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Chromatography Mass Spectrometry (chromatography + mass_spectrometry)
Kinds of Chromatography Mass Spectrometry Selected AbstractsAnalysis of the Volatile Components in the Leaves of Cinnamomum camphora by Static Headspace Gas Chromatography Mass Spectrometry Combined with Accurate Weight MeasurementCHINESE JOURNAL OF CHEMISTRY, Issue 8 2010Fengjun Zhu Abstract The volatile components in the leaves of C. camphora were analyzed by static headspace-gas chromatography/mass spectrometry (HS-GC-MS) combined with accurate weight measurement. Accurate weight measurement obtained by Time-of-Flight mass spectrometry (TOF-MS) helped to confirm the identification of volatiles in the analysis. 59 volatile components in the leaves of C. camphora were identified, which mainly included cis -3-hexen-1-ol (5.6%), 3-hexen-1-ol, acetate (Z) (11.1%), , -caryophyllene (15.4%), bicyclogermarene (8.4%), trans -nerolidol (19.5%) and 9-oxofarnesol (7.7%). The results show that method using HS-GC-MS combined with accurate weight measurement achieves reliable identification and has extensive application in the analysis of volatile components present in complex samples. [source] Evaluation of a sunscreen photoprotective effect by ascorbic acid assessment in human dermis using microdialysis and gas chromatography mass spectrometryEXPERIMENTAL DERMATOLOGY, Issue 3 2005Nathalie Lévêque Abstract:, Ultraviolet irradiation causes adverse effects like sunburn, photosensitivity reactions or immunologic suppression. The aim of this study was to evaluate the photo-protective outcome of a sunscreen cream (SPF8) by the determination of erythema indexes and the assessment of ascorbic acid and its metabolites in human dermis. These substances were used as markers of oxidative effect. Eight healthy female subjects were enrolled in this study. Two abdominal areas were exposed to solar simulated irradiation with three minimal erythema dose, one with SPF8 application and the other site without SPF8 application. Two other areas were used as control, one without SPF8 application and the other site after SPF8 application. Ascorbic acid and its metabolites (dehydroascorbic acid, threonic acid, oxalic acid and xylose) were collected from human dermis by microdialysis and assessed by gas chromatography mass spectrometry. Irradiated site without sunscreen application had significantly demonstrated lower dermis ascorbic acid concentrations and a higher erythema index than the three other sites (P < 0.05). Threonic acid, oxalic acid and xylose dermis concentrations were significantly higher in site III than in the control site I (P < 0.05). The protected-irradiated site did not show erythema formation and there was stability of ascorbic acid dermis concentrations with non-variation in its metabolites. The assessment of ascorbic acid and its metabolites in human dermis could be an efficient tool to demonstrate the oxidative process and consequently to control the efficiency of sunscreen creams against undesirable UV effects. [source] A pilot study into the chemical and sensorial effect of thyme and pennyroyal essential oil on hens eggsINTERNATIONAL JOURNAL OF FOOD SCIENCE & TECHNOLOGY, Issue 9 2009Tegan J. Smith Summary Previously, it has been shown that thyme and pennyroyal essential oils have potential as acaricides against the poultry red mite Dermanyssus gallinae. The effect of these oils on the occurrence of taint in hens' eggs was investigated using in vitro immersion tests and in vivo methods where poultry huts containing laying hens were sprayed weekly with oil. Analysis of extracts from eggs by gas chromatography mass spectrometry (GCMS) showed that no detectable taint was present in hens' eggs. However, consumer sniff tests, although restricted and only preliminary in nature, showed a significant negative response to the smell of both unbroken and cracked open eggs between those taken from poultry huts treated with pennyroyal essential oil and all other eggs tested. Some essential oils, such as thyme, may be more suitable as an acaracidal product than others, such as pennyroyal, for the use within a commercial poultry system for laying hens. [source] Cellular/intramuscular myxoma and grade I myxofibrosarcoma are characterized by distinct genetic alterations and specific composition of their extracellular matrixJOURNAL OF CELLULAR AND MOLECULAR MEDICINE, Issue 7 2009Stefan M. Willems Abstract Cellular myxoma and grade I myxofibrosarcoma are mesenchymal tumours that are characterized by their abundant myxoid extracellular matrix (ECM). Despite their histological overlap, they differ clinically. Diagnosis is therefore difficult though important. We investigated their (cyto) genetics and ECM. GNAS1 -activating mutations have been described in intramuscular myxoma, and lead to downstream activation of cFos. KRAS and TP53 mutations are commonly involved in sarcomagenesis whereby KRAS subsequently activates c-Fos. A well-documented series of intramuscular myxoma (three typical cases and seven cases of the more challenging cellular variant) and grade I myxofibrosarcoma (n= 10) cases were karyotyped, analyzed for GNAS1, KRAS and TP53 mutations and downstream activation of c-Fos mRNA and protein expression. ECM was studied by liquid chromatography mass spectrometry and expression of proteins identified was validated by immunohistochemistry and qPCR. Grade I myxofibrosarcoma showed variable, non-specific cyto-genetic aberrations in 83,5% of cases (n= 6) whereas karyotypes of intramuscular myxoma were all normal (n= 7). GNAS1 -activating mutations were exclusively found in 50% of intramuscular myxoma. Both tumour types showed over-expression of c-Fos mRNA and protein. No mutations in KRAS codon 12/13 or in TP53 were detected. Liquid chromatography mass spectrometry revealed structural