Determination of zeranol and beta-zearalanol in calf urine by immunoaffinity extraction and gas chromatography-mass spectrometry after repeated administration of zeranol

A method for the determination of zeranol and its metabolite beta-zearalanol in bovine urine is described. It has been applied to samples from calves given multiple subcutaneous doses of zeranol. Samples were extracted with immunoaffinity columns containing antibodies raised against zeranol and were analysed by gas chromatography-mass spectrometry. The immunoaffinity columns were prepared by coupling immunoglobulin G fractions obtained from rabbit antisera with a Sepharose matrix. The immunizing agent was carboxybutylzeranol coupled to bovine serum albumin. Gas chromatography-mass spectrometry was performed in the negative-ion chemical ionization mode, after derivatization of the compounds to their pentafluorobenzyl ethers, and allowed detection of analytes with a sensitivity of 0.01 ppb in spiked urine. The derivatization method and the gas chromatographic determination were also applied to the similar compounds zearalanone, zearalenone and beta-zearalenol. A synthesis of dideuterated zeranol and beta-zearalanol by isotopic exchange is described. These deuterated analogues had an isotopic purity of more than 99% and were used for quantitation of zeranol and beta-zearalanol by isotope dilution mass spectrometry. The recoveries of zeranol and beta-zearalanol, using the immunoaffinity columns, were determined after extraction from spiked urine and were 84 and 64%, respectively. The urines of treated calves were collected for several days after treatments and were analysed after hydrolysis with beta-glucuronidase and arylsulphatase. The samples showed variable but generally decreasing concentrations of zeranol and beta-zearalanol. The levels of beta-zearalanol ranged from less than 0.01 to 98 ppb and were 1.2-3.2 times higher than those of zeranol.     

气相色谱-质谱法分析硫芥子气及相关化合物

用气相色谱－质谱法对含硫芥子气类化合物进行了分析。探讨了长链芥子气的电子轰击电离的质谱规律，并对待测化合物的色谱保留数据进行了研究，在给定条件下，各种待测含硫芥子气在气相色谱柱中能有效的分离和鉴定。     

Studies on monoterpene glucosides and related natural products. XXXI. Gas chromatography and gas chromatography-mass spectrometry of iridoid and secoiridoid glucosides.

A total of 33 iridoid and secoiridoid glucosides were detected by gas chromatography on several columns such as OV-1 or OV-17. Representative glucosides were then subjected to gas chromatography-mass spectrometry, giving some characteristic peaks that permitted the discrimination of both types of glucosides from other compounds in most instances. The successful detection of both types of glucosides in several plant extracts showed the applicability of this combination of methods to small amounts of plant materials.     

Technology for the identification of unusual cis, cis octadecadienoic fatty acids.

In this article methods are presented for the separation and identification of unusual cis, cis dienoic and polygnoic long chain fatty acids. Special emphasis has been laid on the identification of cis, cis octadecadienoic acids. The steps followed are: after transesterification the fatty acid methyl esters are separated by preparative gas chromatography according to chain length followed by argentation chromatography on thin-layer plates. After hydroxylation of the double bonds with osmium tetroxide the polyhydroxy compounds are derivatized to the per-O-trimethylsilyl-ethers. Separation and identification of individual compounds are achieved by combined gas chromatography-mass spectrometry using SCOT columns and low ionization energy.     

Performances under representative pressure and temperature conditions of the gas chromatography-mass spectrometry space experiment to investigate Titan's atmospheric composition

