam after protein precipitation with aqueous acetonitrile, followed by tandem mass spectrometry in the product ion scan mode for identification and by liquid chromatography mass spectrometry in the selected ion monitoring mode for quantitation. Calibration curves for cefoperazone and sublactam were linear over the range 0.07 to 1.93 and 0.046 to 0.914 ,g/ml respectively. The decedent's blood concentrations of cefoperazone and sublactam were 0.368 and 0.143 ,g/ml respectively. As these concentrations were below concentrations reported after single dosing studies and below those considered to be minimally inhibitory, death was presumed to have been caused by hypersensitivity and not an overdose. In conclusion, this procedure is useful for detecting and quantitating cefoperazone and sublactam in postmortem blood and may be useful in the evaluation of anaphylaxis. [source] Development and validation of a liquid chromatographic/electrospray ionization mass spectrometric method for the quantitation of prazepam and its main metabolites in human plasmaJOURNAL OF MASS SPECTROMETRY (INCORP BIOLOGICAL MASS SPECTROMETRY), Issue 4 2005Paraskevi Valavani Abstract A method was developed and fully validated for the quantitation of prazepam and its major metabolites, oxazepam and nordiazepam, in human plasma. Sample pretreatment was achieved by solid-phase extraction using Oasis HLB cartridges. The extracts were analysed by high-performance liquid chromatography (HPLC) coupled with single-quadrupole mass spectrometry (MS) with an electrospray ionization interface. The MS system was operated in the selected ion monitoring mode. HPLC was performed isocratically on a reversed-phase XTerra MS C18 analytical column (150 × 3.0 mm i.d., particle size 5 µm). Diazepam was used as the internal standard for quantitation. The assay was linear over a concentration range of 5.0,1000 ng ml,1 for all compounds analyzed. The limit of quantitation was 5 ng ml,1 for all compounds. Quality control samples (5, 10, 300 and 1000 ng ml,1) in five replicates from three different runs of analysis demonstrated an intra-assay precision (CV) of ,9.1%, an inter-assay precision of ,6.0% and an overall accuracy (relative error) of <4.6%. The method can be used to quantify prazepam and its metabolites in human plasma covering a variety of pharmacokinetic or bioequivalence studies. Copyright © 2005 John Wiley & Sons, Ltd. [source] A validated liquid chromatographic/tandem mass spectrometric method for the determination of phencyclidine in microliter samples of rat serumJOURNAL OF MASS SPECTROMETRY (INCORP BIOLOGICAL MASS SPECTROMETRY), Issue 1 2005Howard P. Hendrickson Abstract A liquid chromatographic/tandem mass spectrometric method is described for the determination of phencyclidine (PCP) in small volumes of rat serum (e.g. 50 µl). Samples were extracted using a mixed-mode strong cation-exchange column and then separated isocratically using a narrow-bore (2.1 mm i.d.) 3 µm Hypersil phenyl column and a mobile phase consisting of an ammonium formate buffer (pH 2.7) with 60% (v/v) methanol. Detection was accomplished using positive ion electrospray ionization in the multiple reaction monitoring mode. Mass spectra were obtained and peaks were observed at an m/z (% abundance) of 244 (100), 159 (25), and 86 (89). Tandem mass spectra were also obtained from the m/z 244 precursor ion with peaks observed at m/z 159 (100), 86 (96), and 91 (11). Optimum serum PCP sensitivity and precision were obtained at a transition of m/z 244 , 159. Matrix-associated ion suppression did not significantly affect the accuracy (100,112%) or precision (CV ,8%) of the assay. The lower limit of quantitation was 1 ng ml,1 in 50 µl of serum. The method was used to study the serum pharmacokinetics of PCP in rats after an intravenous bolus dose of PCP. Copyright © 2004 John Wiley & Sons, Ltd. [source] Quantitative analysis of the P-glycoprotein inhibitor Elacridar (GF120918) in human and dog plasma using liquid chromatography with tandem mass spectrometric detectionJOURNAL OF MASS SPECTROMETRY (INCORP BIOLOGICAL MASS SPECTROMETRY), Issue 10 2004Ellen Stokvis Abstract A liquid chromatographic/tandem mass spectrometric (LC/MS/MS) method for the determination of the P-glycoprotein and breast cancer resistance protein inhibitor Elacridar in human and dog plasma is described. The internal standard was stable isotopically labelled Elacridar. Sample pretreatment involved liquid,liquid extraction with tert -butyl methyl ether. Analysis of Elacridar and internal standard was performed by reversed-phase LC on a basic stable minibore analytical column with an eluent consisting of acetonitrile and aqueous ammonia. An API-2000 triple-quadrupole mass spectrometer with an electrospray ion source was used in the positive-ion multiple reaction monitoring mode. The run time per sample was only 6 min. The method is sensitive and specific, with a dynamic range from 1 to 500 ng ml,1 from 100 µl of human or dog plasma. The accuracy of the method was within 15% bias and the precision was lower than 15% for all tested concentration levels and in both matrices. The method is simple and the liquid,liquid extraction produces clean samples. This method was successfully applied to support the pharmacokinetics of a clinical trial in which orally applied Elacridar was used as a bioavailability enhancer. Copyright © 2004 John Wiley & Sons, Ltd. [source] Screening, library-assisted identification and validated quantification