Capillary Gas-liquid Chromatography Research Articles

Polyunsaturated fatty acids in plasma lipids of obese children with and without metabolic cardiovascular syndrome.

Previously we reported significantly higher values of gamma-linolenic acid (GLA, 18:3n-6), dihomo-gamma-linolenic acid (DHGLA, 20:3n-6), and arachidonic acid (20:4n-6) in plasma lipid classes in obese children than in nonobese controls. In the present study, fatty acid composition of plasma phospholipids (PL) and sterol esters (STE) was determined by high-resolution capillary gas-liquid chromatography in obese children with and without metabolic cardiovascular syndrome [MCS: defined as simultaneous presence of (i) dyslipidemia, (ii) hyperinsulinemia, (iii) hypertension, and.(iv) impaired glucose tolerance] and in nonobese controls. Fatty acid composition of PL and STE lipids did not differ between obese children without MCS and controls. Obese children with MCS exhibited significantly lower linoleic acid (LA, 18:2n-6) values in PL (17.43 [2.36], % wt/wt, median [range from the first to the third quartile]) than obese children without MCS (19.14 [3.49]) and controls (20.28 13.80]). In contrast, PL GLA values were significantly higher in obese children with (0.13 [0.08]) than in those without MCS (0.08 [0.04]), whereas STE GLA values were higher in obese children with MCS (1.04 [0.72]) than in controls (0.62 [0.48]). DHGLA values in PL were significantly higher in obese children with MCS (4.06 [0.74]) than in controls (2.69 [1.60]). The GLA/LA ratio was significantly higher, whereas the AA/DHGLA ratio was significantly lower in obese children with MCS than in obese children without MCS and in controls. In this study, LA metabolism was affected only in obese children with but not in those without MCS. In obese children with MCS, delta6-desaturase activity appeared to be stimulated, whereas delta5-desaturase activity appeared to be inhibited. Disturbances in LA metabolism may represent an additional health hazard within the multifaceted clinical picture of MCS.

Structural Analysis of Bio-Oils from Fixed-Bed Pyrolysis of Euphorbia rigida and Sunflower Pressed Bagasse

Fixed-bed tars of Euphorbia rigida and sunflower pressed bagasse have been investigated for their structures. These tars were fractionated into pentane-soluble and -insoluble compounds (asphaltenes). Pentane soluble were then solvent fractionated into pentane, toluene, ether, and methanol subfractions by fractionated column chromatography. The aliphatic and low-molecular-weight aromatic subfractions of the bio-oils were then analyzed by capillary column gas-liquid chromatography and GC/MS. Further structural analysis of bio-oils and aromatic and polar subfractions were conducted to FTIR and 1HNMR spectra.

Mercury species in the liver of ringed seals

Four types of mercury species, namely, methylmercury, organic mercury other than methylmercury, inorganic mercury, and insoluble mercury, deemed to be mercuric selenide (HgSe), were found in the liver of 45 ringed seals from the Canadian Arctic. On average, methylmercury, at 2%, made up the smallest fraction of the total mercury in the liver of these animals. Of the total mercury concentration in seal liver, 53% was insoluble mercury, estimated to be largely mercuric selenide. Other workers have found this compound to be present in mammalian liver and identified it to be HgSe. Organic mercury other than methylmercury made up 4%, and inorganic mercury 42% of the total mercury in the liver. The sum of the independently determined mercury species agreed well with the total mercury concentration in the liver. Species other than mercuric selenide are known to be toxic. Mercuric selenide, considered to be a stable end product of the demethylation process of methylmercury, although not readily eliminated from the liver, is inert and apparently non-toxic. Only approximately half of the total mercury in the liver was potentially toxic mercury. All four mercury species were positively correlated with the age of animals, the regression slope on age being 20 times larger for insoluble Hg (HgSe) than for methylmercury. A number of reported observations, such as the long half-life of Hg in liver (?≥10 years), the dependence of Hg on age, and the often-observed one-to-one relationship between Hg and Se (on a molar basis), are readily explained by the temporal accumulation of HgSe in the liver. In the future, a more accurate assessment of the health risk to animals and humans from the consumption of contaminated animal tissues will be possible, by measuring all mercury species rather than just total mercury or methylmercury. Total mercury alone in the liver is an inadequate indicator of toxicity to animals. Methylmercury was analyzed by capillary gas-liquid chromatography with ECD detection, and the other species were operationally/experimentally defined using physical/chemical methods.

