Use Of Gas-liquid Chromatography Research Articles

1.6-Hexanediol based deep eutectic solvent and their excess data at infinite dilution

For over two decades, deep eutectic solvents have offered pre-eminence characteristics with the purpose of improving the issues of both ionic liquids and traditional solvents. The affordability, ease of preparation, in-flammability, non-or low toxicity, biodegradability, and other environmental advantages of DESs make them more appealing as green solvents. In the present study, 1-ethyl-1-methylpyrrolidinium bromide, a hydrogen bond accepter (HBA), was paired with 1,6-hexanediol (1,6-HDO), a hydrogen bond donor (HBD), to produce a DES with a mole ratio of 1:2. With the use of gas liquid chromatography (GLC), the infinite dilution activity coefficients (IDACs) of 32 different solutes were measured at different temperatures (313.15–343.15) K and atmospheric pressures. The partial molar properties, i.e., enthalpy, entropy, and Gibbs free energy, were calculated from the IDAC values at a reference temperature of T = 313.15 K to give more details for molecular interaction interpretation. Lastly, the selectivity and capacity values of separation problems such as benzene/acetone, benzene/cyclohexane, and cyclohexane/acetone were calculated from the IDAC values. The investigated DES was discovered to have good performance and could be used in industrial processes such as petroleum distillation, separation, extraction, and so on.

Composition of fatty acids in the maternal and umbilical cord plasma of adolescent and adult mothers: relationship with anthropometric parameters of newborn

BackgroundConsidering the importance of long chain polyunsaturated fatty acids to fetal development and the lack of studies that have compared the status of fatty acids between adolescents and adults mothers, the purpose of this study was to evaluate the composition of fatty acids in maternal and umbilical cord plasma from adolescent and adults mothers.MethodsForty pregnant adolescents and forty pregnant adults were selected to assess the distribution profile of fatty acids in the maternal and umbilical cord plasma. Quantification of fatty acids in the total lipids of the sample groups was performed through the use of gas-liquid chromatography.ResultsThe maternal and umbilical cord plasma of the adolescents showed a greater concentration of AA than did that of the adults (P < 0.05). However, a greater percentage of EPA was found in the umbilical cord plasma of the adults (P < 0.05). DHA in the plasma of the adolescent mothers correlated positively to birth weight and head circumference.ConclusionsThis suggests that in situations of greater nutritional risk, as in adolescent pregnancy, n-3PUFA concentrations have a greater influence on the proper development of newborns. Moreover, variations in fatty acid concentrations in the maternal and cord plasma of adolescents and adults may indicate that pregnancy affects the LC-PUFA status of adults and adolescents in distinct ways.

Use of gas liquid chromatography in combination with pancreatic lipolysis and multivariate data analysis techniques for identification of lard contamination in some vegetable oils

A study was conducted to investigate the use of gas liquid chromatography (GLC) to identify lard (LD) contamination in palm oil (PO), palm kernel oil (PKO), and canola oil (CLO). Vegetable oils were deliberately adulterated with animal fats such as LD, beef tallow (BT), and chicken fat (CF) in varying proportions. In order to monitor the fatty acid (FA) compositional changes due to adulteration, GLC analyses of fatty acid methyl esters (FAME) were performed on 2-monoacylglycerol (2-MG) and neutral triacylglycerol (TAG) isolated from each sample. For the evaluation of FA data, multivariate statistical techniques were employed. The results showed that canonical discriminant (CANDISC) analysis was the most effective technique for discriminating LD-adulterated samples from those adulterated with other animal fats. Additionally, mathematical equations obtained by simple regression analysis could be used for quantification of LD contents in admixtures.