of 23 benzodiazepines, flumazenil, zaleplone, zolpidem and zopiclone in plasma by liquid chromatography/mass spectrometry with atmospheric pressure chemical ionizationJOURNAL OF MASS SPECTROMETRY (INCORP BIOLOGICAL MASS SPECTROMETRY), Issue 8 2004Carsten Kratzsch Abstract A liquid chromatographic/mass spectrometric assay with atmospheric pressure chemical ionization (LC/APCI-MS) is presented for fast and reliable screening and identification and also for precise and sensitive quantification in plasma of the 23 benzodiazepines alprazolam, bromazepam, brotizolam, camazepam, chlordiazepoxide, clobazam, clonazepam, diazepam, flunitrazepam, flurazepam, desalkylflurazepam, lorazepam, lormetazepam, medazepam, metaclazepam, midazolam, nitrazepam, nordazepam, oxazepam, prazepam, temazepam and tetrazepam, triazolam, their antagonist flumazenil and the benzodiazepine BZ1 (omega 1) receptor agonists zaleplone, zolpidem and zopiclone. It allows confirmation of the diagnosis of an overdose situation and monitoring of psychiatric patients' compliance. The analytes were isolated from plasma using liquid,liquid extraction and were separated on a Merck LiChroCART column with Superspher 60 RP Select B as the stationary phase. Gradient elution was performed using aqueous ammonium formate and acetonitrile. After screening and identification in the scan mode using the authors' LC/MS library, the analytes were quantified in the selected-ion monitoring mode. The quantification assay was fully validated. It was found to be selective proved to be linear from sub-therapeutic to over therapeutic concentrations for all analytes, except bromazepam. The corresponding reference levels the assay's accuracy and precision data for all studied substances are listed. The accuracy and precision data were within the required limits with the exception of those for bromazepam. The analytes were stable in frozen plasma for at least 1 month. The validated assay was successfully applied to several authentic plasma samples from patients treated or intoxicated with various benzodiazepines or with zaleplone, zolpidem or zopiclone. It has proven to be appropriate for the isolation, separation, screening, identification and quantification of the drugs mentioned above in plasma for clinical toxicology, e.g. in cases of poisoning, and forensic toxicology, e.g. in cases of driving under the influence of drugs. Copyright © 2004 John Wiley & Sons, Ltd. [source] Simple, sensitive and rapid liquid chromatographic/electrospray ionization tandem mass spectrometric method for the quantification of lacidipine in human plasmaJOURNAL OF MASS SPECTROMETRY (INCORP BIOLOGICAL MASS SPECTROMETRY), Issue 7 2004N. V. S. Ramakrishna Abstract A simple, sensitive and rapid liquid chromatographic/electrospray ionization tandem mass spectrometric method was developed and validated for the quantification of lacidipine in human plasma using its structural analogue, amlodipine, as internal standard (IS). The method involves a simple single-step liquid,liquid extraction with tert -butyl methyl ether. The analyte was chromatographed on an Xterra MS C18 reversed-phase chromatographic column by isocratic elution with 20 mM ammonium acetate buffer,acetonitrile (10 : 90, v/v; pH 6) and analyzed by mass spectrometry in the multiple reaction monitoring mode. The precursor to product ion transitions of m/z 456.4 , 354.4 and m/z 409.3 , 238.3 were used to measure the analyte and the I.S., respectively. The chromatographic run time was 1.5 min and the weighted (1/x2) calibration curves were linear over the range 0.1,25 ng ml,1. Lacidipine was sensitive to temperature in addition to light. The method was validated in terms of accuracy, precision, absolute recovery, freeze,thaw stability, bench-top stability and re-injection reproducibility. The limit of detection and lower limit of quantification in human plasma were 50 and 100 pg ml,1, respectively. The within- and between-batch accuracy and precision were found to be well within acceptable limits (<15%). The analyte was stable after three freeze,thaw cycles (deviation <15%). The average absolute recoveries of lacidipine and amlodipine (IS) from spiked plasma samples were 51.1 ± 1.3 and 50.3 ± 4.9%, respectively. The assay method described here could be applied to study the pharmacokinetics of lacidipine. Copyright © 2004 John Wiley & Sons, Ltd. [source] Validated assay for quantification of oxcarbazepine and its active dihydro metabolite 10-hydroxycarbazepine in plasma by atmospheric pressure chemical ionization liquid chromatography/mass spectrometryJOURNAL OF MASS SPECTROMETRY (INCORP BIOLOGICAL MASS SPECTROMETRY), Issue 7 2002Hans H. Maurer Abstract Oxcarbazepine (OX), a new antiepileptic, may lead to unwanted side-effects or even life-threatening intoxications after overdose. Therefore, a validated liquid chromatographic/mass spectrometric (LC/MS) assay was developed for the quantification of OX and its pharmacologically active dihydro metabolite (dihydrooxcarbazepine, DOX, often named 10-hydroxycarbazepine). OX and DOX were extracted from plasma by the authors' standard liquid/liquid extraction and were separated on a Merck LiChroCART column with Superspher 60 RP Select B as the stationary phase. Gradient elution was performed using aqueous ammonium formate and acetonitrile. The compounds were quantified in the selected-ion monitoring mode using atmospheric pressure chemical ionization electrospray LC/MS. The assay was fully validated. It