Determination of fatty acid composition and total trans fatty acids of Turkish biscuits by capillary gas-liquid chromatography

In this research, fatty acid composition and total trans fatty acid contents of six types of biscuit produced by four different Turkish companies were determined by capillary gas-liquid chromatography. Total fat contents of the biscuit samples ranged between 8.5% and 26.0%. The highest fat content was determined in sesame biscuits (average 24.4%) and the lowest in petit beurre biscuits (average 13.5%). Total fat contents varied even for the same type of biscuit as a result of the use of different recipes by each company. The major fatty acids in the samples were C16 : 0, C18 : 0, trans C18 : 1, C18 : 1, trans C18 : 2 and C18 : 2. Depending on the biscuit type, total unsaturated fatty acid contents were between 52.1% and 72.8%. The ranges of total trans fatty acid contents in biscuit types were petit beurre 1.9–29.0%, sesame 15.0–23.1%, baby 3.0–30.5%, oat 17.6–22.4%, cocoa 1.5–22.9% and finger 1.0–24.7%. It is clear from the results that the percentage of trans fatty acids in the total fat content is significant because of the use of hydrogenated vegetable oils in biscuit production.

Use of equations for the description of experimental dependence of the height equivalent to a theoretical plate on carrier gas velocity in capillary gas–liquid chromatography

Optimal equation for fitting the experimental data on the height equivalent to a theoretical plate (HETP) versus carrier gas velocity in GLC was determined. The data obtained by authors and the literary data by other investigators were used for the comparative study of Van Deemter, Golay and the little known Golay–Guiochon equations. The Golay–Guiochon equation takes into account instrumental contribution and other sources of additional band broadening. Correlation coefficient R and Pirson’s criterion χ 2 were used as a criterion of the data correspondence to the equations. The Golay–Guiochon equation is the best for fitting of the experimental data in 71% considered examples, 19% experimental data may be fitted very precisely by the Van Deemter equation, the Golay equation is preferable for 7% experimental data only. Three percent experimental data may be fitted with the same precision by the Golay and the Van Deemter equations. The results obtained are of theoretical and practical interest. The Golay–Guiochon equation must be used more widely in analytical practice and physicochemical measurements.

Essential Fatty Acids and Their Long-Chain Polyunsaturated Metabolites in Maternal and Cord Plasma Triglycerides during Late Gestation

The fatty acid composition of plasma lipids was determined in 41 pairs of mothers and their term infants at time of birth (38–42 postmenstrual weeks) by high-resolution capillary gas-liquid chromatography. Linoleic and α-linolenic acids were found at smaller concentrations in cord than in maternal triglycerides, in contrast to strikingly higher proportions of their long-chain polyunsaturated metabolites (LC-PUFA), which indicates a preferential maternofetal transport for certain physiologically important LC-PUFA. While no significant gestational age-dependent changes occurred in maternal plasma triglycerides, the values for most of the fetal long-chain n–3 metabolites increased with the duration of gestation, possibly reflecting an increased transplacental fatty acid passage during late pregnancy or a maturation of desaturation in the fetal liver.

The fatty acid composition of human milk in northern Nigeria.

The authors previously reported that the milk of Yoruba women in southwestern Nigeria was deficient in alpha-linolenic acid and contained a high percentage (42%) of medium chain-length fatty acids (MCFA, C10-C14). In the present study, the authors used capillary gas-liquid chromatography to analyze the milk of Hausa women in the northern region of Nigeria. The milk of the Hausa women contained 27% MCFA, 10.6% linoleic acid, 0.41% alpha-linolenic acid, 0.52% arachidonic acid, and 0.32% docosahexaenoic acid. The proportion of alpha-linolenic acid in the serum phospholipids of a subset of exclusively breastfed infants (n = 15; mean age, 6.2 +/- 0.3 months) was below the limit of detection (< 0.03%). While the milk of women in northern Nigeria is adequate with regard to n-3 and n-6 fatty acids, to satisfy the requirements for alpha-linolenic acid, it may be necessary to supplement the infants of these women after the first 6 months of life.