In the frame of the calibration of the aerosol collector and pyrolyser, and gas chromatography-mass spectrometry experiments of the Huygens probe arrived at Titan, systematic experimental studies were led to estimate the influence of the operating conditions on the analyses that should have been achieved in the Titan's atmosphere. The primary objective of this study was to estimate the influence of operating conditions variations induced by (i) instrumental modifications made shortly before the probe launch which can have changed the operating pressures; (ii) the change of the probe environmental conditions (pressure, temperature) during its descent in the atmosphere; (iii) a possible deviation of pressure and temperature regulations from their nominal values because of the long journey of the instrument in space, or of other external events. The secondary objective of this work was to create an analytical database that can be used as a reference to treat the chromatograms obtained in situ, and help to identify chromatographically the analyzed species, complementary to mass spectrometry. Beyond the application to a specific instrument, this work was also useful to experimentally estimate the fundamental evolution of the separation as a function of the changes of operating conditions with time. The obtained results show (i) the significant influence of inlet and outlet pressure variation on the time of analysis, but not on the separation power. It thus enables to significantly shorten the analysis duration, and thus to analyze more compounds within the fixed time of analysis of the instrument; (ii) the significant influence of temperature on the retention. In this frame, the enthalpies of exchange between the gas phase and the stationary phase of the species were determined to be used to retrieve the analyzed species in case of deviation of the operating temperature; (iii) that the possible aging of the columns does not have influence on the columns efficiency and separation power; (iv) the analytical capabilities of the gas chromatography-mass spectrometry experiment within operating conditions representative of those encountered in situ. Finally, in spite of possible operating condition changes, it is shown that results coming from the gas chromatograph-mass spectrometer experiment, which are currently under analysis, could bring important information on the Titan's atmosphere and its history.     

Isotope dilution gas chromatography-mass spectrometry for the study of eicosanoid metabolism in human blood platelets

Stable isotope dilution gas chromatography-mass spectrometry provides one of the most important techniques for the quantitative measurement of eicosanoids. This technique was applied to the quantitation of hydroxyeicosatetraenoic acids, hydroxyheptadecatrienoic acid, thromboxane B2 and prostaglandin F2 alpha formed during platelet aggregation after stimulation of gel-filtered platelets with thrombin (0.25 U/ml) or collagen (2 micrograms/ml). Similar amounts of hydroxyheptadecatrienoic acid and thromboxane B2 were found after platelet activation. The ratio of formation of 12-hydroxyeicosatetraenoic acid to thromboxane B2 varied from donor to donor. Only small amounts of prostaglandin F2 alpha (up to 200 pg per 2.0.10(8) platelets) and basic values of 15-hydroxyeicosatetraenoic acid (up to 100 pg per 2.0.10(8) platelets) were measured using gas chromatography with negative ion chemical ionization mass spectrometry. In addition, different stable isotope dilutions were prepared and are discussed in detail.     

Determination of 4-aminobutyric acid, aspartate, glutamate and glutamine and their 13C stable-isotopic enrichment in brain tissue by gas chromatography-mass spectrometry

A selected-ion monitoring method was developed for measuring 4-aminobutyric acid, aspartate, glutamate, and glutamine in brain tissue. Natural isotopes of these amino acids and their stable-isotopic enrichment following intravenous infusion of a precursor, [13C]glucose, were quantitated. Frozen mouse brain tissue was homogenized in cold 80% ethanol, and the supernatant, equivalent to 1 mg of wet weight brain tissue, was extracted using solid-phase bonded silica ion-exchange columns. Aspartate and glutamate (dicarboxylic acids) were isolated from strong anion-exchange columns, whereas 4-aminobutyric acid and glutamine (neutral amino acids) were isolated from strong-cation exchange columns. n-Butyl ester pentafluoropropionyl amide derivatives of these amino acids were analyzed by gas chromatography-mass spectrometry using a methane positive chemical ionization mode after gas chromatographic separation on a wide-bore, fused-silica capillary column. The method is applicable to determination of brain concentrations of these amino acids as well as their fluxes following administration of a stable-isotopic tracer.     

Detection of trace levels of trichothecene mycotoxins in human urine by gas chromatography-mass spectrometry

A method is described for the simultaneous detection of the trichothecene mycotoxins T-2, HT-2, T-2 tetraol, diacetoxyscirpenol, 15-monoacetoxyscirpendiol, scirpentriol, nivalenol and deoxynivalenol, in human urine. Samples were extracted from Clin Elut columns and cleaned up using reversed-phase Sep-Pak C18 cartridges. Trichothecenes were derivatised as their heptafluorobutyryl esters, and detected by gas chromatography-mass spectrometry-selected-ion monitoring using electron impact ionisation. The method was validated by the analysis of 22 urine samples, spiked and submitted "blind" for analysis by another laboratory. An alternative gas chromatography-mass spectrometry method using negative ion chemical ionisation is also described and a preliminary comparison of the two methods made. The methods enabled levels down to 1 ppb to be detected, with confirmation of identity at levels between 2 and 5 ppb, depending on the toxin.     