was found to be selective. The calibration curves were linear from 0.1 to 50 mg l,1 for OX and DOX. Limits of quantification were 0.1 mg l,1 for OX and DOX. The absolute recoveries were between 60 and 86%. The accuracy and precision data were within the required limits. The analytes in frozen plasma samples were stable for at least 1 month. The method was successfully applied to several authentic plasma samples from patients treated or intoxicated with OX. The measured therapeutic plasma levels ranged from 1 to 2 mg l,1 for OX and from 10 to 40 mg l,1 for DOX. The validated LC/MS assay proved to be appropriate for quantification of OX and DOX in plasma for clinical toxicology and therapeutic drug monitoring purposes. The assay is part of a general analysis procedure for the isolation, separation and quantification of various drugs and for their full-scan screening and identification. Copyright © 2002 John Wiley & Sons, Ltd. [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] Identification and determination of the saikosaponins in Radix bupleuri by accelerated solvent extraction combined with rapid-resolution LC-MSJOURNAL OF SEPARATION SCIENCE, JSS, Issue 13 2010Yun-Yun Yang Abstract A method based on accelerated solvent extraction combined with rapid-resolution LC,MS for efficient extraction, rapid separation, online identification and accurate determination of the saikosaponins (SSs) in Radix bupleuri (RB) was developed. The RB samples were extracted by accelerated solvent extraction using 70% aqueous ethanol v/v as solvent, at a temperature of 120°C and pressure of 100,bar, with 10,min of static extraction time and three extraction cycles. Rapid-resolution LC separation was performed by using a C18 column at gradient elution of water (containing 0.5% formic acid) and acetonitrile, and the major constituents were well separated within 20,min. A TOF-MS and an IT-MS were used for online identification of the major constituents, and 27 SSs were identified or tentatively identified. Five major bioactive SSs (SSa, SSc, SSd, 6,- O -acetyl-SSa and 6,- O -acetyl-SSd) with obvious peak areas and good resolution were chosen as benchmark substances, and a triple quadrupole MS operating in multiple-reaction monitoring mode was used for their quantitative analysis. A total of 16 RB samples from different regions of China were analyzed. The results indicated that the method was rapid, efficient, accurate and suitable for use in the quality control of RB. [source] Simultaneous determination of 103 pesticide residues in tea samples by LC-MS/MSJOURNAL OF SEPARATION SCIENCE, JSS, Issue 9 2009Zhiqiang Huang Abstract A simple and sensitive method was developed and validated for the simultaneous determination of 103 pesticide residues in tea by LC-MS/MS. For the analysis of the pesticide with polarity, thermal lability or low volatility, this LC-MS/MS method has an advantage over GC. In this work, residual pesticides were extracted from the tea sample with ACN and then purified using Carb-NH2 SPE cartridges. Using the multiple reaction monitoring mode, the pesticides were quantified and identified by the most abundant and characteristic fragment ions. The recoveries obtained for each pesticide ranged between 65 and 114% at three spiked concentration levels. The intra-day precisions were lower than 19.6%. Good linear relationships were observed with the correlation coefficients r2 >0.996 for all analytes. The established method was successfully applied to the determination of pesticide residues in real tea samples. [source] Rapid simultaneous determination of codeine and morphine in plasma using LC-ESI-MS/MS: Application to a clinical pharmacokinetic studyJOURNAL OF SEPARATION SCIENCE, JSS, Issue 2 2009Qiongfeng Liao Abstract A rapid and sensitive high-performance LC-MS/MS method was developed and validated for the simultaneous quantification of codeine and its metabolite morphine in human plasma using donepezil as an internal standard (IS). Following a single liquid-liquid extraction with ethyl acetate, the analytes were separated using an isocratic mobile phase on a C18 column and analyzed by MS/MS in the selected reaction monitoring mode using the respective [M+H]+ ions, mass-to-charge ratio (m/z) 300/165 for codeine, m/z 286/165 for morphine and m/z 380/91 for IS. The method exhibited a linear dynamic range of 0.2,100/0.5,250 ng/mL for codeine/morphine in human plasma, respectively. The lower LOQs were 0.2 and 0.5 ng/mL for codeine and its metabolite morphine using 0.5 mL of human plasma. Acceptable precision and accuracy were obtained for concentrations over the standard curve range. A run time of 2.0 min for each sample made it possible to analyze more than 300 human plasma samples per day. The validated LC-MS/MS method was applied to a pharmacokinetic study in which healthy Chinese volunteers each received a single oral dose of 30 mg codeine phosphate. [source] Quantification of Greenland halibut serum vitellogenin: a trip from the deep sea to the mass spectrometerRAPID COMMUNICATIONS IN MASS SPECTROMETRY, Issue 7 2009Alejandro M. Cohen This paper focuses on the sequential steps involved in developing a technique for quantifying Greenland halibut vitellogenin, a serum protein biomarker, using a comprehensive mass spectrometric approach. In the first phase of this study, in-gel trypsin digestions of serum proteins separated by sodium dodecyl sulphate polyacrylamide gel electrophoresis (SDS-PAGE) were analyzed by matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS). A characteristic band around a molecular mass of 185,kDa, present in the mature female specimens, but absent in the male samples, was identified as vitellognin according to the peptide mass fingerprint obtained by MALDI-MS. Subsequently, MALDI and electrospray ionization tandem mass spectrometry (ESI-MS/MS) analyses were performed on the digest of the vitellogenin band for de novo sequencing. From these studies, a characteristic 'signature' peptide (sequence: FFGQEIAFANIDK) was selected from a list of candidate peptides as a surrogate analytical standard used for quantification purposes. Sample preparation for vitellogenin quantification consisted of a simple one-step overnight trypsin digestion. Samples were spiked with an isotopologue signature peptide standard and analyzed by high-performance liquid chromatography (HPLC) coupled in-line to an electrospray quadrupole-hexapole-quadrupole tandem mass spectrometer, operated in selective reaction monitoring mode. Transitions [(m/z 750.0,,,1020.4 and 750.0,,,1205.4) and (754.8,,,1028.6 and 754.8,,,1213.2)] were monitored for the signature peptide and the internal standard, respectively. Samples obtained from the field showed that vitellogenin levels were in accordance with fish maturity determined by macroscopic examination of the gonad, proving this technique suitable for measuring vitellogenin as a serum protein biomarker for reproductive maturity in female fish. Copyright © 2009 John Wiley & Sons, Ltd. [source] Liquid chromatography/tandem triple-quadrupole mass spectrometry for determination of paclitaxel in rat tissuesRAPID COMMUNICATIONS IN MASS SPECTROMETRY, Issue 12 2006Xinyong Tong A liquid chromatography/tandem triple-quadrupole mass spectrometry assay to quantify paclitaxel in rat tissue homogenates containing taxol or paclitaxel nanoliposome (PTX-NLP) was developed and validated. Liquid-liquid extraction with tert -butyl methyl ether was used for tissue sample preparation and docetaxel was used as the internal standard. Paclitaxel and docetaxel were separated on a 200,mm,×,4.6,mm,×,5,µm C18 column and quantified using a triple-quadrupole mass spectrometer operating in positive ion electrospray selective reaction monitoring mode (ESI+ -SRM) with a total run time of 6.0,min. The peak area of the m/z 876.3,,,307.9 transition of paclitaxel is measured versus that of the m/z 830.3,,,549.1 transition of docetaxel to generate the standard curves. The standard curves were linear over the concentration range of 0.2008,2008,ng/mL for different tissues. The method had high extraction recovery (>90%) and accuracy (>90%) with the intra-day and inter-day precision <15%. Frozen stability, freeze/thaw stability, extraction stability and solution stability at ambient temperature were examined, which indicated the tissue samples should be extracted within 5 days and avoid being frozen and thawed repeatedly over 5 times. Extracted samples after evaporation could be stored at ,20°C for 20 days without drug degradation and no degradation was also observed after solution samples were left to stand at ambient temperature for 24,h. This assay was used to support an in vivo biodistribution study of PTX-NLP in rats. Copyright © 2006 John Wiley & Sons, Ltd. [source] Development of a multi-residue method for the determination of 18 carbamates in tobacco by high-performance liquid chromatography/positive electrospray ionisation tandem mass spectrometryRAPID COMMUNICATIONS IN MASS SPECTROMETRY, Issue 4 2006B. Mayer-Helm A multi-residue method for the determination of carbamates in tobacco was developed by high-performance liquid chromatography (HPLC) triple quadrupole mass spectrometry (MS). A rapid sample preparation consisted of an extraction step with methanol, centrifugation and 1:1 dilution with aqueous 10,mM ammonium acetate. After filtration these extracts were directly analysed by reversed-phase HPLC coupled to positive electrospray ionisation tandem mass spectrometry operated in the multiple reaction monitoring mode. Capillary voltage and dwell times were optimised to reduce matrix effects and to increase sensitivity. The method was validated for the determination of 18 carbamates in three main types of raw tobacco and three tobacco products. The interday accuracy ranged between 80 and 110% with a relative standard deviation (RSD) of <30%. The limits of quantification (LOQs) ranged between 0.01 and 0.04,ppm for almost all carbamates, except aldicarb sulfone, carbofuran, and pebulate, with LOQs between 0.10 and 0.20,ppm. These LOQs were clearly below the guidance residue levels defined by the Agrochemical Advisory Committee of CORESTA, an association of organisations having scientific research relative to tobacco. Copyright © 2006 John Wiley & Sons, Ltd. [source] Semi-automated quantification of ivermectin in rat and human plasma using protein precipitation and filtration with liquid chromatography/tandem mass spectrometryRAPID COMMUNICATIONS IN MASS SPECTROMETRY, Issue 12 2004Tony Pereira Ivermectin is a parasiticide commonly used in humans and livestock. It is currently under development for the treatment of pediculosis of humans (head lice) that does not respond to established treatments. A liquid chromatography/turbo ion spray tandem mass spectrometry (LC/TIS-MS/MS) method for the determination of ivermectin in rat and human plasma has been developed that uses emamectin [4,-epi-(methylamino)-4,-deoxyavermectin] as