Carotenoid oxidative degradation products inhibit Na+-K+-ATPase

This study investigates the biological significance of carotenoid oxidation products using inhibition of Na+-K+-ATPase activity as an index. β-Carotene was completely oxidized by hypochlorous acid and the oxidation products were analyzed by capillary gasliquid chromatography and high performance liquid chromatography. The Na+-K+-ATPase activity was assayed in the presence of these oxidized carotenoids and was rapidly and potently inhibited. This was demonstrated for a mixture of β-carotene oxidative breakdown products, β-Apo-10′-carotenal and retinal. Most of the β-carotene oxidation products were identified as aldehydic. The concentration of the oxidized carotenoid mixture that inhibited Na+-K+-ATPase activity by 50% (IC50) was equivalent to 10μM non-degraded β-carotene, whereas the IC50 for 4-hydroxy-2-nonenal, a major lipid peroxidation product, was 120 μM. Carotenoid oxidation products are more potent inhibitors of Na+-K+-ATPase than 4-hydroxy-2-nonenal. Enzyme activity was only partially restored with hydroxylamine and/or β-mercaptoethanol. Thus, in vitro binding of carotenoid oxidation products results in strong enzyme inhibition. These data indicate the potential toxicity of oxidative carotenoid metabolites and their activity on key enzyme regulators and signal modulators.

Etude chez une population d’Aquitaine de l’effet des acides gras trans alimentaires sur les lipides plasmatiques et le profil des lipoprotéines

The objective of this study was to determine the effect of dietary trans fatty acids (TFA) on the risk of coronary heart disease (CHD) development, in 90 pregnant and 97 non-pregnant women, who were recruited between 1996 and 1999, in the South-West of France. The contents of TFA in total lipids, cholesteryl esters (CE) and total phospholipids (TPL) of the women’s plasma, were determined using a combination of thin layer chromatography and capillary gas-liquid chromatography. Results indicate that the mean content of total TFA in plasma total lipids, expressed as proportion of all fatty acids, was 0.7%, with trans 18:1 being the most prevalent isomers (67%), followed by trans 18:2 (25%) and trans 16:1 (8%). Trans 18:3 isomers were undetectable. In TPL, the TFA accounted for 0.7% of total fatty acids, whereas in CE, the mean TFA level was twice (0.3%) as lower than in TPL. Moreover, these TFA were mainly represented by trans 18:1 isomers in TPL, and by trans 18:2 isomers in CE. Furthermore, there was no evidence of significant correlations between concentrations of low-density-lipoprotein (LDL) or high-density-lipoprotein (HDL) cholesterol and the TFA percentage in either adipose tissue or plasma. Overall, based on these results, it appears that the TFA intake level of French population does not induce an increase of CHD risk.

Influence of oral dehydroepiandrosterone (DHEA) on urinary steroid metabolites in males and females

