Gas-liquid-chromatographic determination of light-dependent acetylcholine concentrations in moss callus.
Ontology highlight
ABSTRACT:
SUBMITTER: Hartmann E
PROVIDER: S-EPMC1166111 | biostudies-other | 1974 Feb
REPOSITORIES: biostudies-other
Similar Datasets
Project description:A sensitive electron-capture gas-liquid-chromatographic method for the determination of sub-nanogram quantities of prostaglandin F(2alpha) was developed. The method is based on the sub-microgram scale conversion of the prostaglandin into the electron-capturing pentafluorobenzyl ester, and analysis of the latter as the tris-trimethylsilyl ether. The lower limit of detection was 12.5pg of the ester injected ;on-column' as the silylated product. The method was successfully applied to the determination of prostaglandin F(2alpha) in monkey plasma. The specificity of the analytical procedure was increased by incorporating a thin-layer chromatographic fractionation before gas-liquid chromatography. The utility of the analytical methodology developed was demonstrated by its application to the determination of plasma concentrations of intact prostaglandin F(2alpha) in a Rhesus monkey, after subcutaneous administration of a single dose of prostaglandin F(2alpha). The electron-capture gas-liquid-chromatographic assay is compared with the radioimmunoassay and the gas-liquid-chromatographic-mass-spectrometry assay for the determination of prostaglandin F(2alpha).
| S-EPMC1168065 | biostudies-other
Project description:A rapid, selective and sensitive ultra-performance liquid chromatography method has been developed for the detection and quantification of tocopherols and retinol in human plasma. Alpha-tocopherol, gamma-tocopherol and retinol are assayed using fluorescence detection. Excitation/emission wavelengths are 295/330 nm and 325/470 nm for the analysis of both tocopherols and retinol, respectively. Retinol acetate is employed as the internal standard. The reversed-phase method incorporates gradient elution with a mobile phase consisting of methanol and acetonitrile. Separation of vitamin compounds is achieved using a bridged ethyl hybrid C18 column. The retention times for retinol, retinol acetate, gamma-tocopherol and alpha-tocopherol are 1.6, 1.8, 3.9 and 4.3 min, respectively. The limits of quantification for retinol, gamma-tocopherol and alpha-tocopherol were 0.02, 0.02 and 0.1 µg/mL, respectively. The assay method is suitable for the analysis of tocopherols and retinol in human plasma. The method may be applied following the ingestion of foods fortified with these fat-soluble vitamins.
| S-EPMC4415074 | biostudies-other
Project description:Monitoring of biogenic amines in food is important for quality control, in terms of freshness evaluation and even more for food safety. A novel and cost-effective method was developed and validated for the determination of the main biogenic amines: histamine, putrescine, cadaverine, spermidine and spermine in fish tissues. The method includes extraction of amines with perchloric acid, pre-column derivatization with Pyrene Sulfonyl Chloride (PSCl), extraction of derivatives with toluene, back-dissolution in ACN after evaporation and determination by reversed phase high performance liquid chromatography with UV and intramolecular excimer fluorescence detection. The structure of the pyrene-derivatives was confirmed by liquid chromatography-mass spectrometry with electrospray ionization. The standard addition technique was applied for the quantitation due to significant matrix effect, while the use of 1,7-diaminoheptane as internal standard offered an additional confirmation tool for the identification of the analytes. Method repeatability expressed as %RSD ranged between 7.4-14% for the different amines and recovery ranged from 67% for histamine up to 114% for spermine. The limits of detection ranged between 0.1-1.4 mg kg-1 and the limits of quantification between 0.3-4.2 mg kg-1. The method was applied to canned fish samples and the concentrations of the individual biogenic amines were below the detection limit up to 40.1 mg kg-1, while their sum was within the range 4.1-49.6 mg kg-1.
| S-EPMC7278825 | biostudies-literature
Project description:Concentrations of circulating 24S-hydroxycholesterol (24SOHChol) are of interest as a practical measure of cholesterol efflux from the human brain. The current method of choice for 24SOHChol quantification is with gas chromatography-mass spectrometry (GC-MS). Liquid chromatography-mass spectrometry (LC-MS) methods to detect 24SOHChol have been described, but they lack rigorous high-performance liquid chromatography (HPLC) separation of a closely eluting isomeric oxysterol, 25-hydroxycholesterol. This is important because 25-hydroxycholesterol can be present in significant amounts and tandem mass spectrometry (MS/MS) cannot completely differentiate 24SOHChol. We describe an LC-MS method with rapid chromatographic separation of the oxysterols to permit accurate determination of plasma 24SOHChol. The availability of an LC-MS method offers advantages such as simplified sample work-up and analysis.