the internal standard. Sample preparation involved protein precipitation and filtration of fortified plasma in the 96-well format. Chromatographic separation was accomplished using fast gradient conditions on a C8 stationary phase. The analytes were detected with the mass spectrometer operated in the positive ion, multiple reaction monitoring mode. The method exhibited good intra- and interday accuracy and precision, and was linear over a dynamic range of 1,2000,ng/mL. In rat plasma, intraday accuracy ranged between 84,93% for the low quality control (QC) sample (1.5 ng/mL), and between 91,109% for the remaining QCs. Intraday precision ranged between 4.9,15% for the low QC, and 0.8,6.3% for the remaining QCs. Interday accuracy ranged between 88,107%, and precision between 4.1,11%. Similar data was obtained using human plasma. An investigation of matrix effects indicated that the ionization efficiency of ivermectin was favored by the presence of an ammonium ion in an aqueous environment. The implications of this observation toward assay sensitivity are discussed. Copyright © 2004 John Wiley & Sons, Ltd. [source] Quantification of arecoline (areca nut alkaloid) in neonatal biological matrices by high-performance liquid chromatography/electrospray quadrupole mass spectrometryRAPID COMMUNICATIONS IN MASS SPECTROMETRY, Issue 17 2003Simona Pichini A high-performance liquid chromatography (HPLC) method with mass spectrometric detection is described for determination of arecoline in newborn meconium, urine and cord serum, using pilocarpine as internal standard. The analytes were extracted from neonatal biological matrices with chloroform/isopropanol (95:5, v/v) at alkaline pH. Extracts were analyzed by HPLC coupled to an electrospray (ESI) interface and a quadrupole mass spectrometer. Chromatography was performed on a C8 reversed-phase column using 10 mM ammonium acetate (pH 4.3)/acetonitrile (90:10, v/v) as mobile phase. The mass spectrometer was operated in selected ion monitoring mode. The method was validated over the concentration range 0.005,1.00,,g/g meconium, 0.004,1.00,,g/mL cord serum and 0.001,1.00,,g/mL urine. Mean recoveries ranged between 86.5 and 90.7% for arecoline in the different biological matrices, with precision always better than 10%. The quantification limits of arecoline were 0.005,,g/g meconium, 0.004,,g/mL cord serum, and 0.001,,g/mL urine. The method was applied to the analysis of neonatal biological matrices to assess eventual fetal exposition to arecoline. Two newborns from Asian mothers who declared areca nut consumption presented arecoline in meconium with concentrations in the range 0.006,0.008,,g/g; also the urine from one neonate tested positive for the drug. Copyright © 2003 John Wiley & Sons, Ltd. [source] Liquid chromatography/tandem mass spectrometry for the identification and determination of trichothecenes in maizeRAPID COMMUNICATIONS IN MASS SPECTROMETRY, Issue 10 2003Aldo Laganà A reliable, sensitive and selective liquid chromatography/tandem mass spectrometry (LC/MS/MS) method has been developed to determine four trichothecene mycotoxins (nivalenol, deoxynivalenol, fusarenon X and 3-acetyldeoxynivalenol) in maize. Sample preparation was performed by extracting the analytes with a mixture of acetonitrile and water, followed by a solid-phase extraction with Carbograph-4 cartridges as the purification step. For the LC/MS/MS analysis two interfacing systems, Turbo IonSpray (TISP) and atmospheric pressure chemical ionization (APCI), were compared in both negative and positive ion modes. LC and MS parameters were optimized to achieve better results and sensitivity. The effect of mobile phase modifiers such as ammonium acetate and formic acid on the ionization yield was also evaluated. The best results were obtained using the electrospray ionization (ESI) interface in negative ion mode and the multiple reaction monitoring mode (MRM) for the quantitation. The detection limits ranged between 10,ng/g for fusarenon X and 1.5,ng/g for deoxynivalenol. A linear working range was achieved with a standard deviation between 3 and 10% and recovery rates from the maize samples above 81%. The procedure was applied to the analysis of a set of maize samples collected from farms located in different areas of northern and central Italy. The investigated samples turned out to be contaminated primarily with deoxynivalenol and, to a minor extent, with its derivatives. Copyright © 2003 John Wiley & Sons, Ltd. [source] Quantitative assay of plasma homocysteine thiolactone by gas chromatography/mass spectrometryRAPID COMMUNICATIONS IN MASS SPECTROMETRY, Issue 4 2003Parham Daneshvar Enzymatic cyclization of homocysteine forms a reactive thiolactone that may play an important role in its cardiovascular toxicity, but reliable quantitation of the free thiolactone metabolite in physiological fluids has not been reported. We have therefore used a highly selective gas chromatography/mass spectrometry (GC/MS) technique combined with the sensitivity of negative chemical ionization (NCI) to develop a quantitative method for the detection of homocysteine thiolactone (HcyTL) in plasma. To improve accutacy the deuterated isomer d4 -HcyTL was synthesized and added to plasma as internal standard. The plasma was then treated with silica solid-phase extraction and derivatized with heptafluorobutyric anhydride. The derivative was analyzed by GC/MS in NCI mode with methane as the reagent gas and quantified by