Gas-liquid Chromatographic Studies Research Articles

Updated Definition of the Three Solvent Descriptors Related to the Van der Waals Forces in Solutions

Innovative viewpoint on the older topic of the van der Waals forces, is of interesting and significant issue to be concerned in both the fields related to the fundamental investigation and thus valuable in guiding the new physiochemical phenomena and processes for both academic research and practical applications. The intermolecular Van der Waals forces involved in solutions have been recently deeply reconsidered as far as the solute side is concerned. More precisely, the solute descriptors (or parameters) experimentally established, have been accurately related to molecular features of a Simplified Molecular Topology. In the present study, an equivalent result is reached on the solvent side. Both experimental parameters have been obtained simultaneously in previous Gas Liquid Chromatographic studies for 121 Volatile Organic Compounds and 11 liquid stationary phases, via an original Multiplicative Matrix Analysis. In that experimental step, five groups of forces were identified, two of hydrogen bonding and three of Van der Waals: 1) dispersion (London), 2) orientation or polarity strictly speaking (Keesom), and 3) induction-polarizability (Debye). At this stage, an attempt of characterization the solvent parameters via the SMT procedure has been limited to those related to the Van der Waals forces, those related to the hydrogen bonding being for now left aside.

The oil and gas potential of the Kuma rocks of the Bakhchisarai region of Crimea

The oil and gas potential of the Kuma Formation of the Bakhchisarai region (southwestern Crimea) was substantiated on the basis of a lithological and micropaleontological study of the rocks of the section of the formation and geochemical (luminescent-bituminous, gas-liquid chromatographic, pyrolytic, and isotope) studies of the organic matter of the rocks. New regions for study that are favorable for the origination of the oil system in this formation were identified.

Fatty acid composition of Goniobasis virginica, Physa sp. and Viviparus malleatus (Mollusca: Gastropoda) from Lake Musconetcong, New Jersey

Gas—liquid chromatographic studies were done to determine the fatty acid composition of Goniobasis virginica Physa sp., and Viviparus malleatus (Mollusca: Gastropoda), from Lake Musconetcong, NJ, U.S.A. Palmitic acid was the predominant saturated fatty acid, followed by stearic acid, in all three molluscan species. The chief monoenes were 16:n−7, 18:1n−7; 20:1n−11+9, and 22:1n−11+13, which together accounted for all monoene fatty acids and one-quarter of the total fatty acids. Considerable amounts of linolenic acid (2.7−4.1%) and arachidonic acid (7.8−12%) were found in all three species. The percentage composition of docosahexaenoic acid (22:6n−3) was low compared to that of eicosapentaenoic acid (22:5n−3). Non-methylene interrupted dienes (20:2 NMID), characteristic of marine molluscs, ranged from 2 to 3% in the three species of freshwater snails.

Fatty acid composition of Biomphalaria glabrata (Gastropoda: planorbidae) experimentally infected with the intramolluscan stages of Echinostoma caproni (Trematoda)

1. 1. Gas-liquid chromatographic studies were done to determine the fatty acid composition of Biomphalaria glabrata snails experimentally infected with the intramolluscan stages of the trematode Echinostoma caproni. 2. 2. The infection reduced the amounts of saturated fatty acids in whole snail bodies, but increased the amounts of these acids in the digestive gland-gonad (DGG) complex of the snails. 3. 3. The infection increased markedly the amounts of palmitoleic acid (16:1 n − 9), but reduced the amounts of 16:1n − 7, 20:1n − 11 + 9 and 22:1n − 11 + 13 in both whole snail bodies and the DGG. 4. 4. The infection increased markedly the amounts of 20:2 non-methylene-interrupted diene (NMID) in both whole snail bodies and the DGG. 5. 5. Docosahexaenoic acid (DHA) concentration was markedly increased in infected whole snail bodies.

Fatty acid composition of Echinostoma trivolvis (Trematoda) rediae and adults and of the digestive gland-gonad complex of Helisoma trivolvis (Gastropoda) infected with the intramolluscan stages of this echinostome.

