Gas Chromatographic-mass Spectrometric Study Research Articles

Gas chromatographic–mass spectrometric analysis and subsequent quality improvement of plastic infusion packaging materials

Although the opalescence of sterile transparent plastic materials utilized for the packaging of parenteral infusion drugs is a serious quality problem, most suppliers do not report the exact compositions of such polymers, and no literature data are available. Similarly, no information is available as concerns the potential incompatibility of the inner bag and the overpouch. Our gas chromatographic–mass spectrometric study revealed that the cause of the opalescence is the presence of a low-molecular-weight slip additive, 13-docosenamide (erucamide), which is transferred into the primary infusion bag from the overpouch during the heat-sterilization process. Autoclaving trials confirmed the analytical results. In view of these findings, a new slip additive-free overpouch has been produced as secondary packaging material, which does not give rise to opalescence.

Analysis of Individual Oil Gland Secretion Profiles in Oribatid Mites (Acari: Oribatida)

Oil glands are paired opisthosomal sac-like glands that characterize the so-called “glandulate Oribatida” (Parhyposomata, Mixonomata, Desmonomata, Brachypylina, Astigmata). Among glandulate groups, a novel pool of characters for phylogenetic analyses was recently introduced by investigations into the chemistry of oil gland secretions. Secretion profiles appear to be species-specific, and moreover, reveal a clear evolutionary trend from early-derivative glandulate groups to late-derivative brachypylines. Due to limited secretion volumes, gas chromatographic-mass spectrometric studies thus far have mainly relied on pooled extracts from multiple individuals. Herein we present an extended approach to analyse individual profiles, using two model species. In Archegozetes longisetosus Aoki (Trhypochthoniidae), derived from a laboratory culture, oil gland secretions were homogenous among individuals and yielded ca. 325ng of secretion per individual. In strong contrast, between zero and 7000ng of secretion was extracted from individuals of Collohmannia gigantea Sellnick (Collohmanniidae) collected from nature, and several distinct sub-profiles were detected. Such detailed data regarding intraspecific variation of secretion profiles both within and among populations are expected to serve as novel tools to study poorly-known population relationships in Oribatida.

A Raman microscopic and gas chromatographic–mass spectrometric study of two 19th century overlapping Coptic icons of Anastasy Al-Romi

A Raman microscopic and gas chromatographic–mass spectrometric study of pigments and varnishes applied to two 19th century overlapping Coptic icons painted by Anastai Al-Romi in St. Mercurius Church, Egypt, has successfully identified the materials used. Optical microscopy was also used to determine the layered structured of the two icons. Ultraviolet imaging was used to study the underlying icon layers. The spectral analysis revealed that the pigments used in the upper icon layers comprise Prussian blue (Fe 4[Fe(CN 6] 3·14–16H 2O), orpiment (As 2S 3), chrome yellow (PbCrO 4·PbO), vermilion (HgS), lead white (2PbCO 3·Pb(OH) 2), gypsum (CaSO 4·2H 2O), chalk (CaCO 3) and lamp black (C). The presence of two organic pigments, Indian yellow (MgC 19H 16O 11·5H 2O) and kermes (C 16H 10O 8), is of interest. The pigments of the underlying icon are found to be Prussian blue, orpiment, chrome yellow, vermilion, lead white and gypsum. Pinaceae resin was applied as a protective varnish in both icons, as revealed by the total ion chromatograms obtained.

Gas chromatographic–mass spectrometric study of the degradation of phenolic compounds in wastewater olive oil by Azotobacter Chroococcum

Compounds present in wastewater olive oil (WWOO) which can be used in metabolic pathways of Azotobacter chroococcum ( A. chroococcum) have been investigated. Some compounds such as syringic acid, p-coumaric acid and syringaldehyde do not favour microorganism growing up. However, it has been shown that in batch culture, polyphenolic compounds (PCs) such as protocatetic acid and p-hydroxybenzoic acid do facilitate the growing up of microorganism. What is more, the maximum concentration in which bacteria can grow was 0.3% (w/v) for both polyphenols. At higher concentrations, substrate inhibition was observed; which is characterized by decreasing growth rates. Therefore, A. chroococcum can grow up using PCs as an individual source of carbon and energy supply but it is also dependent on the type of the compound and on its concentration. A gas chromatography coupled mass spectrometry method has been used for the study of the degradation of simple phenolic compounds.

