Gas-liquid Chromatographic Technique Research Articles

A minor source of vernolic, malvalic, and sterculic acids inPithecollobium dulce (syn.Inga dulcis ) seed oil

Pithecollobium dulce, Benth (syn.Inga dulcis, Willd) seed oil, belonging to the Leguminosae plant family, contains minor amounts of vernolic acid (12,13-epoxy-octadec-cis-9-enoic acid, 10.0%), malvalic acid [7-(2-octacyclopropen-1-yl)heptanoic acid, 3.2%], and sterculic acid [8-(2-octacyclopropen-1-yl)octanoic acid, 2.0%]. The other normal fatty acids are palmitic (12.1%), stearic (4.2%), behenic (10.6%), oleic (34.1%), and linoleic (23.8%). These fatty acids have been characterized by Fourier transform infrared,1H nuclear magnetic resonance, mass spectrometry and gas-liquid chromatography techniques and by chemical degradations.

Determination of Infinite Dilution Activity Coefficients and 1-Octanol/Water Partition Coefficients of Volatile Organic Pollutants

The characterization of pollutants is of growing interest as concerns about the environment increase. One parameter useful in predicting the fate of a chemical in the environment, the infinite dilution activity coefficient, has been determined here for several EPA priority pollutants in 1-octanol at 25 C using a relative gas-liquid chromatographic measurement technique. A simple correlation has been developed relating the limiting activity coefficients of a species in pure water and in pure 1-octanol to its octanol/water partition coefficient. Agreement between the experimental results and published values is very good. The method developed here of computing the octanol/water partition coefficient from gas chromatographic measurements of its infinite dilution activity coefficients is an improvement over traditional partition coefficient determination methods in that it is easier and quicker, without a loss of accuracy. Furthermore, the authors show that this method is applicable to chemicals covering a large range of hydrophobicities (1.0 < log K[sub OW] < 5.0).

A fuzzy information approach to integrating different transformer diagnostic methods

Methods for identifying transformer fault conditions include dissolved gas analysis, liquid chromatography, acoustic analysis, and transfer function techniques. Researchers have applied artificial intelligence concepts in order to encode these diagnostic techniques. These attempts have failed to fully manage the inherent uncertainty in the various methods. A theoretical fuzzy information model is introduced. An inference scheme which yields the most consistent conclusion is proposed. A framework is established that allows various diagnostic methods to be combined in a systematic way. Numerical examples demonstrate the developed system. >

Measurement of serum arabinitol by gas-liquid chromatography: limitations for detection of systemic candida infections.

The measurement of serum arabinitol in the diagnosis of systemic candidosis was evaluated using a gas-liquid chromatography technique in a cohort of at risk patients. The prevalence of seropositivity was low and did not correlate with evidence of infection. This technique is unlikely to achieve acceptance because it does not discriminate between patients with and without infection; it requires specialised equipment and it is expensive.

PHARMACOKINETICS OF LIGNOCAINE IN CHILDREN AFTER INFILTRATION FOR CLEFT PALATE SURGERY

We have studied the pharmacokinetics of lignocaine in children after local infiltration for cleft palate surgery. After induction of anaesthesia, lignocaine 2.5 mg kg-1 with adrenaline 1:200,000 was injected into the palate. Blood samples were collected before and at 2, 5, 10, 15, 20, 30, 60 and 120 min after infiltration. Plasma concentrations of lignocaine were measured by a gas-liquid chromatographic technique. There were no signs of systemic toxicity on routine monitoring of the patients and the peak plasma concentrations were less than the accepted toxic values. Mean half-life was 72.9 (SEM 9.9) min, similar to that found previously in adults and children. However differences in mean clearance (24.6 (2.04) ml kg-1 min-1) and volume of distribution (0.80 (0.07) litre kg-1) were found between this and previous studies.