Gas-liquid chromatographic studies were done to determine the fatty acid composition of the digestive gland-gonad (DGG) complex of Helisoma trivolvis snails infected with the intramolluscan stages of Echinostoma trivolvis, of rediae freed from the DGG, of uninfected DGG, and of 41-day-old adult worms grown in golden hamsters. The DGG of infected snails showed significantly higher levels of stearic acid (18:0), hexatrienoic acid (16:3n-4), and docosahexanoic acid (22:6n-3) than that of uninfected snails. However, the DGG of uninfected snails showed significantly higher levels of 20:2 non-methylene-interrupted diene (NMID) and adrenic acid (22:4n-6) than that of infected snails. The profiles of other fatty acids were remarkably similar in both infected and uninfected snails. Adult worms showed significantly higher amounts of numerous saturated fatty acids and dienes as compared with the rediae. However, the rediae showed significantly higher amounts of certain monoenes and trienes as compared with the adults. Fatty acid differences between rediae and adults probably reflect differences in either the available lipid pools in the immediate host sites or the metabolic activity of each stage of this echinostome.

Fatty acid composition of two strains of Helisoma trivolvis (Gastropoda)

Gas-liquid chromatographic studies were done to determine the fatty acid composition of total lipids, triacylglycerols, and phospholipids of two strains of Helisoma trivolvis snails maintained on a lettuce-tetramin diet, Linolenic (18:3), oleic (18:1), palmitic (16:0), and linoleic (18:2) accounted for about 50% of the Tetramin diet, Linolenic (18.3), oleic (18:1), palmitic (16.0), and linoleic (18:2) accounted for about 50% of the fatty acids in the total lipids of both the Colorado (CO) and Pennsylvania (PA) strains. In the Colorado strain, about 50% of the fatty acids in the triacylglycerol fraction consisted of linolenic (18:3), palmitic (16:0), and eicosodienoic (20:2) acids; in the Pennsylvania strain, linelenic (18:3), palmitic (16:2), and oleic (18:1) acids made up about 50% of this fraction. The following fatty acids comprised about 50% of the phospholipids in the Colorado strain: linolenic (18:3), lauric (12:0),linoleic (18:2), eicosodienoic (20:2) and palmitic (16:0); linolenic (18:3), lauric (12:0) myristic (14:0), stearic (18:0), and eocosodienoic (20:2) made up about the same percentage of the phospholipid fatty acids in the Pennsylvania strain. Significant differences, both qualitatively and quantitatively, were seen in some of the fatty acids identified in this study, supporting the contention that lipid profiles may be useful in the chemotaxonomy of related strains of snails.

Fatty acid composition of Biomphalaria glabrata (gastropoda: Planorbidae) fed hen's egg yolk versus leaf lettuce

1. 1. Gas-liquid Chromatographic studies were done to determine the fatty acid composition of Biomphalaria glabrata snails fed either hen's egg yolk or leaf lettuce for 1 week. 2. 2. Oleic(18:l), palmitic (16:0) and linoleic (18:2) accounted for almost 70% of the fatty acids in the yolk-fed snails; palmitic (16:0), linoleic (18:2), arachidonic (20:4), stearic (18:0), isomers ofoleic (18:1), eicosanoic (20:1) and oleic (18:1) comprised about 60% of the fatty acids in the lettuce-fed snails. 3. 3. The percentage composition of palmitic (16:0), oleic (18:1) and linoleic (18:2) acids was significantly greater in yolk- versus lettuce-fed snails; the percentage composition of myristoleic (14: 1), heptadecanoic (17:0), heptadecenoic (17:1), linolenic (18:3), eicosanoic (20:1), eicosodienoic (20:2), eicosotrienoic (20:3), arachidonic (20:4), docosapentenoic (20:5), docosadienoic (22:2) and docosatrienoic (22:3) was significantly greater in lettuce- versus yolk-fed snails. 4. 4. Dietary lipids influence markedly the fatty acid composition of Biomphalaria glabrata snails.

Effects of Echinostoma trivolvis (Trematoda) infection on neutral lipids, sterols, and carotenoids in Helisoma trivolvis (Gastropoda)

1. 1. Histochemical, thin layer and gas-liquid chromatographic studies were done on neutral lipids, sterols and carotenes in the digestive gland-gonad (DGG) complex of Helisoma trivolvis infected with Echinostoma trivolvis vs uninfected DGG. 2. 2. Hitochemical Oil Red O staining showed the presence of neutral lipids in the redial body wall and in the digestive cells of the DGG. 3. 3. TLC showed that free sterols and triacylglycerols were major neutral lipid fractions along with lesser amounts of steryl esters and free fatty acids in the DGG of both populations. The percentage composition of all neutral lipid fractions was greater in infected than uninfected DGG. 4. 4. Infected DGG contained more carotenoid fractions than uninfected DGG, but only beta-carotene was identified from both. 5. 5. GLC studies showed that the major sterol present in snail DGG was cholesterol (about 70%) along with lesser amounts of stigmasterol, campesterol, beta-sitosterol and desmosterol. No clear cut distinction was seen in sterols from infected vs uninfected DGG.