Advanced Gas Chromatographic–Mass Spectrometric Studies for Identification of the Cellular Octadecenoate Isomers and Changes of Fatty Acid Composition Induced by Ethanol Stress in Escherichia coli and Escherichia coli O157:H7

Ethanol can be introduced to foods of various origins and is commonly used for surface disinfection. Low concentrations of residual ethanol may provide an opportunity for pathogens to adapt and grow. Change of cellular fatty acid composition is one of adaptation mechanisms enabling bacteria to grow under varied stresses. Since instrumental analyses of bacterial octadecenoate isomers are sophisticated, gas chromatographic analyses of the isomers, namely trans-9-octadecenoate, trans-11-octadecenoate, cis-9-octadecenoate, and cis-11-octadecenoate, and ethanol-induced formation of trans-9-octadecenoate in Escherichia coli and E. coli O157:H7 were intensively investigated. When an HP-1, a nonpolar capillary column, was used for gas chromatographic analyses of 28 authentic bacterial acid methyl esters, resolution was satisfied for all fatty acid components except trans-9-octadecenoate and cis-11-octadecenoate, being overlapped. When the column was replaced by an RTx-2330, a polar capillary column, all of the above-mentioned octadecenoate isomers were resolved. When cells of E. coli and E. coli O157:H7 were harvested after submerged cultivation (30°C, 150 rpm) in tryptic soy broth and tryptic soy broth supplemented with 5% ethanol at early stationary phase and subjected to cellular fatty acid analyses by using an HP-1 and RTx-2330 coupled with a mass detector, 12 fatty acids, i.e., trans-9-octadecenoate, 5 saturated fatty acids, 2 cyclopropane fatty acids and 4 cisunsaturated fatty acids, were identified. Individual fatty acid contents varied depending on nature of fatty acid, strain of E. coli, and supplement of ethanol. As affected by ethanol stress for both E. coli strains, contents of trans-9-octadecenoate increased, whereas contents of cyc-9,10-methylene octadecanoate (cyc-9,10-19:0) decreased significantly (P < 0.05). Apparently, both E. coli strains have rendered necessary fatty acid adaptation to survive and grow under ethanol stress.

Chemical constituents and antimicrobial and antioxidant potentials of essential oil and acetone extract of Nigella sativa seeds

AbstractThe antifungal, antibacterial and antioxidant potentials of essential oil and acetone extract of black cumin were investigated by different techniques. In the inverted petriplate method, the essential oil showed complete zones of inhibition against Penicillium citrinum at a 6 µl dose. Essential oil showed complete growth inhibition against Bacillus cereus, Bacillus subtilis and Staphylococcus aureus, Pseudomonas aeruginosa at 2000 and 3000 ppm, respectively, by the agar well diffusion method. The antioxidant activity was evaluated by measuring peroxide, TBA and total carbonyl values of rapeseed oil at fixed time intervals. Both the extract and essential oil showed strong antioxidant activity in comparison with butylated hydroxyanisole (BHA) and butylated hydroxytoluene (BHT). In addition, their inhibitory action in the linoleic acid system was studied by monitoring the accumulation of peroxide concentration. Their radical scavenging capacity was carried out on 2,2′‐diphenyl‐1‐picrylhydrazyl (DPPH) radical and they showed excellent scavenging activity in comparison with synthetic antioxidants. Their reducing power was also determined, demonstrating strong antioxidant capacity of both the essential oil and extract. Gas chromatographic and gas chromatographic–mass spectrometric studies on the essential oil resulted in the identification of 38 components representing 84.65% of the total amount. The major component was p‐cymene (36.2%) followed by thymoquinone (11.27%), α‐thujene (10.03%), longifolene (6.32%), β‐pinene (3.78%), α‐pinene (3.33%) and carvacrol (2.12%), whereas extract showed the presence of 16 components representing 97.9% of the total amount. The major components were linoleic acid (53.6%), thymoquinone (11.8%), palmitic acid (10%), p‐cymene (8.6%), longifolene (5.8%) and carvacrol (3.7%). Copyright © 2005 Society of Chemical Industry

Gas chromatographic–mass spectrometric study of the oil fractions produced by microwave-assisted pyrolysis of different sewage sludges