proteins (collagen types I, VI, XII, XIV and decorin) in grade I myxofibrosarcoma lacking in intramuscular myxoma. This was confirmed by immunohistochemistry and qPCR. Intramuscular/cellular myxoma and grade I myxofibrosarcoma show different molecular genetic aberrations and different composition of their ECM that probably contribute to their diverse clinical behaviour. GNAS1 mutation analysis can be helpful to distinguish intramuscular myxoma from grade I myxofibrosarcoma in selected cases. [source] Evaluation of the evidential value of physicochemical data by a Bayesian network approachJOURNAL OF CHEMOMETRICS, Issue 7-8 2010Grzegorz Zadora Abstract The growing interest in applications of Bayesian networks (BNs) in forensic science raises the question of whether BN could be used in forensic practice for the evaluation of results from physicochemical analysis of a limited number of observations from flammable liquids (weathered kerosene and diesel fuel) by automated thermal desorption gas chromatography mass spectrometry (ATD-GC/MS), car paints by pyrolysis gas chromatography mass spectrometry (Py-GC/MS) and fibres by microspectrophotometry (MSP) in the visible (VIS) range. Therefore, various simple BN models, which allow the evaluation of both discrete and continuous types of data, were studied in order to address questions raised by the representatives of the administration of justice, concerning the identification and classification of objects into certain categories and/or the association between two items. The results of the evaluation performed by BN models were expressed in the form of a likelihood ratio, which is a well-documented measure of evidential value in the forensic field. From the results obtained, it can be concluded that BN models seem to be promising tool for evaluating physicochemical data. Copyright © 2010 John Wiley & Sons, Ltd. [source] Classification of GC-MS measurements of wines by combining data dimension reduction and variable selection techniquesJOURNAL OF CHEMOMETRICS, Issue 8 2008Davide Ballabio Abstract Different classification methods (Partial Least Squares Discriminant Analysis, Extended Canonical Variates Analysis and Linear Discriminant Analysis), in combination with variable selection approaches (Forward Selection and Genetic Algorithms), were compared, evaluating their capabilities in the geographical discrimination of wine samples. Sixty-two samples were analysed by means of dynamic headspace gas chromatography mass spectrometry (HS-GC-MS) and the entire chromatographic profile was considered to build the dataset. Since variable selection techniques pose a risk of overfitting when a large number of variables is used, a method for coupling data dimension reduction and variable selection was proposed. This approach compresses windows of the original data by retaining only significant components of local Principal Component Analysis models. The subsequent variable selection is then performed on these locally derived score variables. The results confirmed that the classification models achieved on the reduced data were better than those obtained on the entire chromatographic profile, with the exception of Extended Canonical Variates Analysis, which gave acceptable models in both cases. Copyright © 2008 John Wiley & Sons, Ltd. [source] Determination of glycyrrhetic acid in human plasma by HPLC-MS method and investigation of its pharmacokineticsJOURNAL OF CLINICAL PHARMACY & THERAPEUTICS, Issue 3 2008W.-J. Zhao PhD Summary Objective:, To develop a high performance liquid chromatography mass spectrometry (HPLC-MS) method for the determination of the glycyrrhetic acid (GA) in human plasma and for the investigation of its pharmacokinetics after the oral administration of 150 mg diammonium glycyrrhizinate test and reference capsule formulations. Methods:, The GA in plasma was extracted with ethyl acetate, separated on a C18 column with a mobile phase of methanol (5 mmol/L ammonium acetate),water (85 : 15, V/V) and analysed using a MS detector. Ursolic acid (UA) was used as internal standard. The target ions were m/z 469·5 for GA and m/z 455·6 for UA, the fragment voltages were 200 V and 100 V for GA and UA respectively. Results:, The calibration curve was linear over the range of 0·5,200 ng/mL (r = 0·9974). The limit of quantification for GA in plasma was 0·5 ng/mL, the recovery was 76·0,80·0%, and the inter- and intra-day relative standard deviations (RSD) were <12%. The pharmacokinetic parameters of GA after a single dose of 150 mg diammonium glycyrrhizinate test and reference were as follows: the half life (t1/2) 9·65 ± 3·54 h and 9·46 ± 2·85 h, the time to peak concentration (Tmax) 10·95 ± 1·32 h and 11·00 ± 1·30 h, the peak concentration (Cmax) 95·57 ± 43·06 ng/mL and 103·89 ± 49·24 ng/mL; the area under time-concentration curve (AUC0,48 and AUC0,,) 1281·84 ± 527·11 ng·h/mL and 1367·74 ± 563·27 ng·h/mL, 1314·32 ± 566·40 ng·h/mL and 1396·97 ± 630·06 ng·h/mL. The relative bioavailability of diammonium glycyrrhizinate capsule was 98·88 ± 12·98%. Conclusion:, The assay was sensitive, accurate and convenient, and can be used for the determination of GA in human plasma. Comparison of the bioavailability and pharmacokinetic profile of GA indicated that the test and reference capsules were bioequivalent. [source] Optimizing the Use of Garlic Oil as Antimicrobial Agent on Fresh-Cut Tomato through a Controlled Release SystemJOURNAL OF FOOD SCIENCE, Issue 7 2010J. Fernando Ayala-Zavala Abstract:, Encapsulation of garlic oil (GO) in ,-cyclodextrin (,-CD) was undertaken to generate a release system of antimicrobial volatiles and tested on microbial growth and sensory quality of fresh-cut tomato. GO volatile profile was characterized by gas chromatography mass spectrometry and to demonstrate the disadvantages of applying free GO to fresh-cut tomato, the effect of