Lipids and sterols in Corbicula fluminea (bivalvia)

Abstract 1. 1. Gravimetric, histochemical, thin-layer- and gas-liquid chromatographic studies were done on lipids and sterols in fresh and starved Corbicula fluminea clams. 2. 2. Gravimetric analysis showed no significant difference in the mean percent lipid of fresh clam bodies (2.2%) versus starved (2.9%). 3. 3. Qualitative thin-layer chromatography (TLC) showed that the main neutral lipid fractions in both fresh and starved clam bodies were free sterols and triacylglycerols along with lesser amounts of sterol esters and free fatty acids. Qualitative differences were not seen in fresh versus starved clams. 4. 4. Quantitative densitometric TLC showed no significant difference in the mean per cent of free sterols in fresh clam bodies (0.09%) versus starved (0.11%). 5. 5. Gas-liquid chromatographic analysis showed cholesterol as the main sterol (61.2%) with lesser amounts of campesterol, β-sitosterol, stigmasterol, and other minor sterols. 6. 6. Oil Red O histochemistry showed the presence of neutral lipids in the visceral mass and gills of both fresh and starved clams.

Chromatography : IV. Gas—liquid chromatographic studies of C 2C 6n-alkyl and C 3C 6 isoalkyl acrylates and their hydrogen halide and halogen addition derivatives

The retention behaviour of C 1C 6 n-alykyl and C 3C 6 isoalkyl acrylates and their mono- and dihalogen addition derivatives was examined isothermally at 100°C on squalane, OV-101, SE-54, UCON LB-550-X and SP-1000 capillary columns. The retention increments, showing the effect of derivation involving hydrogen halide and halogen addition in the acyl chain and the effect of methylene substitution in the alkyl chain, are presented.

Frequency-pulsed electron-capture gas—liquid chromatographic studies of chemical changes in sera of patients with schistosomiasis

Sera from well documented cases of Schistosoma mansoni and S. haematobium infections as well as controls, were studied by frequency-pulsed electron-capture gas—liquid chromatography (FPEL-GLC) and mass spectrometry for detection of carboxylic acids and amines. Many carboxylic acids and unidentified peaks were detected. In a few serum specimens from infected patients, putrescine and cadaverine were detected. Indications are that in these few patients with high egg counts enough diamines were present to possibly produce amine toxicity. Following the initial investigation, the basic chloroform extractions, which contained amines, were further studied by FPEC-GLC with the aid of splitless injection and a capillary column. Several amines were detected which seemed to be related to schistosomiasis. Mass spectra were obtained on an unidentified schistosamine peak. The possible significance of the data is discussed.

Low adrenal androgenic-anabolic steroids in women with rheumatoid arthritis (RA): Gas-liquid chromatographic studies of RA patients and matched normal control women indicating decreased 11-deoxy-17-ketosteroid excretion