ChemInform Abstract: Asymmetrical [4 + 2]‐Cycloaddition of (‐)‐Menthyl Acrylate and (‐)‐Menthyl Methacrylate to Cyclopentadiene in the Presence of BBr3.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

Asymmetrical [4+2]-Cycloaddition of (-)-Menthyl Acrylate and (-)-Menthyl Methacrylate to Cyclopentadiene in the Presence of BBr3

An asymmetrical synthesis of bicyclo[2.2.1]hept-2-enes is described performed by [4+2]-cyclo-addition of (-)-menthyl acrylate, (-)-menthyl methacrylate to cyclopentadiene in the presence of BBr3.The effect of different factors on isomer composition, yield, and enantiomeric purity of the compoundsobtained was investigated. Kovatch indices were determined and boiling points were estimated with the use of gas-liquid chromatography.

An evaluation of methods for measurement of pesticides in sorption experiments

The concentration of four pesticides (2,4‐D, atrazine, phorate, and terbufos) in soil solution during sorption experiments was measured using UV spectrophotometry, Gas Liquid Chromatography (GLC), High Performance Liquid Chromatography (HPLC), and radiotracer technique. The presence of water soluble organic matter in soil solution interfered with the measurement of pesticide using the UV spectrophotometry. The use of GLC, HPLC, and radiotracer technique involving 14C gave a good estimate of the concentration of pesticide in soil solution. The pesticide remaining in soil can be quantitatively analyzed by extracting with a scintillation solution containing an organic solvent such as toluene or dioxane. Among the various centrifuge tubes glass tubes with Teflon caps sorbed negligible amount of pesticides and these tubes can be used for the sorption measurements.

Gas-liquid chromatography-mass spectrometry of primary and secondary fatty alcohols and diols as their tert.-butyldimethylsilyl derivatives

The use of gas-liquid chromatography (GLC) and mass spectrometry (MS) with derivatizing agents which give stable derivatives and informative fragmentation patterns allows for accurate identification of a variety of compounds. In this comprehensive study, the tert.-butyldimethylsilyl ( tBDMS) derivatives of saturated and unsaturated primary alcohols, iso-and anteiso-primary alcohols, branched alcohols, secondary alcohols and primary diols were produced and analyzed by GLC-MS. Most derivatized alcohols produced prominent mass minus 57 [M-57] + fragment ions, which, combined with their respective retention data and other key fragment ions, allows for their identification and analysis.

Use of gas-liquid chromatography with electron-capture and thermionic-sensitive detection for the quantitation and identification of pesticide residues

A gas chromatographic methodology that exploits combination of different columns and different detectors for testing residues of over 150 pesticides is proposed. Two gas-liquid chromatographs were set up each with two capillary columns of different polarities, DB-5 and DB-1701. Each column was connected to a precolumn with deactivated silica which was in turn connected to the injector. Each column was coupled to an electron-capture detector in one instrument and a thermionic-sensitive detector in the other. Standard solutions containing each pesticide, with ethion used as a reference peak to calculate the relative retention time (RRT), were injected into each gas chromatograph. RRT values for each column-detector combination are reported. Two columns of different polarities allowed identification and separation of most of the pesticides studied. Qualitative confirmations achieved by comparing the RRT values obtained by columns of different polarities on the same detectors as well as on different detectors are discussed. The instrumental configuration and the analytical conditions used may be a useful tool for the determination and confirmation of the great number of pesticides residues that may be extracted by multiresidue methods.

Use of gas-liquid chromatography in the analytical control of riklocain manufacture

Use of gas-liquid chromatography in the analytical control of riklocain manufacture

Use of gas-liquid chromatography for subgrouping coagulase-negative staphylococci during a nosocomial sepsis outbreak.

