A sensitive gas chromatographic method for determination of protein-associated sulfur

A sensitive method for the determination of elemental sulfur bound to serum albumin and other proteins has been devised. The sample is treated with a hexane solution of triphenylphosphine, and the triphenylphosphine sulfide formed is determined by gas chromatography with a flame photometric sulfur detector. The detection limit of the method is 0.3 microM albumin-associated sulfur. Protein-associated sulfur was not detected in plasma from rats or normal human beings, findings that do not support an earlier suggested transport function of serum albumin for sulfur. Significant amounts of protein-associated sulfur, however, were found in certain rat tissues.     

气相色谱法测定生物制品中苯酚含量

本文采用气相色谱法测定了几种生物制品中苯酚含量。样品无需进一步处理,加入内标液后直接上柱测定,色谱峰形良好,线性范围宽,平均回收率和变异系数分别为１０１．８％ 和１．０８５％ ,最小检测限为１０ μｇ／ｍ ｌ,本法操作简单,样品用量少,可作为测定生物制品中苯酚含量的一种常规方法。     

A rapid method for gas chromatographic analysis of mono- and disaccharide mixtures

A technique is described for the rapid gas-liquid chromatographic analysis of mixtures of carbohydrate trimethylsilyl ethers prepared at mutarotation equilibrium. A mixture containing arabinose, ribose, xylose, fructose, glucose, galactose, mannose, sucrose, maltose, and cellobiose can be determined in less than 16 min using high-rate temperature programming.     

A gas chromatographic method for the determination of inositol monophosphates in rat brain

Regional levels of cerebral inositol-1-phosphate (Ins1P), an intermediate in phosphoinositide (PI) cycle, were readily detected with a new gas chromatographic (GC) method. GC analysis of trimethylsilyated Ins1P and myo-inositol-2-phosphate with a fused silica capillary SE-30 column and flame ionization detection was linear at picomolar range (pmol/l) with a sensitivity to a level of 2 pmol. Also, inositol monophosphates and glucose-6-phosphate are separated in unstimulated brain tissue. The mean recovery of the method is 98±5.2%. Ins 1P levels were higher in frontal than in caudal regions in control brains. Lithium treatment increased the levels of Ins1P throughout the brain but mostly in frontal brain regions and in the hippocampus. The present GC assay to measure the accumulation of Ins1P, an index for the activity of PI signalling, may be suitable for exploring regional differences in cerebral receptor-coupled PI signalling in vivo.     

Stereospecific gas chromatographic method for determination of methadone in serum.

rac-Methadone is used clinically for the chronic maintenance treatment of heroin addiction and for the relief of pain. As the pharmacological activity of methadone is due primarily to the (-)-(R)-enantiomer, stereospecific measurements of methadone serum concentrations in methadone-treated patients are expected to be more relevant for clinical studies than earlier described total drug measurements. This study describes a stereospecific gas chromatographic (GC) method for the determination of methadone in serum. The extracted methadone was derivatizised with (-)-menthyl chloroformate. The diastereometric derivatives were analysed by GC on a capillary column and detected with a nitrogen-phosphorus detector. The resolution factor obtained for the methadone enantiomers was 1.1 with a relatively short time of analysis (30 min). By analysing the pure (-)-(R)-enantiomer, no racemization was seen during the analysis. The lower limit of quantitation was 75 nmol/l for each enantiomer. Measurements of the ratio between (-)-(R)- and (+)-(S)-methadone concentrations in serum from five methadone-treated patients showed interindividual differences (range 0.5-1.1). The patient results correlated well with those from another GC method measuring total methadone.     