analyzing for the HcyTL ion [M, HF] and its d4 -HcyTL counterpart in single-ion monitoring mode. The calibration curve showed a dynamic linear range up to 40 nmol/L. Within-day precision (n,=,20, nominal concentration 5.2 nmol/L) was 0.96% and between-day precision was 3.9%, with a detection limit of 1.7 nmol/L and quantification limit of 5.2 nmol/L. Two human plasma samples had HcyTL concentrations of 18 and 25 nmol/L. This facile method for quantitation of homocysteine thiolactone opens the way for more detailed clinical studies of its potential role in homocysteine-induced arteriosclerosis and vaso-occlusive disease. Copyright © 2003 John Wiley & Sons, Ltd. [source] Quantitative determination of perfluorooctanoic acid ammonium salt in human serum by high-performance liquid chromatography with atmospheric pressure chemical ionization tandem mass spectrometryRAPID COMMUNICATIONS IN MASS SPECTROMETRY, Issue 7 2002Cristina Sottani A sensitive, specific, accurate and reproducible analytical method was developed and validated to quantify perfluorooctanoic acid (PFOA) in human serum. After initial extraction with an ion-paring reagent, the procedure for quantifying PFOA is based on high-performance liquid chromatography (HPLC) interfaced to negative ion tandem mass spectrometry, operating in selected ion monitoring mode. The retention times of PFOA and its internal standard (D,L-malic acid) were 5.85 and 1.70,min, respectively. The assay was linear over the range 0,500,ng/mL, with a lower limit of quantification (LOQ) of 25,ng/mL, and with a coefficient of variation (CV) of 7.3%. The lower limit of detection (LOD) was assessed as 10,ng/mL. The overall precision and accuracy were assessed on three different days. The within- and between-day precision was ,9.7 and 6.8%, respectively, and the accuracy was in the range 96,114%. The mean extracted recovery assessed at three different concentrations (100, 250, and 500,ng/mL) was always more than 85%. With this method no derivatization procedure was needed, thus avoiding possible thermal and chemical decomposition reactions of PFOA. The assay was applied to quantify perfluorooctanoic acid in serum from employees exposed to fluorochemicals commonly used in industrial applications for polymer production. The quantitative results for PFOA blood levels were found to vary between 100 and 982,ng/mL. Copyright © 2002 John Wiley & Sons, Ltd. [source] High-performance liquid chromatography/tandem mass spectrometry for the quantitative analysis of a novel taxane derivative (BAY59-8862) in biological samples and characterisation of its metabolic profile in rat bile samplesRAPID COMMUNICATIONS IN MASS SPECTROMETRY, Issue 19 2001Cristina Sottani A sensitive, specific, accurate and reproducible high-performance liquid chromatography (HPLC) analytical method was developed and validated for the quantification of the novel oral taxane analogue BAY59-8862 in mouse plasma and tissue samples. A fully automated solid-phase extraction procedure was applied to the plasma after internal standard (IS) addition, with only 0.2,mL volume of the sample loaded on a CN-Sep-pak cartridge. In the case of the tissues a very simple acetonitrile extraction was used to recover BAY59-8862 and its internal standard from liver. The procedure for the quantification of BAY59-8862 and its IS (IDN5127) is based on high-performance liquid chromatography/ion spray-tandem mass spectrometry, operating in selected ion monitoring mode. The retention times of BAY and IS were 7.21 and 10.36,min, respectively. In both plasma and tissue specimens the assay was linear in the range 50,5000,ng/mL (ng/g). The overall precision and accuracy were assessed on three different days. The results for plasma were within 6.1% (precision) and between 99 and 112% (accuracy), and for the liver samples within 7.3% and between 104 and 118%, respectively. The LOD was 5,ng/mL and 20,ng/g in the plasma and liver, respectively. In addition, the biliary excretion of the compound in rats was studied. The study showed that an oxidative chemical reaction was the preferred metabolic pathway for biliary excretion, and two sets of mono- and dihydroxylated metabolites were detected by LC/ISP-MS/MS experiments. With this method, BAY59-8862 pharmacokinetic was determined in mice. The combined results demonstrate that the methodology can be considered a valid approach to conduct pharmacokinetic and metabolic studies during preclinical and clinical investigations. Copyright © 2001 John7 Wiley & Sons, Ltd. [source] Multiresidue analysis of tranquilizers and the beta-blocker Carazolol in meat by liquid chromatography/tandem mass spectrometryRAPID COMMUNICATIONS IN MASS SPECTROMETRY, Issue 18 2001Anton Kaufmann A fast and simple method for the quantification of a number of tranquilizers and the beta-blocker Carazolol in pork and bovine kidney is described. Extracts are purified/concentrated by a solid phase extraction step and separated on a reversed phase column with an alkaline (ammonia) acetonitrile gradient. The electrospray tandem mass spectrometer is operated in positive ion multireaction monitoring mode. Resulting chromatograms are free of interfering peaks. The recovery is >75% for all analytes and the limit of detection <1 ppb, which is well below the current maximum residue limit for the various compounds. Copyright © 2001 John Wiley & Sons, Ltd. [source] Liquid chromatography tandem mass spectrometry method for determination of bisoprolol in human