ASSESSMENT OF GLUCOSINOLATES IN BROCCOLI BY THREE DIFFERENT METHODOLOGIES

ABSTRACT Three different methodologies were used to assess the glucosinolate content in four broccoli cultivars. The assessment was performed by the thymol, enzyme immobilization and gas liquid chromatography (GLC) techniques. The cultivars used were Green Valiant, Green Duke, Marathon and Samurai. The three techniques demonstrated that Samurai and Green Valiant were the cultivars with the highest content of glucosinolates. It was also evident that, compared to stem and leaves, the floret of the four cultivars exhibited in general the highest amount of this component. Of the tested methodologies, the GLC technique showed the lowest data variability, although this technique was unable to estimate all the glucosinolates present in the broccoli samples because of its poor performance for the quantitation of indole and sulfinyl glucosinolates. In conclusion, the thymol technique appeared the most adequate procedure for the assessment of glucosinolates in broccoli samples.

Influence of microwave heating on the stability of processed samn

Butter was converted to samn by microwave and conventional heating. The quality of the processed samn by the two methods was followed by determining the acid, peroxide and TBA values over a period of six weeks at 60°C. The fatty acid composition of samn samples was determined by gas-liquid chromatographic technique. The data show that butter conversion to samn by microwave heating was accomplished in about one half of the time that conventional heating requires. Microwave heating obviously increased the development of samn rancidity compared with the conventional heating. The parameters used for measuring lipid rancidity indicated that the main cause of samn rancidity under the present conditions is an oxidation mechanism.

Gas Liquid Chromatographic Analysis of DDT Residues in the Kidney of Labeo rohita

AbstractLaboratory acclimated Labeo rohita, common fresh water edible fish, were exposed to a sublethal concentration (2.5 ppm) of DDT for 2, 4, 8, 16 and 32 days. Residues of three isomers of DDT were estimated in the kidney of Labeo rohita using the gas liquid chromatographic technique. The maximum residues of DDT, DDE and DDD were 1.4327, 0.4172 and 0.2913 ppm, respectively. The total DDT residues concentration was 2.1412 ppm on the final day of the experiment. The tabulated tcalculated t at all intervals.

Chromatographic separations of sucrose monostearate structural isomers

High-performance liquid chromatography (HPLC), thin-layer chromatography (TLC) and gas—liquid chromatography (GLC) methods are described for separating sucrose monostearate isomers. The HPLC procedure provides baseline separation of purified monoester isomers into three main peaks at room temperature, and completely separates monoesters with different acyl chain lengths (C 14, C 16, C 18). The TLC method separates up to six of the eight possible positional monostearate isomers, which can be further differentiated by specific color development with a visualizing agent. The GLC technique used resolves monoesters with different acyl chain lengths, and partially separates monostearate isomers. Isomers collected from HPLC were subjected to treatment with invertase, then resolved and detected by TLC to determine fatty acid substitution patterns on the sucrose molecule.

Carnitine Ester Excretion in Pediatric Patients Receiving Parenteral Nutrition

Carnitine plasma concentrations and the excretion of carnitine and individual carnitine esters were determined in 25 children and adolescents with gastrointestinal diseases receiving carnitine-free parenteral nutrition for at least 1 mo using radiochemical and radioisotopic exchange HPLC methods. Children less than 12-y-old usually had carnitine plasma concentrations less than -2 SD from the normal mean for age, whereas patients greater than 12-y-old had carnitine plasma concentrations within the normal range. Age was the only variable to correlate significantly with plasma carnitine concentrations during parenteral nutrition. Free carnitine (FC) excretion was closely correlated with plasma FC concentrations and minimal at values less than 25 mumols/L. The excretion of FC and short-chain acylcarnitines was reduced by an order of magnitude in younger compared with older patients and controls, but the excretion of "other" acylcarnitines was less affected. Some of the latter were tentatively identified using gas-liquid chromatographic and mass spectroscopic techniques as unsaturated and/or branched medium-chain carnitine esters with a carbon chain of C8-C10. The results suggest that FC and short-chain acylcarnitine are conserved by the kidney in nutritional carnitine deficiency but that there may be an obligatory renal excretion of other carnitine esters that contributes to the development of hypocarnitinemia in the younger age group.

