Column Gas Chromatography-mass Spectrometry Research Articles

Sulphur heterocycles in coal-derived products: Relation between structure and abundance

Sulphur heterocycles in a coal tar and in a coal liquid vacuum residue were isolated by ligand exchange chromatography using PdCl 2 on silica gel. Subsequent fractions were analysed by capillary column gas chromatography and gas chromatography-mass spectrometry. Two new selective stationary phases (a smectic liquid-crystalline polysiloxane and a biphenyl polysiloxane), as well as a methylpolysiloxane, were used to resolve the numerous isomers. All major sulphur heterocycles with 3–6 rings were identified by comparison of retention times of mixture components with those of standard reference compounds. The structures and relative abundances of the major sulphur heterocycles were analogous to those of the major polycyclic aromatic hydrocarbons in the same or similar samples.

Isolation of two novel E prostaglandins in human seminal fluid.

cis-8,11,14,17-[1-14C]Eicosatetraenoic acid was incubated with microsomes of ram seminal vesicles and 1 mM glutathione for 3 min at 37 degrees C. The main metabolite was identified as 17,18-dehydroprostaglandin E1 by capillary column gas chromatography-mass spectrometry. Human seminal fluid was analyzed for the presence of 17,18-dehydroprostaglandin E1 and prostaglandin E3. Whereas prostaglandin E3 could be demonstrated by capillary gas chromatography-mass spectrometry, 17,18-dehydroprostaglandin E1 could not be found under these conditions. However, human seminal fluid contained two compounds with a similar polarity on reversed phase high performance liquid chromatography as 17,18-dehydroprostaglandin E1 and prostaglandin E3. The two compounds were identified as 18,19-dehydroprostaglandin E1 and 18,19-dehydroprostaglandin E2 by gas chromatography-mass spectrometry, by UV analysis after conversion to the corresponding prostaglandin B compounds, and by ozonolysis. The amount of each of the two prostaglandins in human seminal fluid seemed to be in the same order of magnitude as the amount of prostaglandin E3.

Simultaneous quantitative measurement of fourteen adrenal steroids by capillary column gas chromatographymass spectrometry, and its clinical application

Until now, there has been little work covering all of the main native adrenal-cortical steroids in blood. We therefore established a method for the simultaneous quantitative measurement of 14 native adrenal-cortical steroids, which involves capillary column gas chromatographymass spectrometry (GCMS). Serum steroids were purified from serum with the Extrelut® mini-column and then converted into stable derivatives for GCMS by a combination of boronic cyclization and trimethylsilyl and methyloxime derivatization. The sensitivities (with a signal-to-noise ratio ⩾ 7) of our GCMS method ranged from 0.1 to 1.0 ng/ml of serum, and the coefficients of variation of intra- and inter-assays were 19% for each steroid. Our newly devised method involving a capillary column GCMS system has been proven to be a simple and suitable method for a diagnosis requiring simultaneous detection of many native adrenal steroids in clinical practice. the analysis time is only 4 h.

Determination of bucindolol and its major metabolites in plasma by capillary gas chromatography—mass spectrometry

A method for determining bucindolol, a deuterated analogue and two metabolites in plasma samples is described. Analytes are obtained from plasma by liquid extraction of 1 ml of plasma at pH 10.5 with 7 ml of peroxide-free ether—hexane (4:1). Following derivatization with 50 μl of N-methyl-N-trimethylsilyl trifluoroacetamide—pyridine (1:1) for 20 min at 65°C the samples are analyzed by capillary column gas chromatography—mass spectrometry with selected-ion monitoring. Quantification is linear over the range 2–500 ng/ml. Single-day precision was typically 6.2% or better for bucindolol and 13% or better for the metabolites.

Determination of quinupramin in plasma and urine by capillary column gas chromatography—mass spectrometry

Determination of quinupramin in plasma and urine by capillary column gas chromatography—mass spectrometry

Simultaneous quantitation of morphine, monobutanoylmorphine and dibutanoylmorphine using short capillary column gas chromatography-mass spectrometry.

