Quantitation of hexaprazol in human plasma and urine by capillary gas chromatography with nitrogen-sensitive detection

A selective and sensitive gas chromatographic assay for hexaprazol, a new antiulcer drug, in human plasma and urine has been developed. The method involves liquid-liquid extraction and capillary gas chromatography with nitrogen-sensitive detection. The limit of quantitation of plasma hexaprazol is ca. 25 ng/ml. The assay procedure permits the measurement of the levels of the unchanged drug following its clinical administration to humans.     

Determination of propafenone in biological fluids by fused-silica capillary gas chromatography using electron-capture detection

A gas-liquid chromatographic method with electron-capture detection using a capillary column with the inlet in the splitless injection mode is reported for the assay of propafenone. A 25 m X 0.31 mm cross-linked, 5% phenylmethylsilicone-coated fused-silica capillary column was employed for all analyses. The present method provides improved selectivity and sensitivity over other existing gas chromatographic and high-performance liquid chromatographic (HPLC) methods. Linearity was observed in the ranges 2.5-50 and 10-100 ng/ml. The coefficient of variation was found to be less than 10% over the concentration ranges studied. Application of the developed method is demonstrated by measuring serum propafenone concentrations over 24 h in a normal healthy volunteer after a single oral dose of propafenone and by measuring trough plasma propafenone concentrations at steady state in patients receiving this new antiarrhythmic drug. Validity of the present method is further demonstrated by comparison of analytical results obtained from measurement of patient samples using a modified published HPLC method.     

Determination of a new blood glucose-lowering agent in biological fluids by capillary gas chromatography using electron-capture detection

A gas chromatographic method for the determination of 5-(4-chlorophenyl)-2-[(4-methylphenyl)sulphonyl]-4-pentynoic acid (I) in plasma (serum) and urine has been developed. After an extraction process, the cleaned-up organic extract was derivatized with diazomethane at ambient temperature. Results are evaluated from peak-height ratios with respect to the appropriate internal standard. The detection limit following extraction of a 1-ml plasma sample is about 20 ng/ml.     

Determination of ritodrine in biological fluids of the pregnant sheep by fused-silica capillary gas chromatography using electron-capture detection

A sensitive and selective gas chromatographic assay method employing splitless injection, fused-silica capillary columns and electron-capture detection is reported for the quantitation of the tocolytic drug, ritodrine, in a variety of biological fluids obtained from the pregnant ewe and fetus. This method has improved sensitivity and selectivity over previously published assay procedures. A 25 m x 0.31 mm I.D., cross-linked 5% phenylmethylsilicone, fused-silica capillary column was employed for all analyses. Linearity of response was observed over the range 2.5-75 ng of ritodrine base per 0.05-0.5 ml of biological fluid, representing approximately 1-75 pg at the detector. The coefficient of variation was less than 10% over the range 2.5-75 ng of added ritodrine. The minimum quantifiable amount is approximately 2.5 ng from a 0.5-ml biological fluid sample. Applicability of this method to biological fluids, obtained from ovine subjects, is demonstrated by the analysis of samples obtained during the course of ritodrine placental transfer studies.     

Simultaneous determination of nicotine and cotinine in plasma by capillary gas liquid chromatography with nitrogen-sensitive detection

Conclusion By the use of structural analogues of nicotine and cotinine as internal standards, the elimination of environmental sources of contamination and an exact clean-up procedure, we were able to develop a rapid and sensitive method which has acceptable accuracy and precision over the concentration range necessary in pharmacokinetic studies.

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Gleichzeitige Bestimmung von Nicotin und Cotinin in Plasma mit Hilfe der Capillar-Gas-Chromatographie

     

Determination of hydrazine in biofluids by capillary gas chromatography with nitrogen-sensitive or mass spectrometric detection.

Plasma and liver levels of hydrazine were determined at 10, 30, 90 and 270 min in rats given 0.09, 0.27, 0.84 and 2.53 mmol of hydrazine per kg body weight orally by capillary gas chromatography-mass spectrometry of its pentafluorobenzaldehyde adduct (DFBA, m/z 388) using selected ion monitoring with 15N2-labelled hydrazine as the internal standard (adduct, m/z 390). The mean half-life for hydrazine in the plasma was approximately 2 h but varied with dose. Urinary excretion (0-24 h) of hydrazine and its metabolite acetylhydrazine were determined employing nitrogen-phosphorus detection of the adducts utilising a novel internal standard, pentafluorophenylhydrazine, the adduct of which structurally resembles DFBA. The fraction of the original dose excreted as hydrazine (and acetylhydrazine) declined with increasing dose.     

