Glass Capillary Gas Chromatography-mass Spectrometry Research Articles

Determination of plasma testosterone by mass fragmentography using [3,4- 13C]testosterone as an internal standard

The combination of glass capillary gas chromatography—mass spectrometry is especially suitable for the recognition of compounds. The use of [3,4- 13C]testosterone as internal standard, mass fragmentography and isotope ratio measurement have been applied to the quantitative determination of testosterone in plasma. This paper describes the method, using tert.-butyldimethylsilylmethoxime and di-heptafluorobutyrate derivatives. The calibration graph in isotopic dilution is examined. The results obtained are compared with the results obtained by radioimmunoassay. The sensitivity of the method is judged from the lower limit of detection: 4.5 pg. The precision, and inter- and intra-assay are calculated.

Glass capillary gas chromatography—mass spectrometry of mixtures of isomeric halogenated esters of carboxylic acids

The possibilities of glass capillary column gas chromatography—mass spectrometry for separation and identification of isomeric halogenated esters (halogen substituent either in the alcohol or acid chain) were invetigated. Three stationary phases, OV-101, SE-54 and SP-1000, were tested. The influence of the stationary phase and the structure of the isomers on retention is discussed.

Gas chromatography—mass spectrometry of trimethylsilyl pteridines

The trimethylsilyl derivatives of about 70 naturally occurring as well as synthetic pteridines have been investigated by glass capillary gas chromatography—mass spectrometry. On the apolar SE-52 phase used, the retention time of the compounds, tabulated in methylene units, was influenced more by the polarity than by the molecular weight. The electron-impact mass spectra of most compounds showed intense ▪ and ▪—15 ions and characteristic fragmentation patterns of 5,6,7,8-tetrahydropteridines, 7,8-dihydropteridines, sepia analogues and fully oxidized pteridines. The methylene units, together with the five most intense fragments tabulated, provide a good basis for the identification of these compounds in biological samples and for structure elucidation of unknown pteridines.

Analysis of chlorianted guaiacols in spent bleac liquor from a pulp mill

Extraction stage spent bleach liquor from a pine kraft pulp mill was studied for its content of chlorinated guaiacols. The compounds were analysed by a method involving extraction with diethyl ether and glass capillary gas chromatography of their acetyl derivatives using a flame ionization detector and SE-30 and OV-351 quartz capillary columns. The structures of the components were confirmed by glass capillary gas chromatography—mass spectrometry. In quantitations both external and internal standard methods were used. All possible chlorinated guaiacols were used as refernce substances. The guaiacol concentrations varied from ca. 0.004 to 1.57 ppm, the total concentration being about 4ppm. 3,4,5-Trichloroguaiacol was present in the highest concentration (1.57 ppm). Other major components were tetrachloroguaiacol (1.21 ppm), 4,5-dichloroguaiacol (0.42 ppm) and 4,5,6-trichloroguaiacol (0.32 ppm). The identifies and quantities of 4-chloro-, 5-chloro-, 3,4-dichloro-, 4,6-dichloro- and 3,4,6-trichloroguaiacol were also determined.

Analysis of neutral steroid sulfates by glass capillary gas chromatography-mass spectrometry (GC-MS) from blood of a patient with paraquat poisoning

The chemical analysis of neutral steroid sulfates by glass capillary gas chromatography -mass spectrometry (GC-MS) from the blood of a young girl with acute suicidal paraquat poisoning is described. The steroids had been extracted from an XAD-filter used for immediate hemofiltration treatment of the patient. The steroids analyzed were isomers of known blood and urine components without unusual substituents. It can be concluded that oral intake of paraquat in even large amounts does not cause significant disturbances of steroid metabolism, at least not in the acute state of intoxication.

Multi-component analyses of human body fluids and tissues in health and disease using capillary gas chromatography-mass spectrometry and high-resolution two-dimensional electrophoresis

Glass capillary gas chromatography-mass spectrometry and high resolution two-dimensional electrophoresis have been used in combination to achieve multi-component analyses of human serum, urine, cerebrospinal fluid and various tumours. The analytical system covers both low- and high-molecular-weight constituents, that is, metabolites and proteins. Over 1000 compounds can be separated in a single sample of a few milligrams. The techniques have been used to study changes in the biochemical composition of body fluids and tissues in different human diseases: metabolic disorder, neurological disorders and certain types of cancer. The new multi-component analytical approach, now in its early stages, may have considerable potential in biomedical research and diagnosis.