An assay procedure for quantitating 3,6-dibutanoylmorphine, a morphine diester, and its metabolites, 6-monobutanoylmorphine and morphine, has been developed. The method involves a one-step extraction from various biological media, gas chromatographic separation using a short methylsilicone capillary column and sensitive and selective quantitation by single ion monitoring mass spectrometry. The use of short capillary column GC-MS allowed the rapid separation of compounds with dissimilar retentions that are biologically interrelated and must therefore be measured intact in small sample volumes. The application of this method to studies on the metabolism of butanoyl esters of morphine in whole brain homogenates is described.

Qualitative and quantitative analysis of petitgrain Eureka lemon essential oil by fused silica capillary column gas chromatography mass spectrometry

AbstractThe identification of Algerian petitgrain Eureka lemon essential oil was carried out by gas liquid chromatography‐mass spectrometry in electronic impact mode using a fused silica capillary column (FFAP). The results enabled a previous study on this oil to be completed where the relative retention data and chemical derivation reactions had been performed. A preparative gas chromatography was applied to give a better g.c.‐m.s.analysis of minor compounds; thus, two new products (citronellyl n‐propionate and cedrol) were revealed by this method. Only 80 compounds were identified after indexation of 137 mass spectra and after comparison with those in the literature because most mass spectra data banks are not well adapted for the identification of essential oils. A global comparison of the percentage composition of the major compounds of this oil with those in other petitgrain lemon essential oils has revealed distinct differences. From the mass spectra of nine monoterpenic hydrocarbons, it was shown that comparison of the intensity ratio of the characteristic fragment ions in EI mode, which has been suggested by some authors as a general method of identification of compounds with similar mass spectra, is not reliable.

Determination of Trace Amounts of Organic Pollutants in the Yellow River by Capillary Column Gas Chromatography-Mass Spectrometry

Abstract The trace organic pollutants in the Yellow River enriched by a solvent extraction method were pre-separated into four different fractions of fatty hydrocarbons, polycyclic aromatic hydrocarbons, polar compounds and organic acids and were analyzed by the use of combined capillary column gas chromatography-mass spectrometry. Using the combined techniques of relative retention value, mass spectra and mass chromatogram, more than 60 organic pollutants were identified, among which 16 fatty hydrocarbons and 6 polycyclic aromatic hydrocarbons which were quantitatively analyzed. The concentration range of fatty hydrocarbon was 5–800 ng/l, and that of polycyclic aromatic hydrocarbon was 0-90ng/l.

Urinary steroid profiles in pregnancy by capillary column gas chromatography

A qualitative and quantitative method for the estimation of urinary steroids during pregnancy by capillary column gas chromatography has been developed. Steroid conjugates were hydrolysed by enzymes and free steroids isolated by extraction using SEP-PAK C 18 cartridges. Methoxime-trimethylsilyl derivatives of the steroids were characterized by packed column gas chromatography-mass spectrometry and subsequently by their retention indices on capillary column gas chromatography. Of the 48 peaks resolved on the profiles about 35 were identified as steroids. The retention indices of reference steroids were very reproducible in the short term showing a mean coefficient of variation of 0.015%. The columns allowed 95% valley resolution of steroids whose retention indices differed by only 7 units. The use of an on-column injection technique contributed to the high precision for replicate injections (coefficient of variation < 1%) while for reference steroids, and well-resolved peaks in the urine profile, the mean coefficient of variation for the complete assay was less than 10%. To the best of our knowledge this is the first report concerning the quantitation, with good precision, of a large number of steroids in pregnancy urine.

Comparison of human hair by pyrolysis-capillary column gas chromatography and gas chromatography-mass spectrometry

Human head hairs from different donors were compared by pyrolysis-capillary column gas chromatography-mass spectrometry. A few major components in the pyrograms were found to differ among the donors. Some of these gave mass spectra similar to hexadodecanol, and others were identified as phenol and cresol. Other compounds identified in the hair pyrolyzates include carbon dioxide, carbon oxide sulfide, methanethiol, carbon disulfide, toluene, pyridine, styrene, pyrrole, methylpyrrole, and indole. The 3,6-substituted 2,5-piperazinediones, expected to result from cleavage of CN bonds in the polypeptide chains followed by cyclization, were not observed. The presence of a compound closely matching a reference spectrum for 5-methyl-2,4-imidazolidinedione suggested a mechanism leading to a family of 5-substituted 2,4-imidazolidinediones. Four of these compounds have been tentatively identified from their chemical ionization and electron impact ionization mass spectra. Each is thought to arise from the incorporation of a particular amino acid as follows: methyl-substituted from alanine, 1-methylethyl from valine, 1-methylpropyl from isoleucine, and 2-methylpropyl from leucine.