Gas-liquid chromatographic (GLC) fatty acid profile correlation analysis was applied for the subgrouping of 169 coagulase-negative staphylococci collected during an outbreak of nosocomial sepsis in a hematologic unit. The fatty acid profile similarity index between six ciprofloxacin-resistant Staphylococcus epidermidis septicemia strains was as high as 98.39 +/- 0.68, indicating a high degree of resemblance. This finding corroborated the finding by conventional typing methods that the isolates shared the same strain characteristics and, therefore, could be derived from the same epidemiological origin. Further, the GLC fatty acid profiles were analyzed for coagulase-negative staphylococcal cutaneous isolates recovered from colonization cultures of the patients and personnel in that same unit. The similarity index between 88 ciprofloxacin-resistant Staphylococcus epidermidis skin isolates with similar plasmid profiles was as high as 95.47 +/- 3.78, whereas the correlation coefficient between 45 ciprofloxacin-susceptible Staphylococcus epidermidis skin isolates with different plasmid profiles was only 85.23 +/- 10.82. Cluster analysis grouped the ciprofloxacin-resistant Staphylococcus epidermidis isolates into one distinct cluster, while most of the ciprofloxacin-susceptible Staphylococcus epidermidis isolates were grouped into two separate clusters. When compared with the plasmid profiling, the GLC method congruously grouped 127 (87%) of the 146 Staphylococcus epidermidis isolates, thereby suggesting its potential value in subgrouping coagulase-negative staphylococci during nosocomial outbreaks.

Chemical definition of an epitope/adhesin molecule on Candida albicans.

An antigen (Ag), as defined by reactivity with a monoclonal antibody (mAb 10G), was found on the cell wall surface and on the plasma membrane of Candida albicans yeast cells (Li, R. K., and Cutler, J. E. (1991) J. Gen. Microbiol. 137, 455-464). The 10G Ag from the cell surface location was solubilized by treatment with beta-mercaptoethanol and Zymolyase. Antigenic activity of the extract was lost following periodate oxidation, but was stable to proteolytic enzyme and heat treatments. Mannoproteins in the extract were fractionated by hexadecyltrimethylammonium bromide. A fraction containing the 10G Ag was degraded by mild acid hydrolysis and a tetrahexose eluted from a P-2 size exclusion column was found to be the epitope (10G epitope) part of the 10G Ag. By use of gas-liquid chromatography, mass spectroscopy, and H-1 proton NMR analysis, the 10G epitope was determined to be a linear beta-1,2-linked tetramannose. The 10G Ag, which was immunopurified from the Zymolyase extract, and the 10G epitope were involved in the attachment of C. albicans to mouse spleen marginal zone macrophages. Both the 10G Ag and the purified 10G epitope specifically inhibited C. albicans adherence in an ex vivo binding assay. Latex beads adsorbed with the 10G Ag or the 10G epitope adhered specifically to the splenic marginal zone macrophages. These data show that a beta-1,2-linked mannotetraose part of a C. albicans cell wall mannoprotein is an adhesin site that may play a role in pathogenesis of disseminated candidiasis.

Detection of intra-amniotic infection by gas-liquid chromatography.

The use of gas-liquid chromatography to detect short-chain organic acids in the amniotic fluid of patients with amnionitis has been previously described. Most of the studies describe patients in the early third trimester with such infections. The purpose of the current study was to confirm the correlation of infection with increased production of organic acids and to assess the effect of gestational age on the presence of these short-chain fatty acids in the amniotic fluid. Six patients with confirmed chorioamnionitis were used as positive control subjects. Seventy-two patients at various gestational ages from 18 to 42 weeks with negative Gram's stain and culture results from the amniotic fluid were used as negative control subjects. The data revealed an increased production of organic acids, particularly pyruvic, oxalic and succinic, in patients with amnionitis regardless of gestational age. Interestingly, patients with noninfected amniotic fluid also revealed an increase in the concentrations of volatile organic acids between 27 and 32 weeks' gestation. It appears from this study that previous results correlating chorioamnionitis with an increased production of organic acids in the amniotic fluid may have been confounded by gestational age.