Using GLC, multiple adrenal corticosteroid urinary metabolites, including androgenic-anabolic, glucocorticoid, pregnanediol, and pregnanetriol, were measured in eight ambulatory female RA patients and eight matched normal control subjects on baseline, ACTH-, and metyrapone-stimulation days under carefully monitored clinical research center protocol. Neither group had been treated previously with any steroid hormones. The 11-deoxy-17-KS metabolites, derived from adrenal androgenic-anabolic steroids, and comprising androsterone, etiocholanolone, and DHA, were significantly lower in RA patients on baseline (P less than .001), ACTH (P less than .005)-, and metyrapone (P less than .02)-stimulation days. To the contrary, the 11-oxy-17-KS metabolites, derived mainly from glucocorticoids, showed some lowered excretion at baseline (P less than .05), but none on ACTH- or metyrapone-stimulation. RA patients had lower tetrahydrocortisone (P less than .001) and tetrahydro-11-deoxycortisol (P less than .01) excretion at baseline, but not during ACTH- or metyrapone-stimulation, than control subjects. Pregnanetriol excretion was lower (P less than .005) in RA patients than control subjects only during ACTH-stimulation. No difference was found between groups in tetrahydrocortisol or pregnanediol excretion on any day studied. Under conditions of oral metyrapone administration (750 mg every four hours for seven doses) each control subject increased their DHA excretion, but no RA patient showed an increase over baseline excretion (P less than .02). Except for 11-deoxy-17-KS, no difference was found in the other metabolites studied during metyrapone stimulation, ie, pregnanediol, pregnanetriol, tetrahydro-11-deoxycortisol, and tetrahydrocortisol. The 24-hour oral metyrapone test provided a greater stimulus to total 11-deoxy-17-KS excretion than an eight-hour intravenous ACTH test in control and particularly RA (P less than .01) subjects even though the DHA excretion decreased in the RA groups. Our findings of lower adrenal androgenic-anabolic metabolite excretion in female RA patients than normal matched control subjects under various conditions and other supportive androgenic hormone and metabolite studies reviewed in the English reports suggest an abnormality of adrenal androgen synthesis or metabolism in RA, whether it be a primary predisposing or secondary factor in disease. The recognized female sex preponderance and age-specific patterns of occurrence of RA are consistent with adrenal androgenic function in adrenarche, adrenopause, and later changes in aging. Metabolite excretion patterns at baseline, ACTH-, and metyrapone- stimulation indicate the greatest relative

Drawbacks in the use of 23-nor-deoxycholic acid standards.

23-Nor-deoxycholic acid is widely used as internal standard in gas-liquid chromatographic studies of bile acids. Two batches of this compound, submitted to conventional alkaline hydrolysis of bile acid conjugates, were found to be transformed into a product with chromatographic properties different from those of "authentic" 23-nor-deoxycholic acid. To identify this "new" product a comparison was made between chromatographic properties, mass spectra, and NMR spectra of 23-nor-deoxycholic acid before and after alkaline hydrolysis. The results indicate that the "new" compound is the true 23-nor-deoxycholic acid while the product present in the two batches examined is a monoacetate derivative.

Sugar Present in Tobacco Extracts

The presence of fructose, glucose, sucrose, maltose, and isomaltose in commercial tobacco products was identified and quantitated. Gas-liquid chromatographic studies showed that these five types of sugar were present in the water-soluble extracts of pouch and plug chewing tobacco, yet only fructose and glucose were found in extracts of snuff and unprocessed natural tobaccos. The amount of sucrose present in pouch chewing tobacco was twice that in plug chewing tobacco. No detectable amount of sucrose was found in snuff or unprocessed natural tobaccos. The content of maltose and isomaltose was much less than the content of fructose, glucose, or sucrose. All unprocessed natural tobacco leaves studied as controls contained low amounts of fructose and glucose, and no detectable amounts of sucrose, maltose, or isomaltose. The larger amounts of fructose and glucose, and the additional sucrose, maltose, and isomaltose present in pouch and plug chewing tobaccos are probably added during the manufacturing process.

Rapid Diagnosis of Anaerobic Empyema by Direct Gas-Liquid Chromatography of Pleural Fluid

Sixty samples of pleural fluid from 52 patients were subjected to direct gas-liquid chromatographic studies, and results were correlated with findings from microbiologic cultures. Fourteen patients had anaerobic empyema, 22 had aerobic infections, and 16 had sterile pleural effusions. Multiple volatile fatty acids or succinic acid or both were found as markers of anaerobic infection in all but one instance. Aerobic infections and sterile pleural fluids were characterized by the absence of multiple volatile fatty acids or succinic acid. Infection with Bacteroides, when present, was characterized by a major product of succinic acid. One patient infected with Peptococcus magnus (which does not produce fatty acids or succinic acid) could not be diagnosed by gas-liquid chromatograms. Two patients without anaerobic bacteria in the pleural effusions but who had infections associated with Bacteroides fragilis outside the pleural space demonstrated succinic acid in the pleural fluid. With these exceptions, the presence of volatile fatty acids or succinic acid in pleural fluid was considered characteristic of anaerobic empyema. Direct gas-liquid chromatographic study of pleural fluids is, therefore, recommended as a routine procedure for rapid diagnosis of anaerobic empyema.