| S-EPMC2562163 | biostudies-literature
Project description:Purpose. Developing a validated HPLC-DAD method for simultaneous determination of posaconazole (PSZ) and vincristine (VCR) in rat plasma. Methods. PSZ, VCR, and itraconazole (ITZ) were extracted from 200 μL plasma using diethyl ether in the presence of 0.1 M sodium hydroxide solution. The organic layer was evaporated in vacuo and dried residue was reconstituted and injected through HC-C18 (4.6 × 250 mm, 5 μm) column. In the mobile phase, acetonitrile and 0.015 M potassium dihydrogen orthophosphate (30 : 70 to 80 : 20, linear gradient over 7 minutes) pumped at 1.5 mL/min. VCR and PSZ were measured at 220 and 262 nm, respectively. Two Sprague Dawley rats were orally dosed PSZ followed by iv dosing of VCR and serial blood sampling was performed. Results. VCR, PSZ, and ITZ were successfully separated within 11 min. Calibration curves were linear over the range of 50-5000 ng/mL for both drugs. The CV% and % error of the mean were ≤18% and limit of quantitation was 50 ng/mL for both drugs. Rat plasma concentrations of PSZ and VCR were simultaneously measured up to 72 h and their calculated pharmacokinetics parameters were comparable to the literature. Conclusion. The assay was validated as per ICH guidelines and is appropriate for pharmacokinetics drug-drug interaction studies.
| S-EPMC4807048 | biostudies-literature
Project description:Intact methionine residues in proteins were rapidly and precisely determined by measuring methyl thiocyanate released during the reaction with CNBr and separated by g.l.c. Conditions for the reaction and for chromatography on columns of Porapak P-S are described. The recovery of methyl thiocyanate from several methionine derivatives and analogues were examined. Carbamoylmethionine was adopted as a stable primary standard and ethyl thiocyanate as internal standard. The measured methionine content of several isolated proteins was close to the theoretical value indicated by previous work and the results for these and a range of food proteins agreed well with results obtained by ion-exchange chromatography after performic acid oxidation. Since CNBr does not react with methionine sulphoxide and a preliminary hydrolysis is not required, the method discriminates between methionine and any methionine sulphoxide that may be present. It could be useful in studies on the nutritional availability of methionine in processed foods.
| S-EPMC1172884 | biostudies-other
Project description:Polyvinyl acetate (PVAc) is used in various adhesive, paint, and transparent tape applications. It is also used as a food additive in food manufacturing to make chewing gum and fruit and vegetable glazes; however, guidelines on the amount of food additives that is used have not yet been established. In this study, a method was developed for analysis of polyvinyl acetate (PVAc) using high-performance liquid chromatography with an evaporative light scattering detector (HPLC-ELSD) and pyrolyzer-gas chromatography-mass spectrometry (Py-GC-MS). The analytical methods were applied to commercially available chewing gum. In the HPLC-ELSD analysis, the linearity was acceptable (R2 > 0.999), and the limits of detection and quantification were 22.2 and 67.3 µg/mL, respectively. The accuracies of PVAc were 87-115% at spike levels of 200-1000 µg/mL for the intra- and inter-day tests. The contents of PVAc in the chewing gum samples were n.d. (not detected)-13.8 g/kg. The presence of PVAc in chewing gum was verified with Py-GC-MS analysis, finding the typical pyrolysates of PVAc, such as acetic acid, benzene, toluene, styrene, indane, naphthalene, and acenaphthene. The developed analytical methods can be applied for successful identification of PVAc in chewing gum.