Use of Gas Liquid Chromatography as an Adjunct to Conventional Bacteriological Methods in the Diagnosis of Anaerobic Cerebral Abscess

Forty cases of cerebral abscesses were studied prospectively to establish the microbial agents implicated in these cases. Chronic otitis media (14 patients, 35%), congenital heart disease (five patients, 12.5%),a and meningitis (five patients, 12.5%) were among the important predisposing factors. Streptococcus (14 patients, 35%) was the most common causative pre-isolated, the predominant species being Streptococcus milleri (11 patients, 27.5%). Other organisms isolated included Proteus mirabilis in six patients (15%) and Staphylococcus aureus in five patients (12.5%). Anaerobes (12 patients, 30%), predominantly Bacteroides sp. (eight patients, 20%), played an important role in these cases, the majority of which were isolated in mixed cultures. Gas-liquid chromatographic analysis of pus detected the presence of anaerobes in another 11 cases of cerebral abscess, in which cultures of anaerobes were negative. Therefore, gas-liquid chromotography is useful as an adjunct to conventional bacteriological methods in providing a rapid and sensitive means of detecting anaerobes in pus obtained especially from patients who had received antibiotic therapy prior to hospitalization.

Effect of Bismuth Subsalicylate on Chronic Diarrhea in Childhood: A Preliminary Report

Stools collected from 39 infants and children with chronic nonspecific diarrhea and from 10 age-matched controls were examined for bile acid content with use of gas-liquid chromatography. Values were correlated with stool color. Mean concentration of bile acids in green stools (7.7 +/- 1.52 mg/g dry weight) was significantly higher than that in brown stools (3.76 +/- 0.7 mg/g dry weight) and in control stools (1.42 +/- 0.35 mg/g dry weight). In patients with green diarrhea, treatments with cholestyramine and bismuth subsalicylate (Pepto-Bismol) were equally effective in decreasing stool frequency, with the latter being more effective in decreasing water content. Patients with brown stools had an insignificant response to therapy.

Condensation of model linear siloxane oligomers possessing silanol and silyl chloride end groups. The mechanism of silanol silylation by a chlorosilane in the presence of neutral nucleophiles

The condensation of pentamethyldisiloxane-1-ol ( 1) with 1-chloro-1-isopropyltetramethyldisiloxane ( 2) in methylene chloride solution has been studied as model of the polyheterocondensation of functional oligosiloxanes. The process catalysed by triethylamine, hexamethylphosphoroamide (HMPA) or some nitrogen heterocycles showed a high selectivity towards heterocondensation. Triethylamine promotes the reaction by acting as the base bonding to the incipient proton on the silanol group entering into the condensation. This mechanism of the catalysis by Et 3N was demonstrated by kinetic studies involving use of gas-liquid chromatography in conjunction with study of the hydrogen bonding by IR spectroscopy. In contrast, the kinetic data and the reactivity pattern indicate that N-heterocycles and HMPA catalyse the reaction by functioning as nucleophiles to form a transient complex with the chloride substrate. A mixture containing a highly nucleophilic N-heterocycle, triethylamine has no effect on the rate of the reaction, acting only as a HCl acceptor.

Variability in growth and fermentation products of Clostridium sporogenes inoculated into canned foods and grown in laboratory media for various time intervals

Previous studies on the use of gas-liquid chromatography (GLC) in solving food spoilage problems have proven the technique to be rapid, simple and inexpensive. However, the limitation of this approach is the effect of food composition on metabolic activity as reflected in the GLC profile of the organism involved. In this study, the influence of the food composition and incubation time upon the fermentation end-product patterns of Clostridium sporogenes was investigated. The results illustrated the fact that each of these environmental variables had a profound effect on the GLC profile. When the test organism was grown in peptone yeast (PY) medium with or without 1% glucose, the characteristic profile was detected only after 24 h which corresponds to the stationary phase of growth. An initial lag (12 h) of glucose utilization was observed. Glucose supplementation of the PY medium resulted in certain metabolic activities which are explained by reference to known physiological facts. Examples include the production of higher amounts of alcohol, especially ethanol, the production of iso-amyl alcohol and the suppression of certain branched chain amino acids. A proposal is made to show how the interaction of bacteria with environmental variables could be studied systematically.

