Combined Capillary Gas Chromatography Research Articles

Establishing the Association between Blood Levels of Chloroform in Children and Concentrations of Chloroform and Its Derivatives in Drinking Water of Centralized Water Supply Systems

Background: Surface reservoirs remain one of the priority sources of drinking water in the Russian Federation whereas the increasing anthropogenic effect on the environment does not exclude the possibility of contamination of surface waters with toxic compounds. The use of traditional methods of water disinfection with active chlorine aggravates the situation and leads to formation of highly toxic organochlorine compounds. In this regard, one of the urgent hygienic problems is to establish health effect of these toxicants in the population including its most sensitive groups. The objective of the study was to establish and quantify the relationship between concentrations of chloroform and its derivatives in drinking water and blood levels of organochlorine compounds in children consuming potable water with a higher content of chlorine and its derivatives. Materials and methods: The study was conducted on six territories of the Perm Region constituting an observation area where drinking water was noncompliant with hygienic standards by a number of indices, and a comparison area. The analysis of trihalomethanes in drinking water samples was carried out in accordance with the requirements of sanitary regulations SanPiN 2.1.4.1074–01. The levels of trihalomethanes (chloroform, carbon tetrachloride, dibromochloromethane, dichlorobromethane, and 1,2-dichloroethane) in children’s blood samples were analyzed by capillary gas chromatography in combination with a specific detector to increase selectivity and sensitivity of determination. We used a Kristall-5000 gas chromatograph with an Optima-5 capillary column (25 m × 0.32 mm × 0.5 μL) and a selective electron capture detector (ECD). Results: The data of comprehensive chemical analyses of average levels of trihalomethanes in blood samples of children consuming drinking water with an increased content of determined compounds (up to 3.5 MPC) and the water complying with hygienic standards are presented. We observed significant differences (р<0.005) between two groups in the blood levels of chloroform, carbon tetrachloride, and 1,2-dichloroethane that were 5.6, 6 and 24 times higher in children of the test group compared to the controls. Conclusion: We revealed a statistically significant causal relationship between the increase in chloroform concentrations in drinking water and the increase in blood levels of chloroform in children described by the equation у=0.00188+0.01782х (R2=0.263, p=0.0018).

Methanethiol, an Off-Flavor Produced from the Thermal Treatment of Mandarin Juices: A Study of Citrus Sulfur Volatiles.

The off-flavor produced after thermal stabilization of mandarin (Citrus reticulata, Blanco) juices has limited the production of commercial juices. Methanethiol, a putrid-smelling sulfur volatile, has been identified for the first time in heated mandarin juices. Identification was achieved using a combination of capillary gas chromatography with two dissimilar columns and a dual sulfur-specific pulsed flame photometric detector and selected ion mass spectrometry detection. Static headspace solid-phase microextraction quantitation found that average odor activity values (OAVs) in heated juices were 25.5 for methanethiol compared to 10.8 for dimethyl sulfide. OAVs for methanethiol and dimethyl sulfide in fresh juices were ND (not detected) and 5.5, respectively. Hydrogen sulfide, carbonyl sulfide, carbon disulfide, and dimethyl disulfide were also identified and quantitated. Thermal decomposition studies of nonvolatile sulfur-containing potential precursors indicated that methionine was the major source of methanethiol. Additional heating studies with model juices demonstrated that ascorbic acid greatly accelerated the formation of methanethiol and methional, as well as dimethyl di and tri sulfides.

Evidence of Reduced Agmatine Concentrations in the Cerebral Cortex of Suicides.

BackgroundThe polyamines are a group of ubiquitous low-molecular–weight aliphatic molecules that play an essential role in various physiological functions of the mammalian CNS. Previous literature has indicated alterations in the expression of polyamine-related genes in the brains of individuals who died by suicide, including downregulation of spermidine/spermine N1-acetyltransferase, a key enzyme involved in polyamine catabolism. One such polyamine, agmatine, has been shown to act as an antidepressant in animal models of depressive-like behavior. However, agmatine concentrations have not been explored in postmortem human brain of individuals who died by suicide.MethodsTo measure agmatine in postmortem human brain tissue, we employed our previously published high-resolution capillary gas chromatography in combination with mass spectrometry method. Using this method, we analyzed agmatine levels in a total of 120 tissue samples from Brodmann areas 4, 11, and 44 of 40 male subjects comprising controls (n=13), individuals who died by suicide and met criteria for major depressive disorder (n=14), and subjects who died by suicide and did not meet criteria for major depressive disorder (n=13).ResultsAgmatine fell within the expected nanomolar range and was significantly reduced in the cortex of suicides, irrespective of meeting criteria for major depressive disorder compared with controls.ConclusionsThis is the first gas chromatography-mass spectrometry study to analyze agmatine concentrations in human postmortem brain of individuals who died by suicide. These results add to our mechanistic understanding of the role that the polyamine stress response pathway may play in the neurobiology of major depression and/or suicide.

