2-Dimethylarsinothioyl acetic acid identified in a biological sample: the first occurrence of a mammalian arsinothioyl metabolite.
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Acetates↗
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Simple method to measure power density entering a plane biological sample at millimeter wavelengths.
A simple method for measuring microwave power density is described. It is applicable to situations where exposure of samples in the near field of a horn is necessary. A transmitted power method is used to calibrate the power density entering the surface of the sample. Once the calibration is available, the power density is known in terms of the incident and reflected powers within the waveguide. The calibration has been carried out for liquid samples in a quartz cell. Formulas for calculating specific absorption rate (SAR) are derived in terms of the power density and the complex dielectric constant of the sample. An error analysis is also given.
Calibration↗
HPLC determination of orthophosphate coexisting with large amounts of organophosphates in biological samples.
A simple and accurate HPLC method for the determination of orthophosphate in the presence of large amounts of organophosphates is described. The method is based on the formation and separation of the molybdenum orthophosphate complex. In order to prevent the hydrolysis of organophosphates, the sample was deproteinized with silicotungstate in acetate buffer (pH 4.0) under ice-cooling and then treated with ammonium molybdate in maleate buffer (pH 7.0). The sample was injected onto Styragel 60 A column (5 mm ID x 100 mm) with 38% (v/v) acetonitrile containing 0.3 M sulfuric acid as eluent. Detection was at 310 nm. The method was applied to the determination of orthophosphate in liver, kidney, spleen and mouse blood.
Animals↗
Comparative performance of ion exchange and ion-paired reversed phase high performance liquid chromatography for the determination of nucleotides in biological samples.
We have compared anion exchange chromatography on APS-Hypersil (4.6 x 100 mm) eluted with a phosphate gradient with reversed phase chromatography on ODS-Hypersil (4.6 x 100 mm) in the presence of either tetrabutylammonium (TBA) or triethylammonium (TEA) ions with a methanol gradient. The systems have been compared both for ease of operation and for their resolving power with standard mixtures and acid extracts of both normal red cells (RBC) and ischaemic tissues. The two chromatographic modes exhibited similar separating efficiencies for standard mixtures of nucleotides but retention times were most stable using reversed phase liquid chromatography (RPLC) with TEA. Anion exchange columns slowly lost ion exchange capacity but selectivity was unchanged. RPLC in the presence of TBA gave reproducibile capacity factors only when operated isocratically due to irreversible changes to the silica surface. For RBCs the RPLC with TEA and anion exchange systems resolved 17 and 15 peaks, respectively, and for the ischaemic samples 22 and 14 peaks, respectively. However, nucleosides and bases were also resolved by the ODS column causing chromatographic crowding and uncertain peak identification.
Animals↗
Chromatographic determination method for 1-nitropyrene and its metabolites in biological samples with fluorescence detection after on-line reduction.
A high performance liquid chromatographic (HPLC) method with fluorescence detection after on-line reduction for the determination of 1-nitropyrene (NP), 1-nitrosopyrene (NSP), 1-aminopyrene (AP) and N-acetylaminopyrene (AAP) has been developed. The reduction efficiency of NP and NSP on a zinc column was found to be higher than that of an electrochemical reducer. Using a HPLC system equipped with a zinc column (4.0 mm i.d. x 10 mm) and an imidazole/HClO4 (pH 6.8): acetonitrile mobile phase, detection limits (S/N = 3) of 20-30 fmol for NP, NSP and AP and 350 fmol for AAP were obtained. NP, NSP and AP were determined in the incubation mixture of NP and Salmonella typhimurium, YG1021, by this method. Time course studies showed that a large ratio of NP was metabolized in the pre-incubation step of the Ames test.
Acetonitriles↗
A fully automated HPLC method for the determination of catecholamines in biological samples utilizing ethylenediamine condensation and peroxyoxalate chemiluminescence detection.
A fully automated in-line extraction reversed-phase high-performance liquid chromatography (HPLC) method with chemiluminescence detection was developed for the analysis of human and rat plasma catecholamines (CAs), norepinephrine (NE), epinephrine (E) and dopamine (DA). N-Methyldopamine (N-MeDA) was used as an internal standard. The method involves collection of plasma samples, which are first diluted with a sample dilution buffer containing N-MeDA, and in-line extraction of CAs using a carboxylic acid small resin precolumn (SERUMOUT-CEX). This pre-extraction process was coupled with an HPLC system including reversed-phase mode separation on an analytical column (TSK gel ODS-80Ts), fluorogenic derivatization with ethylenediamine (ED) and finally postcolumn peroxyoxalate chemiluminescence reaction detection using bis [4-nitro-2-(3,6,9-trioxadecyloxycarbonyl)phenyl]oxalate (TDPO) and hydrogen peroxide. The optimized mobile phase compositions, flow rates, operation timing for the adsorption and desorption of CAs in the precolumn, the separation in the analytical column and the optimum fluorogenic and chemiluminogenic reaction conditions were investigated. The detection limit for all the CAs was about 1 fmol (signal-to-noise ratio is 2). Excellent linearity of the calibration curves for CAs was observed in the range from 5 to 500 fmol for each CA using the internal standard. The relative standard deviations of the method for determining NE (183 fmol), E (23.6 fmol) and DA (6.1 fmol) in 50 microL of human plasma (n = 3) were 2.8, 2.7 and 3.1%, respectively, for the within-day assay and 5.0, 3.8 and 4.0%, respectively, for the between-day assay. The method was applicable to the determination of CAs in 25-50 microL of human or rat plasma.