Capillary gas chromatographic—mass spectrometric profiles of trimethylsilyl derivatives of organic acids from amniotic fluids of different gestational age

Amniotic fluid from different gestational age patients was partitioned into neutral, acidic and basic fractions. The organic acids were trimethylsilylated and analyzed by glass capillary gas chromatography—mass spectrometry. A marked difference in the level of hippuric acid was observed between samples from early (15–22 weeks) and late (30–38.5 weeks) pregnancy. This difference probably reflects the degree of maturity in the fetal liver and kidney. The procedures establish amniotic fluid profiles of substances of varying gestational age and should be useful in determining alterations caused by diseases.

Instrumental potentialities for the determination of anabolic agents in edible animal products and body fluids

Numerous steroid hormones such as androgens, estrogens and gestagens as well as their synthetic analogues are well known to stimulate the biosynthesis of proteins. Due to this anabolic effect they are widely used as growth-promoting agents in animal production, the most frequently applied compounds being the estrogens and in particular the non-steroidal stilbene derivatives. With only a few exceptions these compounds also exhibit hormone-like activities so that their application is strictly regulated or even banned. For the effective control of these regulations at present two different analytical methodologies with high precision and sensitivity are available and well introduced. First, the immunological assays like radioimmunoassay (RIA) [4] or enzymeimmunoassay (EIA) have to be mentioned, which are extremely sensitive (down to the 50 pg/g level) and quite easily to perform. However, their application is restricted to those drugs, for which specific antisera have been developed and which are not expected to undergo an extensive metabolism (estradiol, diethylstilbestrol, trenbolone and methandienone). The second methodology is an instrumental approach, based on advanced techniques of gas chromatography (GC), highperformance liquid chromatography (HPLC) and glass-capillary gas chromatography-mass spectrometry (GC-MS) [1]. In general, up to now, these methods are not as sensitive as the immunoassays but they are capable of detecting a wide spectrum of anabolic drugs together with their potential metabolites simultaneously, thus being most suitable for routine screening procedures. By introducing selective detection systems (multiple ion detection, voltammetric detection) they may be optimized for determinations in the upper pg/g range with a relative standard deviation of _+ 10 %. To achieve these limits in practical applications a number of method-specific requirements concerning sample preparation and clean-up have to be considered which are summarized in brief below.

High-resolution gas chromatography-mass spectrometry of the methyl esters of organic acids from uremic hemofiltrates

The organic acid fraction of hemofiltrates was investigated in the form of methylates by glass capillary gas chromatography-mass spectrometry. The pattern obtained is similar to that of urinary organic acid methylates from healthy individuals. A marked difference was noted for N-phenylacetyl-α-aminoglutarimide, present in hemofiltrate at levels 50–100 times higher than those in urine. Analysis of hemofiltrate samples taken at different times during a hemofiltration with post-dilution technique revealed that the hemofiltrate concentration of most compounds was drastically reduced during the course of the hemofiltration treatment. Compared to the other compounds, the reduction in hemofiltrate concentration of N-phenylacetyl-α-aminoglutarimide was extremely rapid.

Determination of organic contaminants by the Grob closed‐loop‐stripping technique

A modified Grob closed‐loop‐stripping device is currently being used to concentrate organic contaminants from drinking water. The identification and quantification of organic contaminants at the nanogran per litre (part‐per‐trillion) level are accomplished by a computerized glass capillary gas chromatography–mass spectrometry system. Applications of closed‐loop‐stripping analysis (CLSA) for monitoring water by water utilities, for studying the use and effects of alternative disinfectants in drinking water, and for providing data on the removal of organic contaminants from water by granular activated carbon (GAC) treatment are discussed. An attempt to validate the method using statistical computations is also included.