New developments in the diagnosis of opportunistic fungal infection

This review considers recent developments in the diagnosis of aspergillosis, candidosis and cryptococcosis and discusses the prospects for routine application of a number of novel methods. The introduction of lysis-centrifugation and radiometric methods for blood culture has improved the diagnosis of deep candidosis, but the value of these methods for the diagnosis of aspergillosis has not yet been determined. Recent developments in serological diagnosis have included the evaluation of newly discovered antigens of Candida albicans in an attempt to distinguish colonization from significant infection. Antigen detection, an established method for the diagnosis of cryptococcosis, has also been evaluated and appears promising for the diagnosis of aspergillosis and candidosis. Another promising approach has been the use of gas-liquid chromatography to detect fungal metabolites in serum and other host fluids.

Use of gas liquid chromatography in the clinical diagnosis of anaerobic pleuropulmonary infection

Evidence of anaerobic infection was sought in 83 patients with pulmonary disease with anaerobic culture and gas liquid chromatography (GLC) of mucopurulent sputum, or pleural fluid where appropriate. Saliva samples from nine healthy controls and 14 patients with cystic fibrosis were examined by the same methods to assess anaerobic content. Clinically significant anaerobic pleuropulmonary infection was not found in our patients with bronchitis, bronchiectasis and cystic fibrosis and occurred in only some of our patients with empyema and lung abscess. GLC of pleural fluid (empyema) or sputum (lung abscess) was helpful in identifying these cases, when a strongly positive reading was obtained. The gas liquid chromatogram was negative or only weakly positive in those patients where the presence of anaerobes was clinically insignificant, most probably resulting from contamination of the sputum samples by saliva. Results were rapidly available and the need for transtracheal aspiration to obtain specimens of bronchial secretion uncontaminated by mouth flora was avoided. The semiquantitative GLC would therefore appear to be a useful method for investigating specimens from patients with suspected anaerobic pleuropulmonary infection.

Contagious equine metritis--use of gas liquid chromatography in identifying the causal agent.

Cellular fatty acid compositions of contagious equine metritis isolates and three reference Haemophilus equigenitalis cultures were determined by gas chromatography. The chromatographic data were standardised and normalised fatty acid methyl ester (FAME) profiles were produced. The profiles were compared visually and similarity indices were determined using a computer peak matching method. There was little difference between the profiles of the three reference strains, each strain being characterised by three major fatty acids; C 18:1, C 16:0 and 30H-C 14:0. Variations in cultural conditions had no significant effect on the FAME profiles. The identification of laboratory isolates using the technique was in agreement with the presumptive identification based on the currently recommended tests and an improvement on the confirmatory serological identification. The FAME profiles provided confirmation of identity where it was not possible to use the presently recommended serological procedures. The authors recommend the gas chromatography technique for use in the diagnostic laboratory as an adjunct to the presently accepted identification methods.

Use of Gas-Liquid Chromatography to Determine the End Products of Growth of Lactic Acid Bacteria

A simple gas-liquid chromatographic procedure for analyzing ethanol, acetic acid, acetoin, and racemic and meso-2,3-butylene glycol in broth media is described. Overnight broth cultures were filtered or centrifuged, and the filtrate or supernatant was treated with formic acid to aid separation of volatile fatty acids. Samples were then directly analyzed by gas-liquid chromatography on a 20% Tween 80-Chromosorb W-AW column and propionic acid as an internal standard. A complete analysis took ca. 8 min. The method can be used to distinguish homofermentative from heterofermentative lactic acid bacteria based on the level of ethanol produced and citrate-utilizing from non-citrate-utilizing lactic acid bacteria based on the levels of acetic acid produced. The method also has potential in distinguishing other bacterial fermentations. Of the 13 species of lactic acid bacteria tested, Streptococcus lactis subsp. diacetylactis was the major producer of 2,3-butylene glycol (total range, 0.3 to 3.5 mM), and, except for strain DRC1, both the racemic and meso isomers were produced in approximately equal amounts.