Oral dehydroepiandrosterone (DHEA) replacement therapy may have a multitude of potential beneficial effects and exerts its action mainly via peripheral bioconversion to androgens (and estrogens). A daily dose of 50-mg DHEA has been shown by us and others to restore low endogenous serum DHEA concentrations to normal youthful levels followed by an increase in circulating androgens and estrogens. As the hepatic first-pass effect may lead to a non physiological metabolism of DHEA after oral ingestion we studied the influence of two single DHEA doses (50 and 100 mg) on the excretion of steroid metabolites in 14 elderly males [age 58.8 ± 5.1 years (mean ± SEM)] with endogenous DHEAS levels <1500 ng/ml and in 9 healthy females (age 23.3 ± 4.1 years) with transient suppression of endogenous DHEA secretion induced by dexamethasone (dex) pretreatment (4 × 0.5 mg/day/4 days). Urinary steroid profiles in the elderly males were compared to the steroid patterns found in 15 healthy young men (age 28.9 ± 5.1 years). In the females the results were compared to their individual baseline excretion without dex pretreatment. Urinary steroid determinations were carried out by semiautomatic capillary gas-liquid chromatography. In both genders DHEA administration induced significant increases in urinary DHEA (females: baseline vs. 50 mg vs. 100 mg: 361 ± 131 vs. 510 ± 264 vs. 1541 ± 587 μg/day; males: placebo vs. 50 mg vs. 100 mg: 434 ± 154 vs. 1174 ± 309 vs. 4751 ± 1059 μg/day) as well as in the major DHEA metabolites androsterone (A) and etiocholanolone (Et). Fifty mg DHEA led to an excretion of DHEA and its metabolites only slightly above baseline levels found in young females and in young men, respectively, whereas 100 mg induced clearly supraphysiological values. After 50 mg DHEA the ratios of urinary DHEA metabolites (A/DHEA, Et/DHEA) were not significantly different between elderly males vs. young male volunteers and young healthy females versus their individual baseline levels. In conclusion, an oral dose of 30 to 50 mg DHEA restores a physiological urinary steroid profile in subjects with DHEA deficiency without evidence for a relevant hepatic first-pass effect on urinary metabolites.

Precise quantitative determination of phytosterols, stanols, and cholesterol metabolites in human serum by capillary gas–liquid chromatography

Total lipid extraction, solid-phase extraction, saponification, derivatization to trimethylsilyl ether derivatives, then capillary gas–liquid chromatography were used for quantitative analysis of sitosterol, campesterol, stigmasterol, sitostanol, campestanol, lathosterol, desmosterol, and lanosterol in human serum. Details of quality control integral to the accuracy and precision of analyses are included. The method limits of detection and quantitation, respectively, ranged from 0.05 μg/ml and 0.2 μg/ml for sitostanol to 0.4 μg/ml and 1.2 μg/ml for campesterol and campestanol. Analytes were measured at concentrations of 120 ng/ml to 6 μg/ml with standard deviations of 0.02 to 0.12 μg/ml for 55 analyses of a control serum sample conducted over a 2-month period.

Levels of Selected Polychlorinated Biphenyl Congeners in Total Diet Samples from Aragón, Spain

Six congeners of polychlorinated biphenyls (PCB 28, 52, 101, 138, 153, and 180) were investigated in 281 samples of different meals of the average diet consumed in Aragon, northeast Spain. PCB residues were extracted with organic solvents according to the techniques recommended by the U.S. Food and Drug Administration and the Netherlands' Ministry of Welfare, Health, and Cultural Affairs; the residues were cleaned up by gel permeation chromatography. Quantitation of analytes was carried out by capillary gas–liquid chromatography using electron capture detector. The identity of the peaks was confirmed by mass spectrometry. PCB residues were found only in fish meals (50% positive samples) with a mean level of 96.3 ng/g on a lipid basis. Congeners detected in fish meals were 138, 153, and 180, with mean values of 117.0, 122.3, and 36.2 ng/g on a lipid basis, respectively.

Content of lipid nutrients in the milk of Fulani women.

Little is known about the nutrition of the infants of the Fulani, migratory nomads of the western Sahel of Africa. Milk was collected from 18 Fulani women 10 to 30 days postpartum and the fatty acid compositions of the triacylglycerol and phospholipid fractions were determined by capillary gas-liquid chromatography. De novo fatty acids (10:0-14:0) comprised 36.3 +/- 12.7% of fatty acids of the triacylglycerols. Compared to the milk of various populations worldwide, the milk of the Fulani women contained adequate proportions of alpha-linolenic acid (0.50 +/- 0.16%) and arachidonic acid (0.42 +/- 0.22%), but relatively low amounts of linoleic acid (9.95 +/- 2.13%) and docosahexaenoic acid (DHA) (0.15 +/- 0.08%). In addition, the milk of the Fulani women contained adequate concentrations of beta-carotene (1.58 +/- 0.69 micrograms/dl) and vitamin A (42.7 +/- 40.3 micrograms/dl), but very low levels of vitamin E (0.11 +/- 0.10 mg/dl). These data indicate that exclusively breasted infants of Fulani women were receiving relatively low amounts of critical fatty acids and vitamin E.