different free oil treatments (0, 50, 100, and 200 ,g/100 g) on microbial growth and sensorial quality was tested. The effect of GO capsules (0, 0.25, 0.5, and 1 g/100 g) on microbial growth and sensory quality of tomato was also investigated. Allyl disulfide was the most abundant GO compound identified. The release of volatiles from GO: ,-CD capsules (12: 88 [w/w] ratio) was evaluated at 100% relative humidity (RH). Close to 70% of GO volatiles were released from capsules when exposed to 100% RH during 5 wk. The most effective antimicrobial concentrations of free oil (100 and 200 ,g/100 g) applied to tomatoes did not present acceptable sensory quality for panelists. Tomato was affected by the highest concentration of GO capsules applied, showing the lowest microbial growth and the highest sensory quality. In this context, successful encapsulation in ,-CD could stimulate further interest in the use of GO for the control of microbial growth in fresh-cut tomato. Practical Application:, The present study demonstrated that relative humidity in-package of fresh-cut tomatoes can be used as a trigger to release antimicrobial garlic oil volatiles from ,-cyclodextrin capsules, reducing microbial growth and the sensory effect of the treatment caused by the free garlic oil. In this context, successful encapsulation in ,-cyclodextrin could stimulate further interest in the use of garlic oil for the control of microbial growth in fresh-cut tomatoes. [source] The Impact of Antioxidant Addition on Flavor of Cheddar and Mozzarella Whey and Cheddar Whey Protein ConcentrateJOURNAL OF FOOD SCIENCE, Issue 6 2010I.W. Liaw Abstract:, Lipid oxidation products are primary contributors to whey ingredient off-flavors. The objectives of this study were to evaluate the impact of antioxidant addition in prevention of flavor deterioration of fluid whey and spray-dried whey protein. Cheddar and Mozzarella cheeses were manufactured in triplicate. Fresh whey was collected, pasteurized, and defatted by centrifugal separation. Subsequently, 0.05% (w/w) ascorbic acid or 0.5% (w/w) whey protein hydrolysate (WPH) were added to the pasteurized whey. A control with no antioxidant addition was also evaluated. Wheys were stored at 3 °C and evaluated after 0, 2, 4, 6, and 8 d. In a subsequent experiment, selected treatments were then incorporated into liquid Cheddar whey and processed into whey protein concentrate (WPC). Whey and WPC flavors were documented by descriptive sensory analysis, and volatile components were evaluated by solid phase micro-extraction with gas chromatography mass spectrometry. Cardboard flavors increased in fluid wheys with storage. Liquid wheys with ascorbic acid or WPH had lower cardboard flavor across storage compared to control whey. Lipid oxidation products, hexanal, heptanal, octanal, and nonanal increased in liquid whey during storage, but liquid whey with added ascorbic acid or WPH had lower concentrations of these products compared to untreated controls. Mozzarella liquid whey had lower flavor intensities than Cheddar whey initially and after refrigerated storage. WPC with added ascorbic acid or WPH had lower cardboard flavor and lower concentrations of pentanal, heptanal, and nonanal compared to control WPC. These results suggest that addition of an antioxidant to liquid whey prior to further processing may be beneficial to flavor of spray-dried whey protein. Practical Application:, Lipid oxidation products are primary contributors to whey ingredient off-flavors. Flavor plays a critical and limiting role in widespread use of dried whey ingredients, and enhanced understanding of flavor and flavor formation as well as methods to control or minimize flavor formation during processing are industrially relevant. The results from this study suggest that addition of an antioxidant to liquid whey prior to further processing may be beneficial to minimize flavor of spray-dried whey protein. [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] Bank Security Dye Packs: Synthesis, Isolation, and Characterization of Chlorinated Products of Bleached 1-(methylamino)anthraquinoneJOURNAL OF FORENSIC SCIENCES, Issue 6 2006James M. Egan Ph.D. ABSTRACT: Banknote evidence is often submitted after a suspect has attempted to disguise or remove red dye stain that has been released because of an anti-theft device that activates after banknotes have been unlawfully removed from bank premises. Three chlorinated compounds have been synthesized as forensic chemical standards to indicate bank security dye bleaching as a suspect's intentional method for masking a robbery involving dye pack release on banknotes. A novel, facile synthetic method to provide three chlorinated derivatives of 1-(methylamino)anthraquinone (MAAQ) is presented. The synthetic route involved Ultra CloroxÔ bleach as the chlorine source, iron chloride as the catalyst, and MAAQ as the starting material and resulted in a three-component product mixture. Two mono-chlorinated isomers (2-chloro-1-(methylamino)anthraquinone and 4-chloro-1-(methylamino)anthraquinone) and one di-chlorinated compound (2,4-dichloro-1-(methylamino)anthraquinone) of the MAAQ parent molecule were detected by gas chromatography mass spectrometry (GC-MS), and subsequently isolated by liquid chromatography (LC) with postcolumn fraction collection. Although GC-MS is sensitive enough to detect all of the chlorinated products, it is not definitive enough to identify the structural isomers. Liquid-state nuclear magnetic resonance (NMR) spectroscopy was utilized to elucidate structurally the ortho- and para-mono-chlorinated isomers once enough material was properly isolated. A reaction mechanism involving iron is proposed to explain the presence of chlorinated MAAQ species on stolen banknotes after attempted bleaching. [source] Simultaneous determination of mono-, di- and tributyltin