Quantitative determination of histamine metabolites by capillary gas chromatography

A method using capillary gas chromatography is described for the determination of histamine and eight of its basic and acid metabolites in a single biological sample of serum, urine, or gastric juice. Ion-exchange chromatography and extraction with organic solvents are used for isolation and purification, and gas chromatography for identification and quantitation. The heptafluorobutyryl derivatives of histamine and some basic metabolites are compatible with nitrogen-phosphorus and electron capture detection modes and offer an excellent sensitivity (detection limit 0.1 pmol with electron capture). The acid metabolites are quantitated after esterification. The linearity range, the sensitivity, a partial study of reproducibility and typical chromatograms show that the method is adaptable to a variety of applications.     

Recovery of volatile fatty acids from biological materials for direct analysis by gas chromatography

A simple and efficient methodology for preparing aqueous extracts of volatile fatty acids from biological materials, for direct analysis by gas chromatography is described. Peak areas and responses relative to n-butyric acid were used to calculate concentrations of the individual acids. An example is given for analysis of the volatile fatty acids found in the blood of the lugworm Aerinocola marina.     

Quantitative analysis of amineptine (S-1694) in biological samples by gas chromatography—mass fragmentography

A sensitive, specific method for the quantitative analysis of amineptine in rat blood and brain is described. After extraction and purification amineptine is detected by mass fragmentography, monitoring the fragment ion at $\text{m}\text{e}$ 192. The method allows the quantitative analysis of as little as 50 ng of amineptine per ml blood and 200 ng per g for brain.     

Quantitative analysis of the ring-hydroxylated metabolites of 2-fluorenylacetamide by gas-liquid chromatography

An analytical procedure is described for quantitative estimation of the C₅- and C₇-hydroxylated metabolites of the carcinogenic amide, 2-fluorenylacetamide. After incubation of 2-fluorenylacetamide in the presence of rat or hamster liver microsomes and a NADPH-generating system, these metabolites were extracted and derivatized with heptafluorobutyrylimidazole. Subsequent analysis by gas-liquid chromatography with electron-capture detection was sensitive enough for determination of the kinetic parameters of these hydroxylation reactions. The effects of pretreatment with 3-methylcholanthrene or 2,3-benzanthracene on these parameters were also studied.     

Comprehensive analysis of metabolites in Corynebacterium glutamicum by gas chromatography/mass spectrometry

An analytical method based on gas chromatography/mass spectrometry was developed for metabolome investigation of Corynebacterium glutamicum. For the first time a fast method for metabolic screening that can be automated is described for this organism. More than 1000 compounds could be detected per experiment, ca. 330 of those showed a peak area significantly above background. Out of these 164 compounds were identified so far, representing derivatives of 121 different metabolites, which were quantified in one sample. In spite of the different chemical nature of metabolites and high matrix content, a measurement reproducibility in the range of 6% error was achieved. The application of this method for the analysis of the adaptation of C. glutamicum to different growth conditions is demonstrated.     

Quantitative determination of 6-Oxo-PGF1 alpha in biological fluids by gas chromatography mass spectrometry

A selected ion monitoring method for the determination of 6-oxo-PGF1 alpha, the stable end-product of prostacyclin, in biological fluids has been developed. In this method, biosynthetically prepared [2H6]-6-oxo-PGF1 alpha is used as internal standard. The method involves extraction, thin-layer chromatography purification and derivatization into the methyl ester, methoxime, trimethylsilyl ether derivatives by carrying out the methoximation first. Quantitative gas chromatographic mass spectrometric analysis is performed in the electron impact mode by monitoring the [M - (TMSOH + CH3O)]+ fragment ions. The use of this method in the measurement of 6-oxo-PGF1 alpha in serous fluids and in incubation media of serous tissues is described.     

Simple method for analysis of diquat in biological fluids and tissues by high-performance liquid chromatography

A simple HPLC method has been described to quantify diquat in biological fluids and tissues. This method permits separation and quantification of diquat from blood, bile, urine, liver and kidney. It does not require special pretreatment of the samples prior to analysis, nor a specially prepared analytical column. Various concentrations of diquat were added (10–300 nmol/ml or g) to fluids or tissues. Analysis of blank samples revealed no substrates that interfere with diquat elution. Excellent recovery (95–105%) was obtained. Diquat (120 μmol/kg, i.v.) was injected to rats and quantified in bile, blood and liver. Concentration of diquat was higher in blood and bile than liver. Therefore, this method is applicable for quantification of diquat in toxicological samples, and may be used to determine structurally similar compounds such as paraquat.     

Quantitative analysis of urinary daidzein and equol by gas chromatography after solid-phase extraction and high-performance liquid chromatography

Daidzein and its main metabolite equol are isoflavone phytoestrogens. Several studies have suggested that intake of an isoflavone-rich diet may prevent hormone-related cancer and estrogen-related disorders (cardiovascular disease, osteoporosis and menopausal symptoms). To better understand the role of isoflavones in preventing such severe disease, several methods have been developed to measure these compounds in biological fluids. However, the analytical procedures to measure isoflavones are often time-consuming and require highly skilled technicians. In this paper we describe a method for urinary daidzein and equol measurement that combines solid phase extraction and HPLC purification before gas chromatographic determination. The specificity of the method was confirmed by the gas chromatography-mass spectrometry technique. The mean recovery of daidzein and equol was 94.6% and 97.0%, respectively. The repeatability of the method was in the range of 2.0-7.4% for daidzein and 1.3-4.9% for equol. A linear relationship between observed and expected values was found in the dilution (r2=0.9983 for daidzein; r2=0.9982 for equol) and addition (r2=0.9984 for daidzein; r2=0.9989 for equol) assays. The method is suitable to measure changes in the urinary excretion of isoflavones and to investigate urinary isoflavonoids as biomarkers of isoflavone exposure.     

Determination of desferrioxamine-available iron in biological tissues by high-pressure liquid chromatography

Intracellular iron loosely bound to proteins such as ferritin or in the form of low molecular weight chelates is available to catalyze adverse reactions such as the formation of reactive free radicals. A method to measure this small but important iron pool by utilizing the highly specific iron-chelator desferrioxamine is described. Following incubation of tissue fractions with desferrioxamine, the parent compound and its iron-bound form, ferrioxamine, are extracted using solid-phase cartridges and quantitated by reversed-phase HPLC using uv detection. Calculation of the ferrioxamine:desferrioxamine ratio and comparison with a standard curve constructed using a series of known iron concentrations allow the determination of micromolar amounts of desferrioxamine-available iron in biological samples.     

Quantitative analysis of albuterol in human plasma by combined gas chromatography chemical ionization mass spectrometry

A highly sensitive and specific quantitative assay for the determination of albuterol in human plasma, based on selected ion monitoring gas chromatography chemical ionization mass spectrometry, has been developed. The [MH]+ ions from the tri-TMS derivatives of albuterol (m/z 456) and the internal standard (2H3)albuterol (m/z 459), were assayed simultaneously by selected ion monitoring. The lower limit of quantitation is 0.25 ng ml-1 and the average assay precision (CV) for albuterol concentrations ranging from 0.25 ng ml-1 to 25 ng ml-1 is approximately 4%. This method is currently being employed for the routine quantitation of albuterol in plasma following the administration of doses therapeutically effective to man.