Spectrophotometric Determination of Chloroquine in the Hair of Mice

Background: Hair analysis for illicit, recreational and therapeutic drugs though an evolving science is easier, less invasive of privacy and there is less chance of tampering with the sample to affect results. Often, a combination of capillary gas chromatography with mass spectrometry, though with known short comings, is preferred for detection of drugs in hair specimen. Objectives: This study aimed at determination of chloroquine in the hair of mice by Ultra-Violet spectrophotometry. It has the advantage of being easy to operate and sensitive to trace amount. Methods: Twenty-five mice weighing about 25g each were administered chloroquine phosphate intramuscularly once a week for 4 weeks. Hair was harvested from the same spot before, during administration and at the end of dosing. The samples of hair were extracted with methanol and the resultant residue dissolved in 0.1M HCl. The resulting solutions were then run with the Ultra-Violet spectrophotometer to determine their concentrations using the calibration curve of the reference material. Results: There was proportionate significant increase in the concentration of chloroquine phosphate in hair at the intervals of administration. The amount of chloroquine detected in hair samples increased from 2.98x 10- 3/10g of hair on the second week of administration to 4.88x10-3/10g of hair on the fourth week of administration. Conclusion: The result from the present study showed that although a new innovation, hair testing using Ultra-Violet spectrophotometry is a valuable has been seen as a valuable tool for drug analysis.

Chemical composition and antibacterial activity of Teucrium polium essential oil against urinary isolates of Klebsiella pneumoniae

The alarming resistance of many bacterial pathogens to most available antibiotics has increased interest in natural plant products as alternative antibacterial agents. In this research, the antibacterial activity of Teucrium polium essential oil was determined against urinary isolates of Klebsiella pneumoniae. The aerial parts of T. polium were collected at full flowering stage in Tehran, Iran. The essential oil was isolated by hydrodistillation and analyzed by a combination of capillary gas chromatography (GC) and gas chromatography–mass spectometry (GC–MS) Antibacterial activity was measured against fifteen clinical isolates of K. pneumoniae by disc diffusion. Minimum inhibitory and bactericidal concentrations were also determined using broth microdilution. Twenty constituents were detected in T. polium essential oil of which the major components were β-caryophyllene (29%), farnesene (13%), β-pinene (11%) followed by germacrene D (6.5%) and α-pinene (5.5%). All K. pneumoniae clinical test isolates were susceptible to the essential oil by disc diffusion with inhibition zones within the range of 14–28.5 mm. Minimum inhibitory and bactericidal concentration values were 0.62–1.25 mg/ml and confirmed the disc test results. T. polium essential oil may have a potential for use against multidrug resistant organisms such as clinical isolates of K. pneumoniae.

Simulation Experiments and Kinetics for the Formation of Organic Sulfide in Marine Carbonate Reservoirs

Thermal simulation experiments on the system of gasoline and magnesium sulfate were carried out using an autoclave operating at high temperature and high pressure in the presence of water. Properties of the gas-oil-solid 3-phase products were analyzed by some advanced analytical methods including gas chromatography, microcoulometry, capillary gas chromatography in combination with a pulsed flame photometric detector, FT-IR and X-ray diffraction. The results showed that the reaction could proceed at 450℃ - 550℃ to produce MgO, S, C, H2S, CO2 and a series of organic sulfides such as mercaptans, sulfoethers and thiophenes as the main products. According to the reaction kinetics, the calculated activation energy of the reaction is 68.9 kJ·mol-1.