in environmental samples using isotope dilution gas chromatography mass spectrometryJOURNAL OF MASS SPECTROMETRY (INCORP BIOLOGICAL MASS SPECTROMETRY), Issue 5 2004Giuseppe Centineo Abstract The development of a rapid, precise and accurate speciation method for the simultaneous determination of mono-, di- and tributyltin in environmental samples is described. The method is based on using isotope dilution gas chromatography/mass spectrometry (GC/MS) with electron ionization, a widely used technique in routine testing laboratories. A mixed spike containing 119Sn-enriched monobutyltin (MBT), dibutyltin (DBT) and tributyltin (TBT) was used for the isotope dilution of the samples. Five molecular ions were monitored for each analyte, corresponding to the 116Sn, 117Sn, 118Sn, 119Sn and 120Sn isotopes. The detection at masses corresponding to 116Sn and 117Sn were used to correct for m + 1 and m + 2 contributions of 13C from the organic groups attached to the tin atom on the 118Sn, 119Sn and 120Sn masses with simple mathematical equations and the concentrations of the butyltin compounds were calculated based on the corrected 118Sn/119Sn and 120Sn/119Sn isotope ratios. The 119Sn-enriched multispecies spike was applied with satisfactory results to the simultaneous determination of MBT, DBT and TBT in three certified reference materials: two sediments, PACS-2 and BCR 646, and the mussel tissue CRM 477. The method was compared with a previously published GC/inductively coupled plasma MS isotope dilution procedure, developed in our laboratory, by injecting the same samples into both instruments. Comparable analytical results in terms of precision and accuracy are demonstrated for both atomic and molecular mass spectrometric detectors. Thus, reliable quantitative organotin speciation analysis can be achieved using the more widespread and inexpensive GC/MS instrument. Copyright © 2004 John Wiley & Sons, Ltd. [source] Use of L -[15N] glutamic acid and homoglutathione to determine both glutathione synthesis and concentration by gas chromatography-mass spectrometry (GCMS)JOURNAL OF MASS SPECTROMETRY (INCORP BIOLOGICAL MASS SPECTROMETRY), Issue 7 2001Bernard Humbert Abstract A method for simultaneous measurement of both glutathione enrichment and concentration in a biological sample using gas chromatography mass spectrometry is described. The method is based on the preparation of N,S -ethoxycarbonylmethyl ester derivatives of glutathione, and the use of homoglutathione (glutamyl,cysteinyl,alanine) as an internal standard. A procedure for determination of glutamate concentration and enrichment is also reported. Both methods have within-day and day-to-day inter-assay coefficients of variation less than 5%, and recoveries of known added amounts of glutathione and glutamate are close to 100%. Taken together, these methods allowed determination of glutathione concentration and fractional synthesis rate in red blood cells using L -[15N] glutamic acid infusion. This approach was applied in vivo to investigate the effects of a 72 h fast, compared with a control overnight fast, on erythrocyte glutathione in a single dog. The 72 h fast was associated with a 39% decline in erythrocyte glutathione level, (2.9 ± 0.4 versus 4.7 ± 0.5 mmol l,1, fasting versus control) with no change in glutathione fractional synthesis (67.4 versus 71.3% d,1, fasting versus control). Copyright © 2001 John Wiley & Sons, Ltd. [source] Determination of cosmetic ingredients causing extrusion-coated and adhesive joint multilayer packaging delaminationPACKAGING TECHNOLOGY AND SCIENCE, Issue 7 2009Álvaro Garrido-López Abstract In order to study the effect of several compounds on packaging stability, different cosmetic ingredients at two concentration levels were added to a NeoPCL® (Acofarma, Terrassa, Spain) water emulsion, and the preparations packed in sachets and stored at 40°C during 3 months. After that, the packaging was subjected to a T-peel test and headspace solid-phase microextraction gas chromatography mass spectrometry (HS-SPME-GC-MS) analysis. The HS-SPME-GC-MS analyses were performed using a 75,,m carboxen polydimethylsiloxane fibre to check for the presence of the studied analytes in the inner layers. The study revealed that the presence of a phenyl and a hydroxyl group in the compound structure lead to an important loss of adhesion between packaging layers joined by an adhesive. The interaction between the cosmetic ingredient and the adhesive was proposed as the main cause of the loss of adhesion. However, extrusion-coating packaging was more susceptible to delamination, particularly with the volatile compounds. Copyright © 2009 John Wiley & Sons, Ltd. [source] Regulation of insulin action by an extract of Artemisia dracunculus L. in primary human skeletal muscle culture: A proteomics approach,PHYTOTHERAPY RESEARCH, Issue 9 2010Indu Kheterpal Abstract An ethanolic extract of Artemisia dracunculus L. (PMI 5011) has been observed to decrease glucose and insulin levels in animal models and enhance cellular signaling in cultured cells. To determine the mechanism of action of PMI-5011, we have measured changes in protein expression in human primary skeletal muscle culture (HSMC) from subjects with Type 2 diabetes. After obtaining skeletal muscle biopsies, HSMCs were initiated, grown to confluence, and exposed to 10,µg/mL PMI 5011 overnight. Two-dimensional difference in-gel electrophoresis was used to separate proteins, and liquid chromatography mass spectrometry was used to identify differentially regulated proteins. Additionally, real-time polymerase chain reaction (PCR) was used to confirm candidate proteins identified. These data demonstrate that a well characterized botanical extract of Artemisia dracunculus L. significantly modulates proteins involved in regulating inflammatory pathways, particularly the NF,B complex