The pyrolysis of sewage sludge was studied in a microwave oven using graphite as microwave absorber. The pyrolysis temperature ranged from 800 to 1000 °C depending on the type of sewage sludge. A conventional electrical furnace was also employed in order to compare the results obtained with both methods. The pyrolysis oils were trapped in a series of condensers and their characteristics such as elemental analysis and calorific value were determined and compared with those of the initial sludge. The oil composition was analyzed by GC–MS. The oils from the microwave oven had n-alkanes and 1-alkenes, aromatic compounds, ranging from benzene derivatives to polycyclic aromatic hydrocarbons (PAHs), nitrogenated compounds, long chain aliphatic carboxylic acids, ketones and esters and also monoterpenes and steroids. The oil from the electric oven was composed basically of PAHs such as naphthalene, acenapthylene, phenanthrene, fluoranthene, benzo[ a]anthracene, benzofluoranthenes, benzopyrenes, indenepyrene, benzo[ ghi]perylene, and anthanthrene. In contrast, these compounds were not produced in the case of microwave-assisted pyrolysis.

The antispasmodic drug mebeverine leads to positive amphetamine results by fluorescence polarization immunoassay (FPIA)--studies on the toxicological analysis of urine by FPIA and GC-MS.

Mebeverine (Duspatal, MB), an antispasmodic drug, is the veratric acid ester of 4-[ethyl-[2-(4-methoxyphenyl)-1-methylethyl]amino]butan-1-ol (MB-OH), which is a N-substituted ethylamphetamine derivative. MB is metabolized via ester hydrolysis to MB alcohol (MB-OH) and veratric acid. N-Dehydroxybutylation leads to methoxyethylamphetamine (MO-EA) and, after O-demethylation, to hydroxy EA (HO-EA). N-Bisdealkylation leads to p-methoxyamphetamine (PMA). MO-EA and PMA are also known as designer drugs. Fluorescence polarization immunoassay (FPIA) and gas chromatographic-mass spectrometric studies on the toxicological analysis of MB after ingestion of a single 405-mg oral dose of MB were performed. We could show that intake of MB leads to positive FPIA results for amphetamine. The N-dehydroxybutyl metabolites of MB, MO-EA, HO-EA, and the bis-dealkyl metabolite PMA should be responsible for the positive immunoassay results. Using our systematic toxicological analysis procedure, every positive amphetamine immunoassay could be explained by detection of MO-EA, HO-EA, and/or PMA. Misinterpretation of the origin of MO-EA, HO-EA, or PMA can be avoided by detecting the specific (non-dehydroxybutylated) metabolites of MB, which are excreted for a much longer time after ingestion.

Gas chromatography–mass spectrometry of the stereoisomers of heterocyclic compounds. Part 3.† Perhydro-4-thia-s-indacene

A gas chromatographic–mass spectrometric study of mixtures of the stereoisomers of perhydro-4-thia-s-indacene (PHTI) has been carried out. Separation has been accomplished on a column packed with graphitized thermal carbon black (GTCB) and on a capillary column of high efficiency. In addition to the known cis-syn-cis isomer, five novel diastereomers have been found. The stereospecificity of their fragmentation under electron impact appeared to be quite distinct and mass spectra (70 eV) of cis-cis, trans-cis and trans-trans conjugated isomers were distinguished. An important part in the structural elucidation of the novel isomers is played by molecular statistical calculations of the thermodynamic parameters of their adsorption on GTCB, which were performed on the basis of hypothetical molecular structures of these compounds optimized by molecular mechanics. Evidence for the existence of cis-cis isomers with the middle ring in a boat conformation obtained from these data is discussed.

Gas chromatography–mass spectrometry of the stereoisomers of heterocyclic compounds. Part 2a.1 Perhydroxanthenes

The importance of GC-data for the structural elucidation of novel isomers by GC–MS is discussed. A gas chromatographic–mass spectrometric study of mixtures of the stereoisomers of perhydroxanthene (PHX) has been carried out. Separation has been accomplished on a column packed with graphitized thermal carbon black (GTCB) and on a capillary column of high efficiency. In accordance with the mass spectral evidence together with the known cis-syn-cis, trans-anti-cis and trans-syn-trans isomers four novel stereoisomers have been found. Three of them, cis-anti-cis, trans-syn-cis and trans-anti-trans are theoretically expected, whereas the fourth novel isomer is surprising and has been preliminarily assigned as conformer B of cis-syn-cis PHX. The stereospecificity of the fragmentation of PHX isomers under electron impact appears almost suppressed by the predominant formation of a stable oxonium ion [M – C3H7]+. The similarity of the mass spectra complicates the structural elucidation of novel isomers based on the qualitative relationships between their retention on the column packed with GTCB and hypothetical molecular structures.