Occurrence of gamma-linolenic acid in compositae: a study of Youngia tenuicaulis seed oil.

Seeds of Youngia tenuicaulis and other species from the plant family Compositae (Asteraceae) were studied for their oil content and fatty acid composition. The seed oil of Y. tenuicaulis growing in Mongolia was found to contain 5.6% gamma-linolenic acid (18:3delta6cis,9cis,12cis) in addition to common fatty acids. The oil was analyzed using chromatographic [capillary gas-liquid chromatography (GLC), thin-layer chromatography] and spectroscopic (infrared, gas chromatography-mass spectrometry) techniques. Seed oil fatty acids of Saussurea amara (containing gamma-linolenic acid) and of Arctium minus (containing 18:3delta3trans,9cis,12cis), as well as delta5cis- and delta5trans-18:3 were used as GLC reference substances. The evolution in this plant family of a large number of different 18:3 acids as well as the corresponding evolution of unusual desaturases should be investigated. On the other hand, the delta6cis-desaturase required for the biosynthesis of gamma-linolenic acid may have evolved independently several times in unrelated families of the plant kingdom.

FATTY ACID COMPOSITION OF COLOSTRUM AND MATURE HUMAN MILK IN HUNGARY

14 Fatty acid (FA) composition of human milk (HM) may differ considerably between populations. There were no up-to-date data on FA composition of HM in Hungary. Subjects and methods: FA composition of colostrum (n = 18, one hind milk sample on day 5 post partum) and mature HM [n = 15, pooled 24-h collection at median age of 4 (range: 1 to 14) months repeated twice with 2 weeks interval] samples was analysed with high-resolution capillary gas liquid chromatography. Fat contents were measured gravimetrically. Results: Contributions of linoleic (C18:2ω-6) and α-linolenic (C18:3ω-3) acids were significantly lower, whereas those of arachidonic (C20:4ω-6) and docosahexaenoic (C22:6ω-3) acids were significantly higher in colostrum than in mature HM (table). Neither fat contents [4.7 (0.9) and 4.8 (1.0) g/L, median (IQR)] nor FA compositions (table) differed between 24-h pooled mature HM samples obtained with two weeks interval. While C18:2ω-6, C20:4ω-6, and C18:3ω-3 values were similar to those reported for other populations, the contribution of C22:6ω-3 to FA composition of Hungarian mature HM samples was considerably lower than the values generally considered as characteristic to mature HM (Koletzko et al., J Pediatr 120: S62, 1992 ). In colostrum, significant and positive correlations were found between C18:2ω-6 and C20:4ω-6 (r = 0.71, P = 0.001), between C18:3ω-3 and C22:6ω-3 (r = 0.59, P = 0.01), and between C20:4ω-6 and C22:6ω-3 (r = 0.74, P < 0.001). No such correlations were seen in mature HM (-0.20 < r < 0.39, 0.18 < P < 0.89).Table: Fatty acid composition of colostrum (n=18) and 24-h pooled mature human milk measured twice with 2 weeks interval in the same women (n=15) [% wt/wt, median (IQR),a,b = P < 0.01,c,d = P < 0.001]Conclusion: Contribution of docosahexaenoic acid to the fatty acid composition of mature human milk is unexpectedly low in Hungary.