Glass Capillary Columns In The Gas Chromatographic And Gas Chkomatocraphic-Mass Spectrometry Determination Of Trace Levels Of Kepone In Natural Waters

Abstract

The application of high-resolution glass capillary columns to the analysis for Kepone in environmental samples by gas chromatography and gas chromatography-mass spectrometry is described. Glass capillary columns make possible the rapid screening and analysis of Kepone at a lower detection limit of 2 ng/L in natural waters. However, even with the aid of glass capillary columns, electron capture determinations for Kepone are suDJect to error. The use of isopropanol in solutions containing Kepone was found to reduce the variability of the Kepone detector response by as much as six times. A discussion concerning the intricacies of Kepone analysis in natural waters is given.     

Analysis of drug metabolites by gas chromatography-mass spectrometry using glass capillary columns

Summary The routine use of glass-capillary columns in a general applications laboratory for gas chromatography-mass spectrometry is discussed. The instrumentation is described with emphasis on the interface between glass capillary columns and the mass spectrometer. Two examples of the analysis of metabolites demonstrate the successful use of this system.     

Detection of the illegal use of ethinylestradiol in cattle urine by gas chromatography-mass spectrometry

A method for the detection of ethinylestradiol in cattle urine is described, based on enzymic hydrolysis of the sample, clean-up by means of disposable octadecyl and amino solid-phase extraction columns, fractionation by reversed-phase high-performance liquid chromatography, and detection by gas chromatography-mass spectrometry (selected-ion monitoring). Identification is based on both gas chromatographic and mass spectrometric data. The method has been tested on urine samples for a collaborative study and all the results found were correct.     

Gas chromatographic-mass spectrometric analysis of some potential toxicants amongst volatile compounds emitted during large-scale thermal degradation of poly(acrylonitrile-butadiene-styrene) plastic

A number of compounds emitted during the thermal degradation of plastics are potentially toxic. This study was aimed at identifying the volatile compounds emitted during large-scale thermal degradation of poly(acrylonitrile-butadiene-styrene). About 5 g of the sample were degraded at between 25 and 470 degrees C in air and nitrogen in a device that can simulate temperature-programmed thermogravimetry. The volatiles were collected in dichloromethane using the solvent trap technique. Some of the 92 compounds identified by gas chromatography-mass spectrometry were found to have no hitherto documented toxicological profiles, even though they are potentially dangerous.     

Phenylalanine in whole blood and plasma--a candidate reference method

A method for the quantification of phenylalanine in whole blood and plasma by isotope dilution gas chromatography-mass spectrometry is presented. The use of an uncommon derivative allows a simple extraction procedure and the most basic mass spectrometer. The relative standard deviation was found to be 1.3% within-batch and 2.1% between-batch under optimum conditions, and the detection limit was found to be 7 pmol injected. The ruggedness of the procedure and sample handling conditions were also examined.     

鸽子粪挥发性成分的毛细管气相色谱分析

利用同时蒸馏萃取法（ＳＤＥ）提取了有治疗痔疮效果的鸽子粪中的挥发性成分。用毛细管ＧＣ／ＭＳ／ＤＳ联用法分离鉴定了４７种组分,占总峰面积的７１．５９％,再用保留指数和标样进一步确证了其中３９种化合物,占总峰面积的５７．１５％,其中含量较高的组分是十六碳酸（９．０３％）、乙酸乙酯（６．８５％）、乙醇（４．０３％）、１－乙氧基－２－甲基丙烷（３．８７％）。从化合物的种类看,主要为醇类（４个）、醛类（１１个）、酮类（４个）、酸类（８个）、酯类（５个）和酚类（２个）,它们共占总峰面积的４３．６８％。     

Determination of testosterone:epitestosterone ratio after pentafluorophenyldimethylsilyl-trimethylsilyl derivatisation using gas chromatography-mass spectrometry in equine urine