Quantification of amitriptyline, nortriptyline, and 10-hydroxy metabolite isomers in plasma by capillary gas chromatography with nitrogen-sensitive detection

A selective, sensitive method for the determination of amitriptyline and its metabolites is described. This method involves liquid-liquid extraction and capillary gas chromatography with nitrogen-sensitive detection. The detection limits of amitriptyline, nortriptyline, 10-hydroxy(E)amitriptyline, 10-hydroxy(E)nortriptyline, and 10-hydroxy(Z)nortriptyline were slightly less than 0.5 ng/ml in 1.0-ml plasma samples. The coefficients of variation for within-run and between-run analyses of samples containing 100 ng/ml were less than 12% and 9%, respectively. The method offers rapid analysis of individual isomers, increased sensitivity over high-performance liquid chromatographic methodology and the conveniences of the gas chromatographic technique.     

Determination of butaperazine in biological fluids by gas chromatography using nitrogen specific detection system.

A simple and sensitive gas chromatographic method for the quantitative determination of butaperazine in biological fluids is described. The use of a nitrogen specific detector reduces the number of interfering peaks, thereby increasing the number of samples that can be analyzed. When butaperazine is extracted from 2 ml of plasma, the coefficient of variation is 7.4% over the concentration range of 5-180 ng/ml. The method was used to measure the levels in plasma and red blood cells in schizophrenic patients treated with butaperazine. It was also extended to measure butaperazine levels in rat red blood cells, plasma, liver, and brain after intraperitoneal injection (15 mg/kg).     

Quantitation of p-aminohippuric acid in biological fluids by high-performance liquid chromatography and dual-wavelength ultraviolet detection

A modification of the method of Verbeke [J. Chromatogr., 177 (1979) 69] is presented. The fatty tissue is dissolved in hexane, partitioned against methanol-sodium acetate buffer (pH 5.2) and extracted with dichloromethane. The crude extract is then purified on a disposable C18 column. The final extract together with a set of reference compounds is spotted on two opposite sides of a high-performance thin-layer chromatographic plate (10 X 10 cm), which is developed with two different eluents in two opposite directions. This mode of operation has the advantage that more reference compounds can be spotted and that the identification is based on two independent chromatographic runs. Also the total analysis time is decreased.     

Determination of diphenhydramine in biological fluids by capillary gas chromatography using nitrogen-phosphorus detection. Application to placental transfer studies in pregnant sheep

A nitrogen-phosphorus detection-gas chromatographic method, which provides improved sensitivity and selectivity for diphenhydramine, is reported. A 25 m X 0.31 mm cross-linked, 5% phenylmethyl silicone-coated fused-silica capillary column (film thickness 0.52 micron) was used for all analyses. The splitless capillary injection mode was employed with a 2-microliter sample being introduced by an automatic liquid sampler. Standard curves, using orphenadrine as an internal standard, were linear in the range 2-320 ng of diphenhydramine per 0.5 ml of sheep plasma. This represents an amount of diphenhydramine from ca. 40 pg to 6.4 ng at the detector. Chromatographic separation of diphenhydramine and orphenadrine was excellent, with no interference from endogenous plasma constituents. Applicability of the method was demonstrated by a placental transfer study in a chronically instrumented pregnant sheep following a 100 mg intravenous injection of diphenhydramine to the ewe.     

Multiresidue determination of organophosphorus and organochlorine pesticides in human biological fluids by capillary gas chromatography

Two multiresidue analytical methods for the simultaneous determination of organophosphorus and organochlorine pesticides in human urine and serum samples are described. The first approach is based on liquid–liquid microextraction with dichloromethane, and the second uses solid-phase extraction with C₁₈. In both methods, the extracts are analyzed by capillary gas chromatography using nitrogen-phosphorus detection (NPD) and electron-capture detection (ECD). Limits of detection of the overall procedure of analysis are at the low ng mL^–1 level. Stability experiments have been performed with spiked urine and serum samples stored at 4?°C for 1 month. Finally, the solid-phase extraction procedure was applied to real-world samples. Quantification was performed by NPD or ECD, and peak identity was confirmed by use of mass-selective detection (MSD).     