Gas–liquid chromatographic studies of thermodynamic interactions in ternary systems comprising dinonylphthalate + trinitrotoluene + volatile hydrocarbon

Gas–liquid chromatographic partition coefficients have been determined at 82°C for eleven hydrocarbons, aliphatic and aromatic, in the stationary phases di(3,5,5-trimethylhexyl)phthalate (DNP), and 2,4,6-trinitrotoluene (TNT), and in the mixed stationary phases. The Flory—Huggins model is used to derive a simple relation between partition coefficients in the mixed solvent phase and those in the pure solvents, and this relation gives an excellent fit for the aliphatic solutes with a consistent value of the DNP–TNT interaction parameter. The relation is less satisfactory for the results with the aromatic solutes and the model is modified to allow for the possible formation of charge transfer complexes between TNT and the aromatic solutes. A quantitative treatment is then shown to be possible only by using the approximations of solubility parameter theory.

Flameless Atomic Absorption (FAA) and Gas-Liquid Chromatographic Studies in Arsenic Bioanalysis

Flameless Atomic Absorption (FAA) and Gas-Liquid Chromatographic Studies in Arsenic Bioanalysis

Gas-liquid chromatographic studies of reactions and structural relationships of steroids : V. concurrent substitution in the pregnane side-chain and position 11

Qualitative and quantitative effects of classical reactions on steroids observed by gas-liquid chromatography (GLC) under standardized conditions, including the double internal standard technique, are reported. Simple procedures applicable to nanogram amounts of reactants are described. Reactions studied include the conversion of keto groups to hydroxyl groups by NaBH 4, and the removal of the pregnane side-chain with NaBiO 3. GLC chromatograms readily provide information on effects on functional groups at positions 3, 11, 17, 20, and 21 and the retention times of many steroids unavailable from commercial sources. GLC data analysis provides relationships between steroid structure and retention time from which methods for the computation of retention times and steroid identification are designed. The accuracy of these methods is demonstrated.

Gas-liquid chromatographic studies of reactions and structural relationships of steroids: IV. Substitution in the pregnane side-chain

Qualitative and quantitative effects of classical reactions on steroids observed by gas-liquid chromatography (GLC) under standardized conditions, including the double internal standard technique are reported. Simple procedures applicable to nanogram amounts of reactants are described. Reactions studied include the conversion of keto groups to hydroxyl groups by NaBH 4, and to dioxolone derivatives by 1,2-diethanol; 17α-hydroxylation of C20-ketosteroids; the conversion of hydroxyl groups to trimethylsilyl (TMS) ethers by hexamethyldisilazane; the hydrolysis of dioxolone and TMS derivatives by H +. Effects of the Wolff-Kishner reagents, and CrO 3 were also studied. GLC chromatograms of reaction mixtures of single- and multistep reactions readily provide information on effects on functional groups at positions 3, 17, 20, and 21 in the pregnane series, and the retention times of many steroids unavailable from commercial and other sources. GLC data analysis provides relationships between steroid structure and retention time from which methods for the computation of retention times and for steroid identification are designed. The accuracy of the computation methods is demonstrated.

Gas—liquid chromatographic studies of reactions and structural relationships of steroids : Part III. 11α-hydroxysteroids of the androstane and pregnane series

Qualitative and quantitative effects of classical reactions on steroids observed by gas—liquid chromatography (GLC) under standardized conditions, including the double internal-standard technique, are reported. Simple procedures applicable to nanogram amounts of reactants which afford excellent yields of the major products are described. Reactions studied include the Wolff—Kishner removal of keto groups, their conversion into hydroxyl groups with sodium—ethanol or sodium borohydride and into dioxolone derivatives with ethylene glycol; the conversion of hydroxyl into keto groups with chromium trioxide and to trimethylsilyl (TMS) ethers by hexamethyldisilazane; the hydrolysis of dioxolone and TMS derivatives by H +. Gas—liquid chromatograms of reaction mixtures of single- and multistep reactions readily provide information on the effects on the 11α-hydroxy and other functional groups at positions 3 and 17 (androstane series) and positions 3 and 20 (pregnane series), and the retention times of many steroids unavailable from commercial or other sources. GLC data analysis provides relationships between steroid structure and retention time from which methods for the computation of retention times and for steroid identification are designed. The accuracy of the calculation methods is demonstrated.