Comparison and identification of adhesives used in improvised explosive devices by pyrolysis-capillary column gas chromatography-mass spectrometry

Samples of 91 commercially available adhesives were analyzed by pyrolysis-capillary column gas chromatography-mass spectrometry (Py-GC 2-MS). Using the data system, a single, composite spectrum was generated representing over 1500 spectra from each pyrogram. The ions and relative ion abundances in the composite spectra reflect all of the components and their relative concentrations from each pyrogram. The 91 composite spectra were entered into an adhesives library on the data system. Five improvised explosive devices were constructed using 24 adhesives from the library collection. Following detonation, unconsumed bits of 13 different adhesives were recovered from the post-blast debris and identified by their association with specific fragments of the devices. When the composite spectra from the Py-GC 2-MS analysis of the recovered adhesives were searched against the library, the correct match was among the first 5 computer choices in all cases, and was the first choice in 7 of the 13 samples.

Capillary column gas chromatography—mass spectrometry of tabun

A simple of munitions grade tabun, known to contain several impurities, was studied by combined capillary column gas chromatography—mass spectrometry under both electron-impact and chemical ionization conditions. Five impurities, three of which were previously unreported in tabun, were identified and characterized based on their mass spectral data. Ammonia chemical ionization was particularly useful since this technique provided molecular ion information for allthe organophosphorous impurities.

Improved separation of the denopamine metabolites using capillary column gas chromatography-mass spectrometry.

Eight urinary metabolites of the positive inotropic agent denopamine, (-)-(R)-1-(p-hydroxyphenyl)-2-[(3, 4-dimethoxyphenethyl) amino] ethanol, in man were separated and identified by capillary column gas chromatography-mass spectrometry. The metabolites were products of oxidative 3'-or 4'-O-demethylation and/or meta-hydroxylation followed by meta-or para-catechol O-methyltransferase-methylation. Separation of the four isomers of 1-(hydroxymethoxyphenyl)-2-[(hydroxymethoxyphenethyl) amino] ethanol was made possible by the use of a capillary column.

Biosynthesis of 5,6-dihydroxyprostaglandin E 1, and F 1α from 5,6-dihydroxyeicosatrienoic acid by ram seminal vesicles

cis-5(6)Epoxy- cis-8,11,14-eicosatrienoic acid was recently found to be metabolized by ram seminal vesicles to 5-hydroxyprostaglandin I 1α and 5-hydroxyprostaglandin I 1β,5(6)epoxyprostaglandin E 1 and 5,6-dihydroxyprostaglandin E 1 The epoxide can be hydrolyzed by epoxide hydrolases to 5,6-dihydroxy-8,11,14-eicosatrienoic acid. The latter was incubated with microsomes of ram seminal vesicles for 2 min at 37°C and the polar metabolites were purified by reversed phase HPLC and analyzed by capillary column gas chromatography-mass spectrometry. The major metabolite was identified as 5,6-dihydroxyprostaglandin F 1α. In the presence of glutathione (1 mM), 5,6-dihydroxyprostaglandin E 1 was also formed. The 3H-labelled vicinal diol and the 3H-labelled epoxide were metabolized to polar products to a similar extent, but the formation of prostaglandin E compounds in the presence of glutathione was lower from the diol than from the epoxide or from arachidonic acid. The likely prostaglandin endoperoxide intermediates in the metabolism of the diol (5,6-dihydroxyprostaglandin G 1 and 5,6-dihydroxyprostaglandin H 1) thus appear to be less prone to be isomerized to prostaglandin E compounds than prostaglandins G 2 and H 2 and their 5(6)epoxy counterparts. 5(6)Epoxyprostaglandin E 1 and 5,6-dihydroxyprostaglandin E 1 can be chemically transformed into 5,6-dihydroxyprostaglandin B 1. The latter can be analyzed by HPLC or by mass fragmentography, and a simple chemical synthesis of 5,6-dihydroxyprostaglandin b 1 from prostaglandin E 2 is described.