system. Copyright © 2010 John Wiley & Sons, Ltd. [source] Effect of arbuscular mycorrhizal (AM) colonization on terpene emission and content of Artemisia annua L.PLANT BIOLOGY, Issue 1 2008F. Rapparini Abstract Plant roots interact with a wide variety of rhizospheric microorganisms, including bacteria and the symbiontic arbuscular mycorrhizal (AM) fungi. The mycorrhizal symbiosis represents a series of complex feedbacks between plant and fungus regulated by their physiology and nutrition. Despite the widespread distribution and ecological significance of AM symbiosis, little is known about the potential of AM fungi to affect plant VOC metabolism. The purpose of this study was to investigate whether colonization of plant roots by AM fungi and associated soil microorganisms affects VOC emission and content of Artemisia annua L. plants (Asteraceae). Two inoculum types were evaluated: one consisted of only an arbuscular mycorrhizal (AM) fungus species (Glomus spp.), and the other was a mixture of different Glomus species and associated soil bacteria. Inoculated plants were compared with non-inoculated plants and with plants supplemented with extra phosphorus (P) to obtain plants of the same size as mycorrhizal plants, thus excluding potentially-confounding mycorrhizal effects on shoot growth. VOC emissions of Artemisia annua plants were analyzed by leaf cuvette sampling followed by off-line measurements with pre-concentration and gas chromatography mass spectrometry (GC-MS). Measurements of CO2 and H2O exchanges were conducted simultaneously. Several volatile monoterpenes were identified and characterized from leaf emissions of Artemisia annua L. by GC-MS analysis. The main components identified belong to different monoterpene structures: ,-pinene, ,-pinene, camphor, 1,8-cineole, limonene, and artemisia ketone. A good correlation between monoterpene leaf concentration and leaf emission was found. Leaf extracts included also several sesquiterpenes. Total terpene content and emission was not affected by AM inoculation with or without bacteria, while emission of limonene and artemisia ketone was stimulated by this treatment. No differences were found among treatments for single monoterpene content, while accumulation of specific sesquiterpenes in leaves was altered in mycorrhizal plants compared to control plants. Growth conditions seemed to have mainly contributed to the outcome of the symbiosis and influenced the magnitude of the plant response. These results highlight the importance of considering the below-ground interaction between plant and soil for estimating VOC emission rates and their ecological role at multitrophic levels. [source] Proteomics of the rat gut: Analysis of the myenteric plexus-longitudinal muscle preparationPROTEINS: STRUCTURE, FUNCTION AND BIOINFORMATICS, Issue 10 2005Laure Marvin-Guy Abstract The enteric nervous system (ENS) , present all along the gastrointestinal tract , is the largest and most complicated division of the peripheral nervous system that can function independently of the brain. The peripheral nerve cells are organized in two separate but interconnected meshworks, called the myenteric and submucous plexus. The nervous control of intestinal motility is primarily governed by the myenteric plexus (MP), which lies in-between the longitudinal- (LM) and circular-muscle layers and regulates their functions. To determine whether the proteomic technology is adapted to the analysis of specific gut tissues, we dissected the MP-LM layers from the jejunum, ileum, and colon of Long Evans rats, homogenized them, and separated the proteins using two-dimensional gel electrophoresis. A subset of all the visualized protein spots, covering the entire range of molecular weights and isoelectric points, was then selected and further analyzed by matrix-assisted laser desorption/ionization-time of flight and liquid chromatography mass spectrometry. We identified around 80 proteins in each gut segment, and among those, five were segment-specific. Most of the proteins identified were derived from muscle cells, but we also detected some neuron-specific proteins. This study represents, to our knowledge, the first extensive protein catalog of a neuromuscular layer of the rat intestine and it may constitute the basis to understand pathophysiological mechanisms related to the ENS. [source] Comparison of gas chromatography and liquid chromatography mass spectrometric measurements for high accuracy analysis of cholesterol in human serum by isotope dilution mass spectrometryRAPID COMMUNICATIONS IN MASS SPECTROMETRY, Issue 9 2002Céline S. J. Wolff Briche Cholesterol measurements are of vital clinical importance and reliable reference materials are essential for method validation. Gas chromatography with mass spectrometry (GC/MS) is usually used for the high accuracy analysis of cholesterol by isotope dilution. A certified reference material for cholesterol content in human serum was analysed by isotope dilution utilising GC/MS and liquid chromatography mass spectrometry (LC/MS). The use of LC/MS avoided the need for a derivatisation step. Both LC/MS and GC/MS produced results on the measurement of cholesterol that agreed within 0.5% of the certified value. Moreover, the precision obtained for ratio measurement using both techniques are comparable and lead to relative expanded standard uncertainties (with a coverage factor of 2) varying between 0.2 and 0.5%. Copyright © 2002 John Wiley & Sons, Ltd. [source] Methotrexate catabolism to 7-hydroxymethotrexate in rheumatoid arthritis alters drug efficacy and retention and is reduced by folic acid supplementationARTHRITIS & RHEUMATISM, Issue 8 2009Joseph E. Baggott Objective To assess the catabolism of methotrexate (MTX) to 7-hydroxy-MTX (7-OH-MTX) in patients with rheumatoid arthritis as well as the effect of folic acid and folinic acid on this