Identification of polycyclic aromatic hydrocarbons in sugar cane soot by gas chromatography-mass spectrometry

Fly soot samples collected in the sugar cane fields after the process of burning were extracted in a Soxhlet apparatus (methylene chloride:methanol 4:1). The extracts were fractionated on silica gel Sep-Pak cartridges into three fractions. A gas chromatographic-mass spectrometric study of the fly soot extracts allowed the identification of the PAH with mutagenic and carcinogenic properties. Large amounts of aliphatic hydrocarbons, fatty acid esters and some PAHs were identified by GC-MS in full scan mode. GC-MS in the selective ion monitoring mode (SIM) was suitable for the determination of many PAHs, which are often present in the burnt biomass. 31 PAHs and 7 thiophens derivatives were identified. The presence of these compounds should be regarded as a caution to workers and the general population to avoid exposure to the fly soot.

Characterization of soluble organic matter from Youssoufia rock phosphate

Extractable lipids represent 12% of the total organic matter contained in Youssoufla rock phosphate. This soluble organic matter corresponds mainly to free, directly extractable lipids. They are dominantly neutral lipids (neutral/acid fraction ratio: 1.5). Gas chromatographic-mass spectrometric studies showed for the alkanes a bimodal distribution C 15C 21 and C 22C 33 dominated, respectively, by C 18 and C 27. The dominant hopanes were identified under the thermodynamically stable αβ-form, αββ-steranes were also present with the non-diagenetic ααα- and βαα-steranes. Phytane and pristane deriving from the transformation of chlorophyll chains were also identified. Acids were saturated linear C 12C 30 acids with a predominance of the C 16 and C 18 members, unsaturated C 16:1 and C 18:1 acids and even dicarboxylic acids. The results obtained suggest that the organic matter present in the phosphate has a marine origin with a significant continental contribution.

Gas chromatographic-mass spectrometric study of lipids and rapid diagnosis of Mycobacterium tuberculosis

The method suggested is based on the identification of tuberculostearic acid as a Mycobacterium tuberculosis marker. Bacterial culture and sputum of patients with pulmonary tuberculosis and lung disease of non-tuberculous etiology were investigated. A complete coincidence of the results of bacteriological and gas chromatographic-mass spectrometric (GC-MS) methods used in examining a group of patients with pulmonary tubercolosis was found. GC-MS ion monitoring provides a highly sensitive and rapid technique for the diagnosis of pulmonary tuberculosis.

Gas chromatographic—mass spectrometric study of reactions of halodeoxycelluloses with thiols in aqueous solutions

Chloro- and bromodeoxycelluloses with high degrees of substitution, prepared with halosuccinimide and triphenylphosphine under homogeneous conditions, were treated with eight thiols under moderately alkaline conditions. Bromodeoxycellulose was generally more reactive than chlorodeoxycellulose and carboxyl-bearing thiols such as mercaptoacetic acid were less reactive than neutral thiols such as benzenethiol. The maximum conversion of halodeoxyglucose units to thio derivatives was 65%. When the reaction was run at high alkalinity at 60 °C, elimination of hydrogen halide to yield 3,6-anhydroglucose and/or 5,6-glucosene units took place appreciably as a side reaction. Hydrolysates of the reaction products with thiols having no carboxyl group were analyzed by gas chromatography-mass spectrometry as trifluoroacetates and the formation of S-substituted 6-thio-6-deoxyglucose units was confirmed.

Triterpane distributions in diapir-related asphalts

A gas chromatographic-mass spectrometric study of solvent-soluble extracts from asphalt-rich sediments in a diapir-intruded crude oil reservoir rock has demonstrated the extended biodegradation of the hydrocarbons in the strata in contact with the diapir. The process has led to a sedimentary hydrocarbon composition dominated by unresolved complex mixtures of aliphatic and aromatic hydrocarbons in which two main groups of resolved peaks in the gas chromatograms can be recognized. The dominant group encompasses the compounds preserved in these conditions and is composed of two distributions of hexacyclic hopanoids, a series of C 32-C 35 20,32-cyclobishomohopanes and a new series of C 33-C 35 homologues whose structure is not yet fully elucidated. The second group corresponds to partly transformed aliphatic and aromatic structures, namely series of C 27-C 30 8,14-seco-hopanes and C 27-C 31 D-ring aromatic 8,14-secohopanes.