plasma using d5-bisoprolol as the internal standardBIOMEDICAL CHROMATOGRAPHY, Issue 6 2010Gang-yi Liu Abstract A simple, reliable and sensitive liquid chromatography tandem mass spectrometry (LC-MS/MS) protocol was developed and validated for quantification of bisoprolol in human plasma. The sample was pretreated with a simple procedure of protein precipitation and an isotope-labeled d5-bisoprolol was used as internal standard. The chromatographic separation was performed on a Capcell Pak C18 MG III column (100,mm × 2.0,mm, 5,µm). The protonated ion of the analyte was detected in positive ionization by multiple reaction monitoring mode. The mass transition pairs of m/z 326.3 , 116.3 and m/z 331.3 , 121.3 were used to detect bisoprolol and the internal standard, respectively. Linearity, accuracy, precision, recovery, matrix effect, dilution test and stability were evaluated during method validation over the range of 0.5,100,ng/mL. The validated method was successfully applied to analyze human plasma samples in a bisoprolol bioavailability study. Copyright © 2009 John Wiley & Sons, Ltd. [source] Determination of asperosaponin VI in rat plasma by HPLC-ESI-MS and its application to preliminary pharmacokinetic studiesBIOMEDICAL CHROMATOGRAPHY, Issue 5 2010Kai Li Abstract Asperosaponin VI (also named akebia saponin D) is a typical bioactive triterpenoid saponin isolated from the rhizome of Dipsacus asper Wall (Dipsacaceae). In this work, a sensitive high-performance liquid chromatography,electrospray ionization,mass spectrometry (HPLC-ESI-MS) assay has been established for determination of asperosaponin VI in rat plasma. With losartan as the internal standard (IS), plasma samples were prepared by protein precipitation with methanol. Chromatographic separation was performed on a C18 column with a mobile phase of 10,mm ammonium acetate buffer containing 0.05% formic acid,methanol (32,:,68, v/v). The analysis was performed on an ESI in the selected ion monitoring mode using target ions at m/z 951.4 for asperosaponin VI and m/z 423.2 for the IS. The calibration curve was linear over the range 3,1000,ng/mL and the lower limit of quantification was 3.0,ng/mL. The intra- and inter-assay variability values were less than 9.5 and 7.8%, respectively. The accuracies determined at the concentrations of 3.0, 100.0, 300.0 and 1000,ng/mL for asperosaponin VI were within ±15.0%. The validated method was successfully applied to a pharmacokinetic study in rats after oral administration of asperosaponin VI. Copyright © 2009 John Wiley & Sons, Ltd. [source] A sensitive liquid chromatography,electrospray ionization,mass spectrometry method for the simultaneous determination of pentoxyverine citrate and guaifenesin in human plasma,application to pharmacokinetic and bioequivalence studiesBIOMEDICAL CHROMATOGRAPHY, Issue 4 2010Jinhua Wen Abstract A sensitive and specific liquid chromatography,electrospray ionization,mass spectrometry method for the identification and quantification of pentoxyverine citrate and guaifenesin in human plasma has been developed. After extraction from plasma samples by ethyl acetate, the internal standard and analytes were separated by high-performance liquid chromatographic on a Shim-pack VP-ODS C18 column (150 × 2.0 mm) using a mobile phase consisting of A (methanol) and B (0.4% glacial acetic acid and 4 mmol/L ammonium acetate) (A:B, 43 : 57). Analysis was performed on a Shimadzu LC/MS-2010A in selected ion monitoring mode with a positive electrospray ionization interface. The method was linear in the concentration range of 1.0,640.0 ng/mL for pentoxyverine citrate and 0.025,6.4 ,g/mL for guaifenesin. The inter- and intra- precision were all within 12% and accuracy ranged from 85 to 115%. The lower limits of quantification were 1.0 ng/mL for pentoxyverine citrate and 25.0 ng/mL for guaifenesin. The extraction recovery was on average 81.95% for pentoxyverine citrate and 89.03% for guaifenesin. This is the first assay method reported for the simultaneous determination of pentoxyverine citrate and guaifenesin in plasma using one chromatographic run. Copyright © 2009 John Wiley & Sons, Ltd. [source] Quantitative determination of dipyridamole in human plasma by high-performance liquid chromatography,tandem mass spectrometry and its application to a pharmacokinetic studyBIOMEDICAL CHROMATOGRAPHY, Issue 3 2010Ting Qin Abstract Dipyridamole is a classic platelet inhibitor which has been a key medicine in clinical therapy of thrombosis and cerebrovascular disease. A rapid, selective and convenient method using high-performance liquid chromatography,tandem mass spectrometry (HPLC-MS/MS) was developed for determination of dipyridamole in human plasma. After protein precipitation of 200 ,L plasma with methanol, dipyridamole and diazepam (internal standard) were chromatographed on an UltimateÔ XB-C18 (50 × 2.1 mm i.d, 3 ,) column with the mobile phase consisting of methanol,ammonium acetate (5 mM; 80 : 20, v/v) at a flow rate of 0.25 mL/min. The detection was performed on a triple quadrupole tandem mass spectrometer by multiple reaction monitoring mode via positive eletrospray ionization source (ESI+). The retention times of dipyridamole and diazepam were 1.4 and 1.2 min, respectively. The method was validated over a concentration range of 0.0180,4.50 ,g/mL (r2 , 0.99) with a lower limit of quantitation (LLOQ) of 0.0180 ,g/mL for dipyridamole. The intra- and inter-day precisions (RSD) of the assay at all three QC levels