Determination of odorous sulfur compounds in air by Tenax GR preconcentration and capillary gas chromatography in combination with flameless sulfur chemiluminescence detection

A liner of PTV injector packed with the solid adsorbent Tenax GR was used to enrich ambient levels of volatile sulfur compounds, then the sulfur gases were thermally released according to programmed temperature from Tenax GR trap and re‐collected in a column cooled with liquid nitrogen. The sulfur compounds were revolatilized and directly transferred to the system of capillary‐column gas chromatography/flameless sulfur chemiluminescence detector for analysis. The PTV injector has been used as a thermal desorption chamber for determination of sulfur compounds. The sulfur gaseous compounds known to cause nuisance odors in the air from sewerage treatment tanks of a chemical petroleum company and hoggery are determined.

Trans fatty acids in adipose tissue of French women in relation to their dietary sources.

This study reports the fatty acid composition of subcutaneous adipose tissue in French women with special emphasis on the content of trans fatty acids originating from two main dietary sources, ruminant fats and partially hydrogenated vegetable oils (PHVO). Adipose tissue trans fatty acid levels from 71 women, recruited between 1997 and 1998, were determined using a combination of capillary gas chromatography and silver nitrate thin-layer chromatography. Results indicate that on average cis monounsaturates accounted for 47.9% of total fatty acids, saturates for 32.2%, and linoleic acid for 14.4%. Cis n-3 polyunsaturates represented only 0.7%. Total content of trans fatty acids was 2.32 +/- 0.50%, consisting of trans 18:1 (1.97 +/- 0.49%), trans 18:2 (0.28 +/- 0.08%), and trans 16:1 (0.06 +/- 0.03%). Trans 18:3 isomers were not detectable. The level of trans fatty acids found in adipose tissue of French women was lower than those reported for Canada, the United States, and Northern European countries but higher than that determined in Spain. Therefore, trans fatty acid consumption in France appears to be intermediate between that of the United States or North Europe and that of Spain. Based on the equation of Enig et al., we estimated the mean daily trans 18:1 acid intake of French women at 1.9 g per person. The major trans 18:1 isomer in adipose tissue was delta11 trans, as in ruminant fats. Estimates of relative contribution of trans fatty acid intake were 55% from ruminant fats and 45% from PHVO. This pattern contrasts sharply with those established for Canada and the United States where PHVO is reported to be the major dietary source of trans fatty acids.

A New Cell for Single Sided Headspace Sampling and Evaluation of Barrier Function in Laminated Paperboard

A new cell for single sided headspace sampling has been developed for the analysis of volatile organic compounds from food packaging paperboard and laminated paperboard. The cell, which samples the volatile organic compounds over a selected surface, is useful for determining the barrier function of laminated paperboards with respect to volatile compounds. The analysis of volatile organic compounds is carried out by purge and trap capillary gas chromatography in combination with mass spectrometric detection and compound identification. The new sampling cell was constructed to facilitate specific analysis of organic compounds from only one side of a laminated paperboard. The construction and the operating principles of the new sampling device are described. The repeatability of the single sided headspace procedure was found to be quite good. Relative standard deviations of about 5–7% were obtained for the major compounds quantified in replicate headspace analyses of a laminated paperboard. The volatile compounds released from the inner side of a food packaging paperboard sample with different surface composition on the two sides were determined. The barrier function against volatile organic compounds of some laminated paperboards was investigated employing the new headspace cell.

Urinary Volatile Profiles of the Deermouse (Peromyscus maniculatus) Pertaining to Gender and Age

Biological aspects of chemical communication in the deermouse have been extensively documented in the past. To provide a broad characterization of the urinary volatile compounds (potential chemosignals), the urine samples from adult and young animals of both sexes, as well as from castrated animals, were examined. The volatiles were extracted through a dynamic headspace technique and analyzed by combined capillary gas chromatography–mass spectrometry. The major constituents have been identified as various ketones, aldehydes, pyrazines, pyridines, quinolines, a thiazole, an amide, and a nitrile. While no chromatographic peaks were found to be unique to gender or age, quantitative analyses revealed that numerous compounds exhibited significant variations among the different groups. Their endocrine dependencies suggest a potential chemosignaling function.