A method for equilibration chamber sampling and gas chromatographic analysis of the soil atmosphere

The method includes sampling of gases from an equilibration chamber permanently installed in the soil, transferring the sample to laboratory and subsequent measurement by gas chromatography. The equilibration chamber allows sampling of the gas phase both above and below the groundwater level, which is a major advantage. After significant concentration changes in non-saturated soils, gases in chambers regain equilibrium with the surrounding soils within 1–2 days. In the most unfavourable equilibration situations,i.e. in mineral subsoils with stagnant groundwater and very low biological activity, 90% equilibrium is attained in about 15 days. N₂, O₂+Ar, CO₂, CH₄, N₂O, H₂ and Ne, are measured on a series/bypass multi-column system, followed by a thermal conductivity detector.     

Sensitive gas chromatographic method for determination of mercapturic acids in human urine

A method was developed for sensitive determination of the specific benzene metabolite S-phenylmercapturic acid and the corresponding toluene metabolite S-benzylmercapturic acid in human urine for non-occupational and occupational exposure. The sample preparation procedure consists of liquid extraction of urine samples followed by precolumn derivatization and a clean-up by normal-phase HPLC. Determination of analytes occurs by gas chromatography with electron-capture detection. With this highly sensitive method (detection limits 60 and 65 ng/l, respectively) urinary S-phenylmercapturic and S-benzylmercapturic acid concentrations for non-occupationally exposed persons (e.g. non-smokers) can be measured precisely in one chromatographic run. Validation of the method occured by comparison with a HPLC method we have published recently.     

Improved gas chromatographic method for the determination of nicotine and cotinine in biologic fluids

Improved methods have been developed for the determination of nicotine and its major metabolite, cotinine, in blood, plasma, and urine samples. These methods utilize gas chromatography with alkali flame ionization (nitrogen—phosphorus) detection and structural analogs of nicotine and cotinine as internal standards.     

Sensitive gas chromatographic method for the determination of cinnarizine and flunarizine in biological samples

A sensitive method has been developed for the determination of the vasoactive compounds cinnarizine and flunarizine in plasma, urine and milk samples from man and animals. The procedure involves the extraction of the drugs and their internal standard from the biological samples at alkaline pH, back-extraction into sulphuric acid and re-extraction into the organic phase (heptane—isoamyl alcohol).The analyses were carried out by gas chromatography using a nitrogen-selective thermionic specific detector. The detection limit was 0.5 ng/ml of biological fluid and extraction recoveries were sufficiently high (87–94%).The method was applied to plasma samples from bioavailability studies of both cinnarizine and flunarizine in healthy volunteers, and to plasma, urine and milk samples from flunarizine-treated dogs.     

A gas chromatographic method for the determination of aldose and uronic Acid constituents of plant cell wall polysaccharides

A major problem in determining the composition of plant cell wall polysaccharides has been the lack of a suitable method for accurately determining the amounts of galacturonic and glucuronic acids in such polymers. A gas chromatographic method for aldose analysis has been extended to include uronic acids. Cell wall polysaccharides are depolymerized by acid hydrolysis followed by treatment with a mixture of fungal polysaccharide-degrading enzymes. The aldoses and uronic acids released by this treatment are then reduced with NaBH₄ to alditols and aldonic acids, respectively. The aldonic acids are separated from the alditols with Dowex-1 (acetate form) ion exchange resin, which binds the aldonic acids. The alditols, which do not bind, are washed from the resin and then acetylated with acetic anhydride to form the alditol acetate derivatives. The aldonic acids are eluted from the resin with HCl. After the resin has been removed, the HCl solution of the aldonic acids is evaporated to dryness, converting the aldonic acids to aldonolactones. The aldonolactones are reduced with NaBH₄ to the corresponding alditols, dried and acetylated. The resulting alditol acetate mixtures produced from the aldoses and those from the uronic acids are analyzed separately by gas chromatography. This technique has been used to determine the changes in composition of Red Kidney bean (Phaseolus vulgaris) hypocotyl cell walls during growth, and to compare the cell wall polysaccharide compositions of several parts of bean plants. Galacturonic acid is found to be a major component of all the cell wall polysaccharides examined.