Trennung und charakterisierung saurer harnbestandteile

Separation and characterization of acidic urine constituents The acidic compounds of urine were separated by thin-layer chromatography in eight fractions. Each fraction was investigated separately by the combination glass capillary gas chromatography—mass spectrometry. About 500 compounds were detected, 2/5 of these could be characterized by their mass spectra. Retention data and key fragments of the mass spectra were tabulated. Many of the detected compounds are still unknown.

Sterenes in surface sediments from the southwest African shelf and slope

Surface sediment samples collected from the southwest African (Namibian) shelf and slope have been analyzed for their hydrocarbon content. In the surface samples a class of olefinic isoprenoid hydrocarbons, the Sterenes, have been found to represent 20–40% of the total hydrocarbons. To the best of our knowledge Sterenes have not been reported in surface marine sediments in such high concentrations. Cholest-2-ene, cholestadiene, cholestatriene, 24-methylcholest-2-ene, 24-methylcholestadiene, 24-ethylcholest-2-ene and 24-ethylcholestadiene were found in the sediments and identified by high resolution glass capillary gas chromatography-mass spectrometry. The formation of Sterenes from sterols via microbiological processes or chemical auto-oxidation, followed by subsequent dehydration mechanisms and double bond isomerizations. is postulated. It appears that there are highly unique environments in the upwelled area off southwest Africa providing the microbiological and chemical conditions for rapid diagenesis of the sterols within a time scale of 100 yr or less.

Analysis of unconjugated steroids in plasma by liquid-gel chromatography and glass capillary gas chromatography-mass spectrometry

A method is described for analysis of metabolic profiles of unconjugated steroids in plasma. After extraction by Amberlite XAD-2 at 64°, the steroids are purified by filtration through a 0.5 g column of sulphoethyl Sephadex LH-20 in methanol, and by chromatography on a 0.5 g column of triethyl-aminohydroxypropyl-hydroxyalkyl Sephadex LH-20. The latter column is used in a reversed-phase system which separates neutral steroids as a group from less polar lipids, and yields phenolic steroids in a separate fraction. The neutral steroids are converted into MO-TMS derivatives which are purified by rapid filtration through a 0.25 g column of Lipidex 5000 in hexane containing pyridine, hexameth-yidisilazane and dimethoxypropane to prevent hydrolysis of TMS ethers. Estrogens are converted into TMS ethers. The recoveries of added [ 3H]-labelled neutral steroids and estrogens are about 85%. Sample sizes corresponding to 1–2 ml plasma can be injected onto glass capillary columns. The derivatives are analyzed by repetitive scanning GC-MS using a glass capillary column connected via a single-stage adjustable jet separator. Metal surfaces are deactivated with water glass and benzyltri-phenylphosphonium chloride, and a Teflon coupling device is used for glass-glass capillary connections. Characterization and quantitation of steroids is based on computer construction of fragment ion current chromatograms. When the method was applied to the analysis of unconjugated steroids in plasma from pregnant women, 27 steroids in the concentration range 1–300 ng/ml could be identified. The 13 major pregnane derivatives were quantitated. The coefficients of variation were 5–13% when 5 analyses of the same sample were performed.

Effect of heating time on volatile composition of canned pork meat

Volatiles from samples of ground pork meat, subject to 10, 20, 30 and 40 min heating at 121°C, were isolated by trapping on Tenax GC and Porapak Q. Essences were compared on wall-coated open-tubular glass capillary columns and analysed by glass capillary gas chromatography-mass spectrometry. Low molecular weight alcohols, many with branched-chain skeletons, mercaptans and cyclic products, were among the compounds identified. The amount of volatiles present appeared to correlate well with the heating time to which the sample had been subjected.

Untersuchung der Steroidausscheidung im Neugeborenen-Urin mit der Kombination Glaskapillargaschromatograph?Massenspektrometer

The steroids in the urine of newborn babies were investigated by glass capillary gas chromatography-mass spectrometry. In addition to those steroids already known, the compounds1, 5, 37, and43–54 were identified as steroidal components of the urine of the newborn. Of special interest is the occurrence of steroids5, 37, and46 with an oxygen function at position11, of those with a 3-oxo-4-ene structure,44, 50, 53, 54, and of 3β-hydroxy-androsta-5,7-diene,51.