An optimized method for fatty acid analysis, including quantification of trans fatty acids, in human adipose tissue by gas-liquid chromatography

Considering the need for a quick direct method for measurement of the fatty acid composition including trans isomers of human adipose tissue we have developed a procedure using gas-liquid chromatography (GLC) alone, which is thus suitable for validation of fatty acid status in epidemiological studies. Fatty acids ranging in carbon number from 12 to 22 and with 0-6 double bonds were resolved and identified by capillary column GLC with a temperature program starting at 150°C. Following injection, the oven temperature was increased at a rate of 3°C/min to 200°C, then held constant for 25 min, and finally raised at 25°C/min to 225°C. The trans and cis

Methods for the determination of organochlorine pesticide residues in human serum

The effectiveness of solid-phase extraction with Florisil for the determination of 12 organochlorine pesticide residues from human serum was examined. Recoveries greater than 84% and coefficients of variation better than 19% were obtained. Others methods, such as column partition and matrix solid-phase dispersion, were compared. The better method provides quantification limits ranging from 1.08 μg/l for γ-HCH and 37.5 μg/l for p, p′-DDT when capillary gas–liquid chromatography with electron-capture detection is used for the final determination.

Analysis of sterol content and composition in fats and oils by capillary-gas liquid chromatography using an internal standard. Comments on the German sterol method

Analysis of sterol content and composition in fats and oils by capillary-gas liquid chromatography using an internal standard. Comments on the German sterol method

Histological and Chemical Characterization of Myrsine laetevirens Seed

Histological and chemical features in seeds of Myrsine laetevirens are described. Seed is endospermous and the endosperm consists of several layers of thick cell walls that store mainly xyloglucans. Next to the embryo, the endosperm cell walls are rich in pectins. In the endosperm, proteins are stored in typical protein bodies. In the embryo, vacuoles with small deposits of protein inside were distinguished. Globoids, found in the protein bodies of the endosperm, are absent in the embryo tissues. Energy-dispersive x-ray analysis of globoid revealed P, Mg, K, and Ca as the main nutrient minerals. Lipid vesicles are present in embryo and endosperm; in the embryo they are found mainly along the periphery of the plasmalemma. Determination of neutral sugars was performed after acid hydrolysis. Sugars were identified by high-performance anion exchange chromatography (Dionex). Arabinose, xylose, glucose, and galactose are the main monosaccharides, but the ratio differs in endosperm and embryo tissues. Uronic acids were determined by a colorimetric reaction. Analysis of fatty acids by capillary gas-liquid chromatography revealed the presence of C16:0, C18:0, C18:1, and C:18:2 fatty acids in embryo and endosperm. In the latter, traces of C12:0 also were detected. Soluble proteins were analyzed by polyacrylamide gel electrophoresis, which showed a different profile in both tissues. Few bands are glycosylated. This investigation was undertaken in order to initiate studies of the seed in the genus Myrsine. Similar studies in other genera of Myrsinaceae have not been reported, precluding a taxonomical comparison.

Fatty acid composition of lipid classes in maternal and cord plasma at birth.

The fatty acid composition of plasma phospholipids, triglycerides, cholesterol esters and nonesterified fatty acids was determined by high-resolution capillary gas-liquid chromatography in 41 pairs of mothers and their term infants at time of birth. The total free fatty acid content in maternal and cord plasma was positively correlated, possibly reflecting a passive, gradient dependent transplacental passage of nonesterified fatty acids. Higher percentage values of several saturated and monounsaturated fatty acids in cord than in maternal plasma phospholipids, triglycerides and nonesterified fatty acids may have resulted from an active fetal fatty acid synthesis. Trans fatty acids were found in every lipid class at similar or slightly lower percentages in neonatal as in maternal plasma, thus confirming their placental passage. Long-chain n-6 and n-3 polyunsaturated fatty acids are preferentially incorporated into phospholipids and sterolesters of both maternal and cord plasma. Linoleic and alpha-linolenic acids were found in smaller portions in cord than in maternal fatty acids, in contrast to strikingly higher proportions of their long-chain polyunsaturated metabolites, which may indicate a discriminating placental transport for certain physiologically important long-chain polyunsaturated fatty acids. The fetus appears to obtain fatty acids from a combination of de novo synthesis, a passive gradient dependent transplacental passage of nonesterified fatty acids and a selective materno-fetal placental transport for certain fatty acids, such as physiologically important long-chain polyunsaturated fatty acids.