Chemical Constituents from Shoots of Hordeum vulgare Infested by the Aphid Schizaphis graminum

Stress, pathogens or insects induce profound changes in the expression of the chemical constituents of plants. Some of these changes could be adaptations to the new conditions or the expression of new defensive characteristics. The purpose of this paper was to analyze the effect of aphid infestation on the composition of endogenous compound, in barley leaves. Leaf waxes were obtained by washing with dichloromethane and remaining compounds were extracted with ethyl acetate and ethanol from homogenized leaves. The identification of compounds was done by combined capillary gas chromatography and mass spectrometry. Epicuticular compounds detected in barley after 6 days of aphid infestation were as follows (%): (1) 1-docosene (1.98), (2) 1-octadecene (2.07), (3) phytol (0.81). Epicuticular compounds in non-infested plants were (4) isophytol (0.83), (5) N-cyclohexyl-cyclohexanamine, (0.11) (6) 5-pentadecyl-1,3-benzenediol (2.10). In ethyl acetate extracts from infested plants the main compounds were: (1) (2.02), (7) 2,5-diethylpyrazine (0.61), (8) (5E)-eicosene (1.61), (9) (3E)-eicosene (1.93), (10) (9E)-eicosene (1.80). In non-infested plants the only detected compounds were (1) (1.02), (6) (1.91), and (7) (0.43). In methanol extracts from infested plants the following compounds were identified: (6) (2.15), (7) (0.21), (11) 2,2,6.6 tetramethyl- piperidine (0.12), (12) indole (1.01), (13) heptadecane (0.10), (14) methyl-β-ᴅ-glucopyranoside (0.21), (15) 2,5- dihydroxybenzaldehyde (0.27) and (16) N-phenyl-2-naphthalenamine (0.29). In polar extracts from non-infested plants the most abundant compounds were (4) (1.40), (7) (0.18), (17) (9Z,12Z,15Z)-octadecatrienoic methyl ester (1.01), (18) (9Z,15Z)- octadienoic methyl ester (2.01), and (19) hexadecanoic methyl ester (1.93). Compounds 4, 5 and 7 -1 9 are described for the first time in Hordeum vulgare.

Chemical Composition of Essential Oils from Three Southern Brazilian Species of Mikania (Asteraceae)

Samples of essential oils from leaves of Mikania hirsutissima DC, M. involucrata Hook, et Am. and M. laevigata Shultz Bip. ex Baker were analyzed by a combination of capillary gas chromatography and GC/MS. Forty one components have been identified representing 70–95% of the oils content. The oils of M. involucrata and M. laevigata are quite similar and constituted by sesquiterpenes, represented mainly by β-caryophyllene (18.9% and 20.9%), germacrene D (9.9% and 29.8%) and bicyclogermacrene (28.1% and 13.4%). The oil of M. hirsutissima is also characterized by sesquiterpenes, and the major components are ar-curcumene (15.0%) and spathulenol (10.2%), and a small fraction (6.5%) of aliphatic compounds.

Specific migration of di‐(2‐ethylhexyl)adipate (DEHA) from plasticized PVC film: Results from an enforcement campaign

A control campaign on the correct labelling of plasticized PVC film according to current legislation on food contact materials has been performed. Analytical methods based on the isotope dilution technique were developed. For enforcement purposes, the films were exposed to the official food simulant, olive oil, followed by clean‐up using size exclusion chromatography and final determination of di‐(2‐ethylhexyl)adipate (DEHA) by combined capillary gas chromatography and mass spectrometry (GC‐MS). In the initial screening, the samples were exposed to the alternative food simulant, isooctane, and DEHA could be determined by GC—MS without further clean‐up. A good consistency between results from the two different methods was obtained. During the campaign, 49 samples of PVC films, the majority intended for use in retail shops, were sampled from importers and wholesalers by the Municipal Food Control Units. Initially, all films were screened for the migration into isooctane (exposed 2 h at 40° C) of DEHA and other potentially present low molecular weight plasticizers using full scanning mass spectrometry. Films showing a substantial migration of DEHA were further tested with olive oil according to the declared field of application (exposed for 10 days at 40° C). In 47 of the 49 films the migrate contained a substantial amount of DEHA. In 46 films the migration exceeded the specific migration limit of 3 mg/dm2 after use of the relevant reduction factor given in legislation. However, because of the general uncertainty of the analytical method and because the variation in the thickness of the films was calculated to be 1 mg/dm2, the action limit in this campaign was 4 mg/cm2. A migration higher than this action limit was found in 42 films (89% of the samples) and these films were deemed to be illegal according to their present declared field of application as given by their labelling. In a few cases, some migration of the plasticizer di‐n‐butyl phthalate was seen.