catabolism. Methods Urinary excretion of MTX and its catabolite, 7-OH-MTX, was measured in 2 24-hour urine specimens collected after MTX therapy. Urine samples were collected from patients after the sixth and seventh weekly doses of MTX. MTX and 7-OH-MTX concentrations were determined by high-performance liquid chromatography mass spectrometry. Swelling and pain/tenderness indices were used to measure symptoms before and at 6 and 7 weeks of therapy. Patients received either folic acid or folinic acid supplements (1 mg/day) from week 6 to week 7. Results Folic acid inhibited aldehyde oxidase (AO), the enzyme that produces 7-OH-MTX, but folinic acid did not. Excretion of 7-OH-MTX (determined as a percentage of the dose of MTX or as mg 7-OH-MTX/gm creatinine) was not normally distributed (n = 39). Patients with marked improvement in swelling and pain/tenderness indices had a lower mean 7-OH-MTX excretion level (P < 0.05). Patients who received folic acid supplements had decreased 7-OH-MTX excretion (P = 0.03). Relatively high 7-OH-MTX excretion was correlated with relatively high MTX excretion and with relatively low MTX retention in vivo (P < 0.05) (n = 35). Conclusion Our findings of a non-normal distribution of 7-OH-MTX excretion suggest that there are at least 2 phenotypes for this catabolism. Decreased 7-OH-MTX formation suggests folic acid inhibition of AO and a better clinical response, while increased 7-OH-MTX formation may interfere with MTX polyglutamylation and binding to enzymes and, therefore, may increase MTX excretion and decrease MTX retention and efficacy in vivo. [source] Quantification of acetylcholine, an essential neurotransmitter, in brain microdialysis samples by liquid chromatography mass spectrometryBIOMEDICAL CHROMATOGRAPHY, Issue 1 2010Ramakrishna Nirogi Abstract Chemical neurotransmission has been the subject of intensive investigations in recent years. Acetylcholine is an essential neurotransmitter in the central nervous system as it has an effect on alertness, memory and learning. Enzymatic hydrolysis of acetylcholine in the synaptic cleft is fast and quickly metabolizes to choline and acetate by acetylcholinesterase. Hence the concentration in the extracellular fluid of the brain is low (0.1,6,nm). Techniques such as microdialysis are routinely employed to measure acetylcholine levels in living brain systems and the microdialysis sample volumes are usually less than 50,µL. In order to develop medicine for the diseases associated with cognitive dysfunction like mild cognitive impairment, Alzheimer's disease, schizophrenia and Parkinson's disease, or to study the mechanism of the illness, it is important to measure the concentration of acetylcholine in the extracellular fluid of the brain. Recently considerable attention has been focused on the development of chromatographic,mass spectrometric techniques to provide more sensitive and accurate quantification of acetylcholine collected from in-vivo brain microdialysis experiments. This review will provide a brief overview of acetylcholine biosynthesis, microdialysis technique and liquid chromatography mass spectrometry, which is being used to quantitate extracellular levels of acetylcholine. Copyright © 2009 John Wiley & Sons, Ltd. [source] Fungal biodegradation of hard coal by a newly reported isolate, Neosartorya fischeriBIOTECHNOLOGY JOURNAL, Issue 11 2008Eric E. Igbinigie Abstract Cynodon dactylon (Bermuda grass) has been observed to grow sporadically on the surface of coal dumps in the Witbank coal mining area of South Africa. Root zone investigation indicated that a number of fungal species may be actively involved in the biodegradation of hard coal, thus enabling the survival of the plant, through mutualistic interaction, in this extreme environment. In an extensive screening program of over two thousand samples, the Deuteromycete, Neosartorya fischeri, was isolated and identified. The biodegradation of coal by N. fischeri was tested in flask studies and in a perfusion fixed-bed bioreactor used to simulate the coal dump environment. The performance of N. fischeri was compared to Phanaerochaete chrysosporium and Trametes (Polyporus) versicolor, previously described in coal biodegradation studies. Fourier transform infrared spectrometry and pyrolysis gas chromatography mass spectrometry of the biodegradation product indicated oxidation of the coal surface and nitration of the condensed aromatic structures of the coal macromolecule as possible reaction mechanisms in N. fischeri coal biodegradation. This is a first report of N. fischeri -mediated coal biodegradation and, in addition to possible applications in coal biotechnology, the findings may enable development of sustainable technologies in coal mine rehabilitation. [source] Oxidation kinetics of pentachlorophenol by manganese dioxideENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 11 2006Ling Zhao Abstract This study examined the abiotic transformation kinetics of pentachlorophenol (PCP) by manganese dioxide (MnO2) at different solution chemistry and initial concentrations of PCP and MnO2. The measured PCP transformation rates were found to be on the order of 1.07 with respect to [PCP] and 0.91 and 0.87 with respect to [MnO2] and [H+], respectively. Dissolved Mn2+ and Ca2+ as background electrolytes considerably decreased the reaction rate because of their adsorption and hence blocking of active sites on MnO2 surfaces. The dechlorination number, 0.59 chloride ions per transformed PCP after a 1-h reaction, suggests that a fraction of the transformed PCP was not dechlorinated and may be coupled directly to dimeric products. Gas chromatography/ mass spectrometry and liquid chromatography/mass spectrometry/mass spectrometry techniques were used to identify two isomeric nonachlorohydroxybiphenylethers as major products and 2,3,5,6-tetrachloro-1,4-hydroquinone