Animals↗
Determination of organochlorine compounds in human biological samples by GC-MS/MS.
A study was undertaken to determine the extent of organochlorine pesticide (OP) and polychlorinated biphenyl (PCB) contamination in infant formula milk and in the human milk, fat and serum of women from an agricultural area in Southern Spain. A procedure is proposed that simultaneously detects trace levels of lindane, endosulfan-ether, vinclozolin, aldrin, endosulfan-lactone, endosulfan-alpha, 4,4'DDE, 2,4'DDT, endosulfan-beta, 4,4'DDT, kepone, endosulfate-sulfate, methoxychlor, mirex, 2,3,4 PCB, 2,2',4,5 PCB, 2,3,4,5 PCB and 2,2',3,3',6,6'PCB. After liquid-liquid or solid-liquid extraction, the extract of the sample was cleaned by high performance liquid chromatography (HPLC) and the fi rst eluted fraction was analysed by gas chromatography (GC) with mass spectrometry (MS) detector in tandem mode. To evaluate the validity of the method the following parameters were studied: linearity, detection limits, quantification limits, specificity, percentage recovery and precision. A study of the uncertainty associated with the analytical method was also carried out.
Chromatography, High Pressure Liquid↗
A review of chromatographic methods for the assessment of phospholipids in biological samples.
Phospholipids are important constituents of all living cell membranes. Lipidomics is a rapidly growing field that provides insight as to how specific phospholipids play roles in normal physiological and disease states. There are many analytical methods available for the qualitative and quantitative determination of phospholipids. This review provides a summary of the methods that were historically used such as thin layer chromatography, gas chromatography and high-performance liquid chromatography. In addition, an introduction to applications of interfacing these traditional chromatographic techniques with mass spectrometry is provided.
Animals↗
Application of fast atom bombardment mass spectrometry to biological samples: analysis of urinary metabolites of acetaminophen.
Fast atom bombardment (FAB) is useful for the characterization of all major metabolites of the analgesic acetaminophen (APAP). It is particularly useful for providing mass spectra of the polar glucuronide and sulfate conjugates which eluded identification by field desorption and other more conventional methods of ionization. A protocol is described for the use of FAB in the identification of urinary APAP metabolites isolated by reversed phase high-performance liquid chromatography (HPLC) following therapeutic dosages of the drug. A tentative set of recommendations for the off-line use of HPLC and FAB is directed towards solving problems encountered when using these two analytical techniques in concert. In addition, a method for calculating the signal to background ratio (S/B) for analyte peaks in FAB spectra from selected relative ion intensities is proposed. Examples are presented that show the potential of S/B as an empirical parameter for judging the quality of FAB spectra.
Acetaminophen↗
Isotope dilution mass spectrometry for procaine determination in biological samples.
A simple, rapid and sensitive method for procaine determination is described. Isotope dilution mass spectrometry with (15N)procaine as internal standard was used. The analysis was performed at 4000 resolution by selected ion monitoring with temperature programming. The sample was measured in underivatized form in the direct inlet system. The method shows good analytical parameters: linearity between 0 and 40 micrograms ml-1, good precision and accuracy. The method was applied to the in vitro pharmacokinetic study of the metabolism of procaine in liver homogenates of Wistar rats. The method is rapid, permitting about six samples to be run per hour. Sensitivity of the method permits analysis at a signal-to-noise ratio of 5:1.
Animals↗
Determination of terbutaline enantiomers in biological samples using liquid chromatography with coupled columns.
The purpose of this work was to develop and validate a method for the separation and determination of the enantiomers of terbutaline in plasma and intestinal juice. Terbutaline was extracted from plasma and intestinal juice by liquid-solid extraction on small C18 cartridges. The extract was then analyzed by coupled column liquid chromatography with amperometric detection. For chiral separation a beta-cyclodextrin phase was used. The within-day variation (Cv) on spiked plasma samples was in the range 0.8-6.4% at 3.8-33.8 nmol/liter for the (-)-enantiomer, and 2.6-23.0% at 1.3-11.3 nmol/liter for the (+)-enantiomer. The between-day variation on spiked plasma samples was 5.5% at 10.7 nmol/liter and 13.6% at 4.3 nmol/liter for the (-)-and (+)-enantiomers, respectively. The within-day variation for intestinal juice was in the range 0.7-1.5% at 5.6-30.0 mumol/liter for the (+)-enantiomer.
Body Fluids↗
Analysis of oxycodol and noroxycodol stereoisomers in biological samples by capillary electrophoresis.