Multiresidue determination of organophosphorus and organochlorine pesticides in human biological fluids by capillary gas chromatography

Two multiresidue analytical methods for the simultaneous determination of organophosphorus and organochlorine pesticides in human urine and serum samples are described. The first approach is based on liquid-liquid microextraction with dichloromethane, and the second uses solid-phase extraction with C18. In both methods, the extracts are analyzed by capillary gas chromatography using nitrogen-phosphorus detection (NPD) and electron-capture detection (ECD). Limits of detection of the overall procedure of analysis are at the low ng mL(-1) level. Stability experiments have been performed with spiked urine and serum samples stored at 4 degrees C for 1 month. Finally, the solid-phase extraction procedure was applied to real-world samples. Quantification was performed by NPD or ECD, and peak identity was confirmed by use of mass-selective detection (MSD).     

Assay of ambroxol in biological fluids by capillary gas-liquid chromatography

A sensitive and rapid method for the determination of ambroxol in biological fluids is described. It comprises a single extraction step, derivatization and selective determination with capillary gas-liquid chromatography (in split-mode) and electron-capture detection. The limit of quantification in plasma is ca. 3 ng/ml. The method is applied to the pharmacokinetics of ambroxol in humans.     

Determination of muscle relaxants pancuronium and vecuronium bromide by capillary electrophoresis with capacitively coupled contactless conductivity detection

A novel capillary electrophoretic method for the separation of pancuronium (PM) and vecuronium (VM) ions utilizing capacitively coupled contactless conductivity detection was devised and validated. The separation was carried out in bare fused-silica capillaries (50 μm id, 75/45 cm) at 25°C. Optimal BGE was 50 mM borate buffer of pH 9.5 containing 12.5 mg/mL of (2-hydoxypropyl)-γ-CD. The samples were injected hydrodynamically at 1000 mbar for 3 s. Separation was performed at +30 kV. Under such conditions the PM and VM were base-line resolved and the separation took < 4 min. For quantification phenyltrimethylammonium iodide was used as internal standard. Calibration curves were linear for both pancuronium bromide (PMB) and vecuronium bromide (VMB) in the range 25-250 μg/mL with r> 0.9968. The limits of detection were 7 and 6?μg/mL for PMB and VMB, respectively. The accuracy tested by recovery experiment at three concentration levels of added PMB and VMB was satisfactory (95.7-102.7%, n =3, with RSD < 2.61%). The method was successfully applied to the assay of PMB and VMB in commercial injection solutions.     

Quantitation of chlordiazepoxide and its metabolites in biological fluids by thin-layer chromatography.

Chlordiazepoxide and its 4 major metabolites were assayed after separation by thin-layer chromatography following extraction from biological fluids. The compounds become intensely fluorescent in the presence of red, fuming nitric acid. The resulting compounds are quantitated with a spectrodensitometer with a fluorescent attachment. The sensitivity varies between 0.05 and 0.1 microgram. The coefficient of variation is 1.4% for assays in urine and 6.4% in serum.     

Element-selective detection using capillary gas chromatography with atomic emission detection

Capillary GC coupled to an atomic emission detector (AED) provides a powerful new hyphenated technique for the separation and characterization of complex mixtures and compounds. The AED provides simultaneous and truly specific multi-element detection. The specificity of detection reduces the need for the complex sample pretreatment procedures which are necessary to reduce the interference from co-eluted substances which is experienced with detectors such as the FID and the ECD. A range of environmentally significant problems has been studied, including PCB analysis, the characterization of the reaction products of a novel waste treatment process, and the profiling of sulfur-containing species formed by the pyrolysis of various types of coal.     

Determination of methylmercury in biological samples by capillary gas chromatography with electron capture detection

A precise and accurate method has been developed for the determination of methylmercury in biological material using capillary gas chromatography with electron-capture detection. Homogenized fish or mussel samples were digested with acid, spiked with ethylmercury chloride as an internal standard and extracted with toluene. After treatment of the solvent extract with sodium thiosulphate and cupric bromide the alkylmercurials were extracted into benzene as their bromide derivatives and analyzed using an OV-275 coated glass capillary column. The detection limit of the method for methylmercury was 5 g/kg tissue.