and tetrachlorocatechol as minor products. Product identification suggested that the reaction may include two parallel reactions to form either dimers or 2,3,5,6-tetrachloro-1,4-hydroquinone and tetrachlorocatechol via simultaneous dehydrochlorination and hydroxylation. [source] Effect of Gamma-irradiation on Color, Pungency, and Volatiles of Korean Red Pepper PowderJOURNAL OF FOOD SCIENCE, Issue 8 2004J.H. Lee ABSTRACT: Effect of gamma-irradiation on color, pungency, and volatiles of Korean red pepper powder (Capsicum annuum L.) was investigated. Red pepper powder, vacuum-packaged in a polyethylene/polypropylene bag, was gamma-irradiated up to 7 kGy. An irradiation dose of 7 kGy reduced the population of mesophilic bacteria and fungi effectively without affecting major quality factors. Pungency of irradiated red pepper powder was not changed based on the amount of capsanoids by high-performance liquid chromatography (HPLC) and the Scoville sensory score. The red color of irradiated pepper powder was not significantly different from that of the control, judged from the capsanthin content by HPLC and color assessment using spectrophotpmetric (American Spice Trade Assn. units) and colorimetric measurements (Hunter a values). Further, the sensory evaluation showed no significant difference in pungent odor and off-odor between nonirradiated control and irradiated red pepper powder. However, when headspace volatiles of gamma-irradiated red pepper powder were evaluated by gas chromatography/ mass spectrometry with solid-phase microextraction and electronic nose with metal oxide sensors, the profiles of odor were classified into irradiated dose levels of 0, 3, 5, and 7 kGy by principal component analysis and multivariate analysis of variance. Such a difference of odor might result from the disappearance of some volatiles, such as hexanoic acid and tetramethyl-pyrazine, and the appearance of 1,3-di-tert-butylbenzene during irradiation. Moreover, it appears that the irradiation of packaging material induced a formation of 1,3-di-tertbutylbenzene, which migrated into the red pepper powder. [source] Derivatisation for liquid chromatography/electrospray mass spectrometry: synthesis of pyridinium compounds and their amine and carboxylic acid derivativesRAPID COMMUNICATIONS IN MASS SPECTROMETRY, Issue 6 2003Samantha J. Barry A simple method has been developed for the pre-column derivatisation of low molecular weight primary and secondary amines and carboxylic acids using quaternary nitrogen compounds to enhance their detection by liquid chromatography/electrospray ionisation mass spectrometry (LC/ESI-MS). The synthesis of seven novel quaternary nitrogen reagents is described. The derivatives are designed to be relatively small molecules to avoid some of the steric hindrance problems that may be associated with larger derivatisation reagents. The compounds have amine and carboxylic acid functional groups with which to derivatise carboxylic acids and amines, respectively. Two of the compounds contain a bromine atom in order to assess the advantages of a bromine isotope pattern in the mass spectra. This acts as a simple marker for derivatisation and enables data processing by cluster analysis. Activation of the carboxylic acid group was achieved by the use of either 1-chloro-4-methylpyridinium iodide (CMPI) or the more reactive 1-fluoro-4-methylpyridinium p -toluenesulphonate (FMP).1 Using both of these active reagents, the degree of nucleophilic substitution was investigated for the derivatisation of a variety of small molecules. Whilst giving some increase in the ESI-MS response for the derivatised compounds, the FMP itself acted as a derivatising reagent in a competing reaction. In the light of this finding, FMP was reacted with the test compounds separately and gave positive results as a derivatising reagent. Detection of the ,pre-charged' derivatives of amines and carboxylic acids by LC/ESI-MS was investigated with respect to their ESI response and chromatography. Copyright © 2003 John Wiley & Sons, Ltd. [source] Derivatization for liquid chromatography/electrospray mass spectrometry: synthesis of tris(trimethoxyphenyl)phosphonium compounds and their derivatives of amine and carboxylic acidsRAPID COMMUNICATIONS IN MASS SPECTROMETRY, Issue 5 2002William J Leavens A simple method for the derivatization of primary amines and carboxylic acids with tris(trimethoxyphenyl)phosphonium (TMPP) reagents to enhance their detection by electrospray mass spectrometry (ESI-MS) has been developed. The synthesis of novel TMPP reagents and their stable isotopically labelled analogues is described. Through the use of stable isotopically labelled TMPP ,tags', incorporation of a doublet (1:1, 1H/2H or 12C/13C) into the target molecule can be achieved, enabling the use of isotopic target analysis to detect compounds of unknown molecular weight but with a characteristic isotope pattern and accurate mass difference. Copyright © 2002 John Wiley & Sons, Ltd. [source] Improved detection of reactive metabolites with a bromine-containing glutathione analog using mass defect and isotope pattern matchingRAPID COMMUNICATIONS IN MASS SPECTROMETRY, Issue 9 2010André LeBlanc Drug bioactivation leading to the formation of reactive species capable of covalent binding to proteins represents an important cause of drug-induced toxicity. Reactive metabolite detection using invitro microsomal incubations is a crucial step in assessing potential toxicity of pharmaceutical compounds. The most common method for screening the formation of these unstable, electrophilic species is by trapping them with glutathione (GSH) followed by liquid chromatography/mass spectrometry (LC/MS) analysis. The present work describes the use of a brominated analog of glutathione, N -(2-bromocarbobenzyloxy)-GSH (GSH-Br), for the invitro screening