A capillary electrophoresis (CE) method for the separation of the diastereoisomers of 6-oxycodol (6OCOL) and nor-6-oxycodol (N6OCOL), the 6-keto-reduced metabolites of oxycodone (OCOD) and noroxycodone (NOCOD), respectively, is reported and employed to assess the stereoselectivity of these metabolic steps in vivo, in vitro, and in chemical synthesis. CE in an untreated fused-silica capillary with acidic buffers containing 2-hydroxypropyl-beta-cyclodextrin, randomly sulfated beta-cyclodextrin, or single isomer heptakis(2,3-diacetyl-6-sulfato)-beta-cyclodextrin (HDAS-beta-CD) is shown to permit the simultaneous separation of the stereoisomers of 6OCOL and N6OCOL. A 100 mM phosphate buffer of pH 2.0 containing 2.05% w/v HDAS-beta-CD provides a medium for rapid analysis and unambiguous identification of these stereoisomers in solid-phase extracts of (i) urines stemming from patients under pharmacotherapy with OCOD, (ii) incubations of OCOD and NOCOD with human liver cytosol and the human liver S9 fraction, and (iii) after chemical synthesis from OCOD and NOCOD using NaBH(4). In all cases, alpha-N6OCOL is shown to be the predominant stereoisomer of N6OCOL. For 6OCOL, the same is true for in vitro formation and for chemical synthesis. In urine, however, beta-6OCOL is observed to be excreted in a higher amount than alpha-6OCOL. For the urinary alpha-/beta-isomer ratio of 6OCOL and N6OCOL, there are no differences between the data obtained for nonhydrolyzed and enzymatically hydrolyzed urines. The data document the stereoselectivity of the 6-keto-reduction of OCOD and NOCOD in man.
Electrophoresis, Capillary↗
Validated capillary electrophoresis assay for the simultaneous enantioselective determination of propafenone and its major metabolites in biological samples.
A robust, inexpensive, and fully validated CE method for the simultaneous determination of the enantiomers of propafenone (PPF), 5-hydroxy-propafenone (5OH-PPF) and N-despropyl-propafenone (NOR-PPF) in serum and in in vitro media is described. It is based upon liquid-liquid extraction at alkaline pH followed by analysis of the reconstituted extract by CE in presence of a pH 2.0 running buffer composed of 100 mM sodium phosphate, 19% methanol, and 0.6% highly sulfated beta-CD. For each compound, the S-enantiomers are shown to migrate ahead of their antipodes, and the overall run time is about 30 min. Enantiomer levels between 25 and 1000 ng/mL provide linear calibration graphs, and the LOD for all enantiomers is between 10 and 12 ng/mL. The assay is shown to be suitable for the determination of the enantiomers of PPF and its metabolites in in vitro incubations comprising human liver microsomes or single CYP450 enzymes (SUPERSOMES). Incubations with CYP2D6 SUPERSOMES revealed, for the first time, the simultaneous formation of the enantiomers of 5OH-PPF and NOR-PPF with that enzyme. CE data can be used for the evaluation of the enzymatic N-dealkylation and hydroxylation rates.
Anti-Arrhythmia Agents↗
Determination of opiates in biological samples through the analysis of heptafluorobutyric derivatives by gas chromatography/negative ion chemical ionization mass spectrometry.
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Analgesics, Opioid↗
Determination of total salicylates, phenacetin and-or total N-acetyl-p-aminophenol, and caffeine in biological samples and analgesic formulations.
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Acids↗
New and expedient determination of atenolol in biological samples.
A method is described for the GLC determination of atenolol BP in plasma and urine. Extraction is accomplished under dehydrating conditions, and interfering impurities are removed by using an acidified cyclohexane-isopropanol mixture (2:1) and charcoal-treated paper disks. The drug thus isolated appears to react more efficiently with heptafluorobutyric anhydride, increasing the sensitivity of GLC electron-capture analysis. Concentrations as low as 0.02 mug/ml were measured using 0.5-ml aliquots of plasma or 0.1 ml of urine. Amino alcohols such as atenolol may form hydrates or alcoholates, precluding complete derivatization with heptafluorobutyric anhydride.
Adrenergic beta-Antagonists↗
Determination of beta-carboline derivatives in biological samples by high-performance liquid chromatography with fluorescence detection.
An assay procedure for measuring plasma, urine, and feces levels of seven beta-carbolines and possible metabolites is described. The drugs are extracted with diethylether or, alternatively, with a commercially available automated extraction device after adding an appropriate internal standard. Separation from matrix constituents is performed by reversed-phase high-performance liquid chromatography (HPLC) followed by fluorescence detection. The carboxylic acid metabolites of the beta-carbolines have to be esterified before HPLC measurement. The detection limits are 0.2 ng/mL for beta-carbolines and 2 ng/mL for their metabolites. Plasma levels and pharmacokinetic parameters of six different beta-carbolines in healthy male volunteers following iv or po treatment are described. Total clearance ranged from 17 to 52 mL/min/kg and the terminal half-life ranged from 1 to 4 h. The absolute bioavailability exhibited a range from less than 1 to 61%.
Administration, Oral↗
Mercury levels in wheat and other cereals, oilseed and biological samples.
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Edible Grain↗