Carnitine Ester Excretion in Pediatric Patients Receiving Parenteral Nutrition

ABSTRACT: Carnitine plasma concentrations and the excretion of carnitine and individual carnitine esters were determined in 25 children and adolescents with gastrointestinal diseases receiving carnitine-free parenteral nutrition for at least 1 mo using radiochemical and radioisotopic exchange HPLC methods. Children <12-y-old usually had carnitine plasma concentrations <-2 SD from the normal mean for age, whereas patients >12-y-old had carnitine plasma concentrations within the normal range. Age was the only variable to correlate significantly with plasma carnitine concentrations during parenteral nutrition. Free carnitine (FC) excretion was closely correlated with plasma FC concentrations and minimal at values <25 μmol/L. The excretion of FC and short-chain acylcarnitines was reduced by an order of magnitude in younger compared with older patients and controls, but the excretion of “other” acylcarnitines was less affected. Some of the latter were tentatively identified using gas-liquid chromatographic and mass spectroscopic techniques as unsaturated and/or branched medium-chain carnitine esters with a carbon chain of C8-C10. The results suggest that FC and short-chain acylcarnitine are conserved by the kidney in nutritional carnitine deficiency but that there may be an obligatory renal excretion of other carnitine esters that contributes to the development of hypocarnitinemia in the younger age group.

Rapid diagnosis of tuberculous meningitis by frequency-pulsed electron-capture gas-liquid chromatography detection of carboxylic acids in cerebrospinal fluid

The frequency-pulsed electron-capture gas-liquid chromatography technique described previously by Brooks et al. was modified and applied to the studies of coded and routine clinical specimens. Uncentrifuged cerebrospinal fluid (2 ml) was extracted under acidic conditions, derivatized, and analyzed by frequency-pulsed electron-capture gas-liquid chromatography on large-bore fused silica polar and nonpolar capillary columns. The frequency-pulsed electron-capture gas-liquid chromatography profile of carboxylic acids (C2 through C22) along with identification of tuberculostearic acid, established by retention time comparison of derivatized tuberculostearic acid and derivatized sample extract, strongly suggests the presence of Mycobacterium tuberculosis in patients with lymphocytic meningitis. Results from 41 coded cases and 75 clinical cases showed that the frequency-pulsed electron-capture gas-liquid chromatography test had a specificity of 91% and a sensitivity of 95%.

Suppression of tricarboxylic acid cycle in Escherichia coli exposed to sub-MICs of aminoglycosides

The metabolic activity of Escherichia coli ATCC 25922 challenged with sub-MICs of aminoglycosides was analyzed with a batch calorimeter. High-performance and gas-liquid chromatographic techniques were utilized to evaluate the concentrations of metabolic reactants, intermediates, and end products. The data reported indicate that aminoglycosides inhibit or delay bacterial catabolism of carboxylic acids, with the following relative degrees of activity: amikacin greater than gentamicin greater than sisomicin greater than netilmicin greater than kanamycin. The decrease in total biomass production was proportional to the degree of tricarboxylic acid cycle inhibition.

Digestion of fibre polysaccharides of pea (Pisum sativum) hulls, carrot and cabbage by adult cockerels

Characterization of the carbohydrates of pea (Pisum sativum) hulls, carrot and cabbage using both colorimetric and gas-liquid chromatographic techniques permitted a detailed investigation into the extent of digestion of differing types of fibre. These digestion studies were greatly aided by the development of a rapid bioassay employing starved adult cockerels. Total collection of undigested residues, uncontaminated by food spillage, could be made from trays placed under the cockerels. Chemical analysis showed that pea hulls consisted mainly of fibre with very little available carbohydrate present, whereas more than half of freeze-dried carrot and cabbage consisted of available carbohydrate (sucrose, glucose, fructose, starch) and consequently considerably less fibre was present. The fibre of carrot and cabbage was similarly composed of nearly equal amounts of neutral and acidic polysaccharides, whereas pea-hull fibre had four times as much neutral as acidic polysaccharides. The digestibility of total neutral polysaccharides from all three foodstuffs was extremely low. However, there appeared to be preferential digestion of polysaccharides composed of rhamnose, arabinose and galactose residues, all associated with pectic material, in contrast to the indigestibility of polysaccharides composed of fucose, xylose and glucose. Acidic polysaccharides were digested to a greater extent than neutral ones, and those of carrot and cabbage more so than pea hulls. The polysaccharides which were the most soluble were also the most digestible, but due to the arbitrariness of polysaccharide solubility, quantification of their total digestibility per se was considered not possible.