A highly specific method is described for measuring the testosterone:epitestosterone ratio in equine urine by gas chromatography-mass spectrometry (GC-MS) with stable isotope internal standards. The procedure was based on Serdolit Pad-1 resin extraction, enzymatic hydrolysis, and chemical derivatisation prior to instrumental analysis. The mixed derivatives, 3-trimethylsilyl-17-pentafluorophenyldimethylsilyl ether (3-TMS-17-flophemesyl) testosterone and epitestosterone, were found to have excellent analytical properties. The specificity of the derivatisation method exploits a unique feature of steroids: the selective exchange of the alcoholic flophemesyl ether for the trimethylsilyl ether. The sensitivity and specificity of the mixed 3-TMS-17-flophemesyl derivatives allow adequate determinations of testosterone and epitestosterone, even in urine from mares, in 5 ml samples. The repeatability of testosterone and epitestosterone was 6.2 and 5.7%, respectively, and their reproducibility was in the range of 6.4-8.7%.     

Authenticity assessment: a permanent challenge in food flavor and essential oil analysis

Both phenomena, enantioselectivity as well as isotope discrimination during biosynthesis, may serve as "endogenous" parameters, provided that suitable methods and comprehensive data from authentic sources are available. This review reports on enantioselective capillary gas chromatography and online methods of isotope-ratio mass spectrometry in the authentication of food flavor and essential oil compounds, referring to literature references published in the last decade.     

Application of polydivinylbenzene liquid chromatography columns to remove lipid material from fish tissue extracts for the analysis of semivolatile organics

Liquid chromatography columns of 100% polydivinylbenzene (DVB) (packing) were used to remove lipid material from fish extracts before analysis of several semivolatile organic pollutants by gas chromatography-mass spectrometry (GC-MS). This packing material was found to be durable as the columns could be operated to about 900 p.s.i. resulting in high efficiency separation. Recoveries and relative standard deviations for 18 polynuclear aromatic hydrocarbons fortified into a fish extract and cleaned up by multiple DVB columns in series were in the range of 86 to 123% and 4 to 11%, respectively.     

Detection by Gas Phase Analytical Methods of Derivatives of Barbiturate Epoxides

Abstract

Reactive epoxides, formed as intermediates in the enzymic hydroxylation of olefinic compounds, can be trapped by their reaction with trimethylchlorosilane and detected by gas chromatography and combined gas chromatography-mass spectrometry as the trimethylsilyl derivatives of their chlorohydrin adducts. Mass spectrometric identification of the products is facilitated by the characteristic isotope ratio of chlorine. By using these derivatives, epoxides have been detected as intermediates in the metabolic conversion in the rat of allylic barbiturates to their corresponding glycols.     

Comparison of the behavior of 13C- and deuterium-labeled polycyclic aromatic hydrocarbons in analyses by isotope dilution mass spectrometry in combination with pressurized liquid extraction

We examined the differences found in the concentrations of polycyclic aromatic hydrocarbons (PAHs) in sediment samples when determined by isotope dilution mass spectrometry (IDMS) using 13C-labeled PAHs (13C-PAHs) and deuterium-labeled PAHs (PAHs-d) as internal standards. The samples were analyzed by pressurized liquid extraction (PLE) in combination with gas chromatography-mass spectrometry. The observed concentrations with PAHs-d as internal standards were significantly (p<0.05) lower (1.9-4.3%) than those determined with 13C-PAHs. The most important factor responsible for the high recovery of PAHs-d relative to 13C-PAHs and native PAHs is the higher stability of PAHs-d during the PLE process.     

Gas chromatographic – mass spectrometric analysis of compounds generated upon thermal degradation of some stationary phases in gas chromatography – Part II

The applicability of capillary columns for gas chromatography is often limited by stationary phase degradation at elevated temperatures. In order to achieve a better understanding of column thermostability, column bleed products have been analyzed qualitatively by gas chromatography-mass spectrometry (GC-MS). Three silicone stationary phases were studied: SE-52, SE-54, and OV-1701. Each of these was immobilized in the columns. The proportion of cyclics containing diphenyl in column bleed from SE-52 reflected to a large extent the composition of the polymer, while for SE-54 the proportion of such cyclics was unexpectedly high. The polar moiety of OV-1701, the cyanopropyl(phenyl)siloxy unit, was found to exert a highly destabilizing effect on the polymer, and the thermal degradation products consisted mainly of cyclosiloxanes containing this unit.