| S-EPMC7602758 | biostudies-literature
Project description:The Phenomenex EZ:faast amino acid analysis kit is available for gas (GC) or liquid (LC) chromatographic analysis of amino acids (AA) using mass spectrometry (MS) and other GC detectors. We used it for rapid GC determination of plasma tryptophan, its brain uptake competitors (Val, Leu, Ile, Phe and Tyr) and many other amino acids. Based on solid-phase extraction, this fast method enables one person to process two plasma samples in 8-10 min and six samples in approximately 15 min up to GC injection and a 7-min GC run per plasma sample. Using a Perkin-Elmer Clarus 500 GC, a Total Chrome software, a flame-ionisation detector (FID) and norvaline as internal standard, we used this method to analyse approximately 1,000 plasma samples from normal subjects undergoing acute tryptophan depletion and loading tests. The limit of detection for most amino acids is 1 nmol/ml (1 microM) and in many cases less. With manual injection, coefficients of variation for the above six amino acids were 1.5-6.2% (intra-assay) and 3.8-9.7% (inter-assay). This simple, rapid and elegant method will be valuable to the amino acid analyst and researcher, as it can save much manpower time and meet urgent emergency requests and the demands of a high-throughput laboratory.
| S-EPMC2797848 | biostudies-other
Project description:Several polychlorinated biphenyls (PCBs) and their hydroxylated metabolites display axial chirality. Here we describe an enantioselective, gas chromatographic separation of methylated derivatives of hydroxylated (OH-)PCB atropisomers (MeO-PCB) using a chemically bonded beta-cyclodextrin column (Chirasil-Dex). The atropisomers of several MeO-PCBs could be separated on this column with resolutions ranging from 0.42 to 0.87 under isothermal or temperature-programmed conditions. In addition, the enantiomeric fraction of OH-PCB 136 metabolites was determined in male and female rats treated with racemic PCB 136. The methylated derivatives of two OH-PCB 136 metabolites showed an enantiomeric enrichment in liver tissue, whereas PCB 136 itself was near racemic.
| S-EPMC2579784 | biostudies-literature
Project description:Acidosis is an important cause of mortality in severe falciparum malaria. Lactic acid is a major contributor to metabolic acidosis, but accounts for only one-quarter of the strong anion gap. Other unidentified organic acids have an independent strong prognostic significance for a fatal outcome. In this study, a simultaneous bio-analytical method for qualitative and quantitative assessment in plasma and urine of eight small organic acids potentially contributing to acidosis in severe malaria was developed and validated. High-throughput strong anion exchange solid-phase extraction in a 96-well plate format was used for sample preparation. Hydrophilic interaction liquid chromatography (HILIC) coupled to negative mass spectroscopy was utilized for separation and detection. Eight possible small organic acids; l-lactic acid (LA), ?-hydroxybutyric acid (aHBA), ?-hydroxybutyric acid (bHBA), p-hydroxyphenyllactic acid (pHPLA), malonic acid (MA), methylmalonic acid (MMA), ethylmalonic acid (EMA) and ?-ketoglutaric acid (aKGA) were analyzed simultaneously using a ZIC-HILIC column with an isocratic elution containing acetonitrile and ammonium acetate buffer. This method was validated according to U.S. Food and Drug Administration guidelines with additional validation procedures for endogenous substances. Accuracy for all eight acids ranged from 93.1% to 104.0%, and the within-day and between-day precisions (i.e. relative standard deviations) were lower than 5.5% at all tested concentrations. The calibration ranges were: 2.5-2500?g/mL for LA, 0.125-125?g/mL for aHBA, 7.5-375?g/mL for bHBA, 0.1-100?g/mL for pHPLA, 1-1000?g/mL for MA, 0.25-250?g/mL for MMA, 0.25-100?g/mL for EMA, and 30-1500?g/mL for aKGA. Clinical applicability was demonstrated by analyzing plasma and urine samples from five patients with severe falciparum malaria; five acids had increased concentrations in plasma (range LA=177-1169?g/mL, aHBA=4.70-38.4?g/mL, bHBA=7.70-38.0?g/mL, pHPLA=0.900-4.30?g/mL and aKGA=30.2-32.0) and seven in urine samples (range LA=11.2-513?g/mL, aHBA=1.50-69.5?g/mL, bHBA=8.10-111?g/mL, pHPLA=4.30-27.7?g/mL, MMA=0.300-13.3?g/mL, EMA=0.300-48.1?g/mL and aKGA=30.4-107?g/mL). In conclusion, a novel bioanalytical method was developed and validated which allows for simultaneous quantification of eight small organic acids in plasma and urine. This new method may be a useful tool for the assessment of acidosis in patients with severe malaria, and other conditions complicated by acidosis.
| S-EPMC3827507 | biostudies-literature