Changes in whole body lipid composition in a murine model of insulin-dependent diabetes mellitus

To assess the effect of experimentally induced insulin-dependent diabetes mellitus (IDDM) on total body lipid composition, homogenates of neonatal (0-day) and 6-day Sprague-Dawley rat pups treated on day 0 with 65 mg/kg body weight of streptozotocin (STZ) or citrate buffer alone were compared using thin-layer and gas-liquid chromatographic techniques. STZ-treated littermates in a parallel study were markedly hyperglycemic, hypoinsulinemic and attained only 50% of the gain in weight of citrate-treated controls. Although both groups were similar in protein to body weight ratios, STZ-treated pups exhibited 60% of the total lipid content of citrate-treated littermates when compared by weight. The decrease in total lipid content in the STZ-treated group resulted specifically from decreased neutral and not phospholipid content, although a small increase in phosphatidic acid and sphigomyelin was observed in this group. The changes in relative whole body lipids with short-term, high-dose STZ parallel those reported in human IDDM.

Lipid composition of four species of amphistomes (Trematoda) from the rumen of cattle

Awharitoma A.O., Opute F.I., ali S.N. and obiamiwe B.A. 1988. Lipid composition of four species of amphistomes (Trematoda) from the rumen of cattle. International Journal for Parasitology 18: 441–444. Lipids of four amphistome species Carmyerius minutus, Ceylonocotyle dicranocoelium, Cotylophoron cotylophorum and Paramphistomum microbothrium from the rumen of cattle were investigated by the combined techniques of column, thin-layer and gas-liquid chromatography. Total lipid values (% wet weight) obtained were for C. minutus 2.72%, C. dicranocoelium 3.23%, C. cotylophorum 4.42% and P. microbothrium 3.49%. Neutral lipids accounted for 20–34% and phospholipids 64–79% of total lipids. The major neutral lipid component of the four parasites was cholesterol. Among the phospholipids phosphatidyl choline and phosphalidyl ethanolamine predominated. The four amphistomes showed similar fatty acid profiles, with chain length varying from 12 carbon atoms to 20 carbon atoms. The level of Unsaturation in the fatty acids of the four parasites was over 50%. Lipid classes and fatty acids from the host rumen tissue and rumen content were qualitatively similar to those of the parasites, thus emphasizing nutritional dependence of the parasites on their host.

Neutral sugar composition of extracellular polysaccharides produced by strains of Butyrivibrio fibrisolvens.

The extracellular polysaccharides (EPSs) produced by 37 isolates presently classified as Butyrivibrio species (or more specifically as Butyrivibrio fibrisolvens) were purified from glucose-grown cultures. The neutral sugar compositions of these EPSs were determined by both thin-layer and gas-liquid chromatographic techniques. Results showed that while the neutral sugar composition of the EPS was constant for a given strain, it varied considerably between strains. In addition, several acidic components in the EPS, of both known and unknown structure, were detected artifactually as acetylated lactones, the acetylated alditols derived from these lactone(s), or both. Two novel components, L-altrose and the acidic sugar 4-O-[1-carboxyethyl]-D-galactose, were common constituents of the EPS from some strains of B. fibrisolvens. These and other EPS compositional features were used to sort isolates of B. fibrisolvens into groups which may have taxonomic significance. A scheme for sorting isolates into these groups, and the relative relationships between groups, is proposed.