Classification of bacteria by pyrolysis-capillary column gas chromatography-mass spectrometry and pattern recognition

Pyrolysis followed by capillary column gas chromatography-mass spectrometry has been applied to the classification of five bacterial species of the genus Flacobacterium. Data were subjected to computerized pattern recognition using the ARTHUR software package. The results indicate that classification potential is greatly improved by the use of mass fragmentography. Other factors such as growth media, harvesting and storage conditions were found to be relatively unimportant.

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.

Metabolism of 5(6)-expoxyeicosatrienoic acid by ram seminal vesicles: Formation of novel prostaglandin E 1 metabolites

5(6)-Epoxy-8,11,14-eicosatrienoic acid was incubated with microsomes or ram seminal vesicles in the presence of glutathione (1 mM) for 2 min at 37°C. Following extractive isolation on octadecasilane silica, the products were purified on straight-phase HPLC and separated into three major polar metabolites, which all showed maximal ultraviolet absorbance at 278 nm after treatment with alkali. The least-polar of the three metabolites was identified by capillary column gas chromatography-mass spectrometry as 5(6)-epoxyprostaglandin E 1 and the structure was confirmed by comparison with authentic material. The most-polar metabolite was identified as 5,6-dihydroxyprostaglandin E 1, while the metabolite of medium polarity was identified as its 85-lactone. When glutathione was omitted, 5-hydroxyprostaglandin I 1α and 5-hydroxyprostaglandin I 1β were previously identified as the two major metabolites. These results indicate that the postulated epoxyprostaglandin endoperoxide intermediates, 5(6)-epoxyprostaglandin G 1 and 5(6)-epoxyprostaglandin H 1, might be substrates for the endoperoxide E isomerase enzyme, since this enzyme requires glutathione as a cofactor.

Measurement of endogenous tryptamine in rat brain by capillary column gas chromatography mass spectrometry.

A capillary column gas chromatographic mass spectrometric method, involving the use of a deuterated analogue as internal standard, was developed and used to identify and quantify tryptamine in the rat brain. The mean level of tryptamine in rat whole brain was 0.54 pmol g-1.

Analysis of melatonin, 5-methoxytryptophol and 5-methoxyindoleacetic acid in the pineal gland and retina of hamster by capillary column gas chromatography—mass spectrometry

A specific capillary column gas chromatographic—mass spectrometric method was used to determine 5-methoxyindoles in the pineal gland and retina of the golden hamster during a light—dark (14:10) cycle. In the pineal gland, the mean levels of melatonin ranged from 0.15 to 2.4 pmol per gland, with a maximum in the dark. The levels of 5-methoxytryptophol and 5-methoxyindoleacetic acid were in the same range, but peaked during light. In the retina the levels of melatonin were about 100 pmol/g, and seemed not to differ between light and dark. The level of 5-methoxyindoleacetic acid were in the same range during light but were below the detection limit during dark.

Organophosphorus sulphides, sulphoxides and sulphones. Part I. Determination of residues in fruit and vegetables by gas-liquid chromatography.

Conditions have been established for the routine quantitative determination of residues of demephion, demeton-S-methyl, disulfoton, fenamiphos, fensulfothion, fenthion, phorate, terbufos, thiometon and their toxic metabolites following conversion into the sulphones. Packed column gas chromatography-mass spectrometry demonstrated that most of the sulphoxides tended to decompose under the conditions required for gas chromatography, whereas most of the sulphides and sulphones were unaffected by such conditions. Temephos and its metabolites and the metabolites of vamidothion decomposed completely during gas chromatography. Some suggestions are given for assessing and avoiding the column priming and enhancement problems often observed in the gas chromatography of these and other polar organophosphorus pesticides.