Gas chromatographic-mass spectrometric study of the reductive silylation of hydroxyquinones

Reductive trimethylsilylation was carried out with N-methyl-N-trimethylsilyltrifluoroacetamide under optimized conditions to afford quantitatively the all-silylated products of several hydroxynaphthoquinones and -anthraquinones. The silylated products were investigated by GC-MS. The fragmentation patterns of the compounds provided valuable information about their structure and consequently about the structure of the initial hydroxyquinones. The silylation and GC-MS separation scheme was applied to mixtures of hydroxyquinones, leading to effective separation of all the ingredients, which included several hydroxyquinone isomers.

Determination of the fatty acids and oil content of evening primrose ( Oenothera biennis L.)

A rapid method for the analyses of oil content and individual fatty acids of evening primrose ( Oenothera biennis L.) is described. Oil was extracted from the seed with a Polytron probe generator using petroleum ether. A portion of the extract was concentrated to determine oil content. Results obtained with the Polytron extraction procedure were comparable to those obtained with a Soxhlet extraction procedure using the same solvent. Saponification of the oil with methanolic sodium hydroxide, methylation with methanolic sulfuric acid, and extraction of the esters with hexane was accomplished in a single reaction vial. Quantitation of the extracted esters was carried out by capillary gas chromatography. A number of fatty acids were identified by gas chromatographic-mass spectrometric studies of the extracted esters and methyl esters separated by their degree of unsaturation with silver nitrate-silicic acid chromatography. Saturated fatty acids from C 12 to C 24 were present in the oil with the even numbered acids present in the larger amounts. Eight monounsaturated fatty acids from C 14:1 to C 20:1 were identified with C 18:1 (n-9) as the major constituent of this fraction. Seven polyunsaturated fatty acids were identified with C 18:2 (n-6) and C 18:3 (n-6) as the major component. Analysis of seeds from different parts of evening primrose plants showed that differences in gamma-linolenic [C 18:3 (n-6)] acid and oil content exist due to location of the seed pods.

Gas chromatographic-mass spectrometric characterization of polycyclic aromatic hydrocarbon mixtures in polluted coastal sediments

A gas chromatographic-mass spectrometric (C-MS) study of polycyclic aromatic hydrocarbon (PAH) composition of a series of 72 marine sediments collected from the Guipuzcoan Coast (Bay of Biscay, Spain) showed three end-member distributions, one related to pyrolytic soot contributions (type A), another to combined paper mill effluents and soot inputs (type B) and the third to petrogenic residues (type C). The detailed composition of each of these end-member mixtures is given. Further examination of the PAH extracts by GC-negative ion chemical ionization MS illutrated several previously unreported selectivity effects such as enhancement of the parent PAHs eluting with longer retention times and the increased response factor of the alkyl homologues corresponding to the m/z 252,276 and 302 hydrocarbons.

Gas chromatographic screening of organic compounds in urban aerosols: Selectivity effects in semi-polar columns

A gas chromatographic-mass spectrometric study of aerosols collected in Barcelona allowed the identification of the major sources of airborne organic matter in an urban environment. The extracts were separated by column chromatography into three fractions encompassing aliphatic hydrocarbons, aromatic hydrocarbons plus semi-polar compounds and polar products. The overall procedure allowed the identification of 108 molecular species that were grouped according to their precursors. The study also allowed the characterization of significant changes in the elution order of linear and polycyclic molecules of similar retention using different semi-polar capillary columns such as DB-5, SE-52, CP-Sil 8 CB, SE-54 and HP-5.

Antigenic changes of the glomerular basement membrane after incorporation of hydroxyproline isomers.

We investigated antigenic changes of murine glomerular basement membrane (GBM) collagen type IV after oral feedings of 3-cis- or 4-cis-hydroxyproline. As shown by thin layer chromatography and gas chromatographic-mass spectrometric studies, 3-cis- and 4-cis-hydroxyproline were incorporated into the GBM collagen instead of the normal trans isomer and led to a considerable reduction of the collagen antibody reactivity on indirect immunofluorescence, passive hemagglutination and radioimmunoassay when compared to GBM collagen of control animals. We speculate that antigen modification due to the incorporation of stereoisomers could serve as a model for basement membrane immunopathology.