Gas-Liquid Chromatographic Determination of Propionic Acid Production Differentiates between the Food-Poisoning Strains and Toxigenic-Type Strains of Clostridium perfringens

Fatty acids of 32 strains belonging to five types of Clostridium perfringens were extracted from the supernatant liquid of cultures in various different media prepared with or without the addition of sugar and examined by application of the gas-liquid chromatographic technique. The major products in nearly all media were acetic, propionic and butyric acid among the volatile fatty acids and only lactic acid among the nonvolatile fatty acids. Quantitative comparison of the resulting chromatograms with regard to the presence and relative amounts of propionic acid as one of the large major peaks revealed clear differences between the toxigenic types and the food-poisoning strains of this organism. In cooked meat medium containing 2% fructose, all the toxigenic-type strains produced propionic acid, but the food-poisoning strains tested entirely lacked production of this acid. This differentiation characteristic may be useful in routine laboratory bacteriology.

Metabolism of tridiphane (2-(3,5-dichlorophenyl)-2(2,2,2-trichloroethyl)oxirane) by hepatic epoxide hydrolases and glutathione S-transferases in mouse

The transformation of the herbicide tridiphane (Tandem, Dowco 356, 2-(3,5-dichlorophenyl)-2(2,2,2-trichloroethyl)oxirane by the epoxide-metabolizing enzymes, epoxide hydrolases (EH) and glutathione S-transferases (GST), was investigated in mouse liver microsomes and cytosol. The microsomal EH catalyzed the formation of tridiphane diol. The production of this metabolite was prevented by cyclohexene oxide at 1 m m, a known inhibitor of microsomal EH. The structure of the diol was verified by comparison of retention time or R f of the compound with those of an authentic standard using gas-liquid chromatography or thin-layer chromatography techniques. The diol formed a diester with 1-butane boronic acid or an aldehyde with lead tetraacetate. Mass spectral analysis supported the structural assignment. After optimization of the assay conditions, kinetic constants for the hydration of tridiphane by the microsomal EH were determined ( K m = 65 μ m and V max = 0.9nmol/min/mg protein). Dietary exposure of mice to the hypolipidemic drug clofibrate at a dose of 0.5% (w/w) for 2 weeks increased by 173% the metabolism of tridiphane to tridiphane diol by the microsomal fraction. No diol could be detected following incubation of tridiphane with the cytosolic EH, even after induction by clofibrate. Tridiphane was also a substrate for GST, but administration of clofibrate did not change the specific activity for the formation of the glutathione conjugate. The herbicide was a rather weak inhibitor of the microsomal EH and the cytosolic GST activities measured with cis-stilbene oxide and trans-stilbene oxide as substrates with I 50's of 3.0 × 10 −5 and 1.8 × 10 −4 m, respectively. Tridiphane diol was a poor inhibitor of the enzymes studied, and the glutathione conjugate of tridiphane caused marked inhibition of only the GST activity (I 50, 2.0 × 10 −5 m). By contrast the activity of cytosolic EH ( trans-stilbene oxide) was relatively insensitive to the addition of tridiphane or of tridiphane metabolites.

Drug accumulation in lung fluid of the fetal lamb after accumaternal or fetal administration

The pharmacokinetic characteristics of the antiemetic drug metoclopramide and the antihistamine diphenhydramine have been determined in a chronically catheterized pregnant sheep preparation. Metoclopramide and diphenhydramine were administered by separate maternal and fetal intravenous infusions to a steady state as well as by maternal intravenous bolus dosing. Drug concentrations in the maternal and fetal plasma and the amniotic and tracheal fluids were measured by means of capillary gas-liquid chromatographic assay techniques. Both metoclopramide and diphenhydramine were excreted into tracheal fluid in substantial quantities. Tracheal metoclopramide concentrations were found to exceed fetal plasma levels by about fifteen-fold while diphenhydramine attained maximal excretion in tracheal fluid of about five times that seen in fetal plasma. Drug levels were observed to accumulate slowly in amniotic fluid and eventually to exceed tracheal concentrations. The markedly elevated concentrations of these drugs in fetal lung fluid suggests that the fetal lung may be an important route of drug distribution, elimination, and excretion.