Biological monitoring of pyrethroid metabolites in urine of pest control operators

Due to their low mammalian toxicity but high insectical activity, pyrethroids are increasingly used for pest control. The objective of the present study was the development of a biological monitoring program to determine exposure to pyrethroids. A diastereoselective detection of the major pyrethroid metabolites cis- and trans-3-(2,2-dichlorovinyl)-2,2-dirnethlcyclopropanecarboxylic acid, cis-3-(2,2-dibromovinyl)-2,2-dimethylcyclopropanecarboxylic acid, 3-phenoxybenzoic acid and fluorophenoxybenzoic acid by capillary gas chromatography in combination with mass selective detection was applied. The limits of determination ranged between 0.5 and 1 μg/1 urine, depending on the metabolite concerned. It was demonstrated that pyrethroid metabolites were detectable in urine for a period of elimination up to 3.5 days after exposure to cyfluthrin. Fluorophenoxybenzoic acid was shown to be a suitable biomarker for exposure to cyfluthrin. The presented method was adequate for monitoring pyrethroids in occupationally exposed subjects.

Chemical Composition of the Leaf Oil ofPectis prostrataCav. from Cuba

ABSTRACT The leaf oil of Pectis prostrata Cav. of Cuban origin has been analyzed by a combination of capillary gas chromatography and GC/MS. The oil contained more than 40 constituents of which 24 have been identified. The main constituents found were limonene (16.20%) and perillaldehyde (70.74%).

Chemical Composition of the Leaf Oil ofPimenta dioicaL. from Cuba

ABSTRACT The leaf oil of Pimenta dioica L. of Cuban origin has been analyzed by a combination of capillary gas chromatography and GC/MS. The oil contained more than fifty components, of which more than forty have been identified. The main constituent found was eugenol (54.26%).

The fatty acid composition of the seeds ofGinkgo biloba

AbstractThe fatty acid composition of seeds ofGinkgo biloba has been examined by a combination of capillary gas chromatography, silver ion high‐performance liquid chromatography and gas chromatography/mass spectrometry. Some of the fatty acids identified are unusual in plants and were rather different from those reported earlier. These include ananteiso‐methyl branched fatty acid, 14‐methylhexadecanoic acid, 5,9‐octadecadienoic acid, and 5,9,12‐octadecatrienoic acid. Fourier‐transform infrared spectroscopy confirmed that all of the double bonds were of thecis‐configuration.

High‐speed narrow‐bore capillary gas chromatography in combination with a fast double‐focusing mass spectrometer

AbstractIn this work the application of high‐speed narrow‐bore capillary GC in combination with a fast scanning double focusing magnetic sector mass spectrometer is evaluated. Special emphasis is placed upon detection limits and scan speed in the full scan mode and in the selected ion monitoring mode (SIM). In the full scan mode, up to 20 scans per second could be obtained. The detection limits are in the low picogram range in the full scan mode and improve even to 5 to 50 fg in the SIM mode, depending on the sample complexity and mass resolving power. It will be illustrated that by increasing the resolution in the SIM mode, interferences from ions of the same nominal mass‐to‐charge ratio as the ions of interest are significantly reduced. Chemical background noise can therefore be largely eliminated, thus enhancing the signal‐to‐noise ratio.

Gas Chromatography-Isotope Ratio Mass Spectrometry in the Analysis of Peppermint Oil and Its Importance in the Authenticity Control

ABSTRACT Capillary gas chromatography coupled on-line with isotope ratio mass spectrometry (GC/IRMS) is used to determine the δ13CPDB-values of some typical peppermint oil constituents. By the method of the internal isotopic standard (i-IST), a characteristic isotopic fingerprint of authentic peppermint oil is established and used for the authenticity control of commercially available peppermint oils. Furthermore, enantioselective capillary gas chromatography in combination with IRMS (enantio-GC/IRMS) is used to prove the genuineness of peppermint oil.

Oriental Lacquer III. Composition of the Urushiol Fraction of the Sap of Rhus verniciflua

The urushi fraction of several samples of the sap of Rhus verniciflua was analyzed by a combination of capillary gas chromatography, supercritical fluid chromatography, high resolution NMR spectroscopy and two techniques of mass spectrometry. The composition of the urushi fraction of these samples was found to consist in general of the components that had been found by former analyses of urushi samples. Some new understanding of the components recognized gives a more accurate recognition of the ingredients of oriental lacquers.