were 1.6,12.7% with an accuracy (RE) of ,4.3,1.9%, which meets the requirements of the FDA guidance. The HPLC-MS/MS method herein described was proved to be suitable for pharmacokinetic study of sustained-release dipyridamole tablet in volunteers after oral administration. Copyright © 2009 John Wiley & Sons, Ltd. [source] A liquid chromatography/tandem mass spectrometry method for determination of aristolochic acid-I in rat plasmaBIOMEDICAL CHROMATOGRAPHY, Issue 2 2010Yiming Liu Abstract A sensitive, rapid and specific liquid chromatography,electrospray ionization,tandem mass spectrometry method was developed and validated for the determination of aristolochic acid-I (AA-I) in rat plasma. Finasteride was used as the internal standard (IS). The analyte was separated on a Zorbax Eclipse XDB-C18 column by isocratic elution with methanol-10,mM ammonium acetate (75:25, v/v, pH = 7.3) at a flow rate of 0.25,mL/min, and analyzed by mass spectrometry in positive multiple reaction monitoring mode. The precursor-to-product ion transitions of m/z 359.0 , 298.2 and m/z 373.1 , 305.2 were used to detect AA-I and IS, respectively. Good linearity was achieved over a range of 0.4,600,ng/mL. Intra- and inter-day precisions measured as relative standard deviation were less than 13.5%, and accuracy ranged from 94.2 to 97.5%. The developed method was successfully applied in the pharmacokinetic study of AA-I in rats. Copyright © 2009 John Wiley & Sons, Ltd. [source] Solid-phase extraction and analysis of paroxetine in human plasma by ultra performance liquid chromatography,electrospray ionization mass spectrometryBIOMEDICAL CHROMATOGRAPHY, Issue 2 2010Mitesh Bhatt Abstract A rapid, sensitive and rugged solid-phase extraction ultra performance liquid chromatography tandem mass spectrometry (UPLC-MS/MS) method was developed for determination of paroxetine in human plasma. The procedure for sample preparation includes simple SPE extraction procedure coupled with Hypersil Gold C18 column (100 mm , 2.1 mm, i.d., 1.9 ,m) with isocratic elution at a flow-rate of 0.350 mL/min and fluoxetine was used as the internal standard. The analysis was performed on a triple-quadrupole tandem mass spectrometer by multiple reactions monitoring mode via electrospray ionization. Using 500 ,L plasma, the methods were validated over the concentration range 0.050,16.710 ng/mL for paroxetine, with a lower limit of quantification of 0.050 ng/mL. The intra- and inter-day precision and accuracy of the quality control samples were within 10.0%. The recovery was 69.2 and 74.4% for paroxetine and fluoxetine respectively. Total run time was only 1.9 min. The method was highly reproducible and gave peaks with excellent chromatography properties. Copyright © 2009 John Wiley & Sons, Ltd. [source] Rapid quantification of levosulpiride in human plasma using RP-HPLC-MS/MS for pharmacokinetic and bioequivalence studyBIOMEDICAL CHROMATOGRAPHY, Issue 12 2009Jin-Hee Park Abstract A rapid and validated method for analysis of levosulpiride in human plasma using liquid chromatography coupled to tandem mass spectrometry was developed. Levosulpiride and tiapride (IS, internal standard) were extracted from alkalized plasma samples with ethylacetate and separation by RP-HPLC. Detection was performed by positive ion electrospray ionization in multiple-reaction monitoring mode, monitoring the transitions m/z 342.1 , m/z 112.2 and m/z 329.1 , m/z 213.2, for quantification of levosulpiride and IS, respectively. The standard calibration curves showed good linearity within the range of 2,200 ng/mL (r2 , 0.9990). The lower limit of quantitation was 2 ng/mL. The retention times of levosulpiride (0.63 min) and IS (0.66 min) presented a significant time saving benefit of the proposed method. No significant metabolic compounds were found to interfere with the analysis. This method offered good precision and accuracy and was successfully applied for the pharmacokinetic and bioequivalence study of a 25 mg of levosulpiride tablet in 24 healthy Korean volunteers. Copyright © 2009 John Wiley & Sons, Ltd. [source] Determination of teniposide in rat plasma by ultra performance liquid chromatography electrospray ionization tandem mass spectrometry after intravenous administrationBIOMEDICAL CHROMATOGRAPHY, Issue 9 2009Jing Wang Abstract A novel, specific and rapid ultra performance liquid chromatography electrospray ionization tandem mass spectrometry method has been developed and validated for determination of teniposide in rat plasma. A one-step liquid,liquid extraction method was used and the separation was carried out on an Acquity UPLCTM BEH C18 column with gradient elution using a mobile phase composed of acetonitrile and water (containing 0.1% formic acid) at a flow rate of 0.20 mL/min. A triple quadrupole tandem mass spectrometer in multiple-reaction monitoring mode via an electrospray ionization interface was used for the detection of teniposide. The detection was complete within 3.0 min. A linear calibration curve was obtained over the concentration range 10,10,000 ng/mL for teniposide, with a lower limit of quantification of 10 ng/mL. The intra-day precision and inter-day precision (relative standard deviation) were less than 10.23 and 13.09%, respectively. The developed method was applied for the first time to the pharmacokinetic study of teniposide in rats following a single intravenous administration of 4.5 mg/kg teniposide. Copyright © 2009 John Wiley & Sons, Ltd. [source] | ||||||||||