of reactive metabolites by LC/MS. This novel trapping agent was tested with four drug compounds known to form reactive metabolites, acetaminophen, fipexide, trimethoprim and clozapine. Invitro rat microsomal incubations were performed with GSH and GSH-Br for each drug with subsequent analysis by liquid chromatography/high-resolution mass spectrometry on an electrospray time-of-flight (ESI-TOF) instrument. A generic LC/MS method was used for data acquisition, followed by drug-specific processing of accurate mass data based on mass defect filtering and isotope pattern matching. GSH and GSH-Br incubations were compared to control samples using differential analysis (Mass Profiler) software to identify adducts formed via the formation of reactive metabolites. In all four cases, GSH-Br yielded improved results, with a decreased false positive rate, increased sensitivity and new adducts being identified in contrast to GSH alone. The combination of using this novel trapping agent with powerful processing routines for filtering accurate mass data and differential analysis represents a very reliable method for the identification of reactive metabolites formed in microsomal incubations. Copyright © 2010 John Wiley & Sons, Ltd. [source] Characterization of atenolol transformation products on light-activated TiO2 surface by high-performance liquid chromatography/high-resolution mass spectrometryRAPID COMMUNICATIONS IN MASS SPECTROMETRY, Issue 1 2009Claudio Medana No abstract is available for this article. [source] High-throughput analysis in drug discovery: application of liquid chromatography/ion-trap mass spectrometry for simultaneous cassette analysis of ,-1a antagonists and their metabolites in mouse plasmaRAPID COMMUNICATIONS IN MASS SPECTROMETRY, Issue 8 2001Zongwei Cai The application of liquid chromatography/ion-trap mass spectrometry for simultaneous quantification of multiple drugs and detection of their metabolites for in vitro experiments was reported recently. In the current study, the use of these techniques was extended to in vivo pharmacokinetic (PK) studies of ,-1a antagonists. In combination with limited time-point PK, greatly increased throughput was demonstrated for the in vivo screening and investigation of in vivo,in vitro correlation. In addition to quantitative analyses, the technique allowed simultaneous detection of major in vivo metabolites without having to reanalyze the plasma samples. The drugs were individually dosed in mice intravenously via tail vein injection and the blood samples were collected 5,min and 2,h after dosing. After the plasma samples for the different drugs had been prepared separately, they were pooled for cassette analysis. The concentrations of five test compounds in the plasma samples at 2,h ranged from 36,1062,ng/mL, whereas their 5-min plasma levels were similar. From the same cassette analysis, major metabolites in the samples were also detected simultaneously through the interpretation of full-scan mass spectra. The metabolite identification confirmed the results from a previous report that the major sites of metabolism are hydroxylation of the phenyl ring not bearing the alkylsulfonamide substitutent, piperidine N-dealkylation, and N-demethylation of the alkylsulfonamide group. Copyright © 2001 John Wiley & Sons, Ltd. [source] Identification of lysophosphatidylcholine (LPC) and platelet activating factor (PAF) from PC12 cells and mouse cortex using liquid chromatography/multi-stage mass spectrometry (LC/MS3)RAPID COMMUNICATIONS IN MASS SPECTROMETRY, Issue 22 2008Jeffrey C. Smith Lipids play essential roles in cellular structural support, energy storage and signal transduction. Recently, mass spectrometry (MS) has been used to produce three-dimensional maps that elucidate the lipid composition of complex cellular lysates. The identification of individual lipids within these maps is slow and requires the synthesis and spiking of each candidate lipid. We present a novel MS-based technique that rapidly elucidates the atomic connectivity of the fatty acid/alcohol substituent on the sn -1 position of several different families of glycerophosphocholine-containing lipids within the confines of a chromatographic separation. Sodiated lipid species were fragmented to produce radical cations which lost successive methylene groups upon further collisional activation to reveal the identity of the parent molecule. This approach was demonstrated to be effective on isobaric members of the lysophosphatidylcholine (LPC) and platelet activating factor (PAF) families of glycerophospholipids. We demonstrate the application of this technique to unambiguously identify these species within complex cellular lysates and tissue extracts. Copyright © 2008 John Wiley & Sons, Ltd. [source] Determination of radix ginseng volatile oils at different ages by comprehensive two-dimensional gas chromatography/time-of-flight mass spectrometryJOURNAL OF SEPARATION SCIENCE, JSS, Issue 19 2008Yaqiong Qiu Abstract Comprehensive 2-D GC (GC×GC) coupled with TOF MS or flame ionization detector (FID) was employed to characterize and quantify the chemical composition of volatile oil in the radixes of Panax ginseng C. A. Mey. (ginseng) at different ages. Thirty-six terpenoids were tentatively identified based on the MS library search and retention index in a ginseng sample at the age of 3 years. An obvious group-type separation was obtained in the GC×GC-TOF MS chromatogram. The data collected by GC×GC-FID were processed using a principal component analysis (PCA) method to classify the samples at different ages. The compounds responsible for the significant differentiation among samples were defined. It was found that the relative abundances of ,-cadinol, ,-bisabolol, thujopsene, and n -hexadecanoic acid significantly rise with the increase in age. [source] | ||||||||||||||||||||||||||||