Capillary GLC Research Articles

Analysis of the fatty acid composition of erythrocyte phospholipids by a base catalysed transesterification method — prevention of formation of dimethylacetals

A sensitive method for the analysis of the fatty acid composition of erythrocyte phospholipids with capillary column GLC is described. Under the assay conditions (base catalysed transesterification with sodium methoxide), only the fatty acids of the phospholipids are converted to their methylesters. The alkenyl ether chains of the plasmalogens are not transmethylated. This eliminates the need for thin layer chromatography for the separation of dimethylacetals and esterified fatty acids. The method is suitable for the measurement of the fatty acid patterns of erythrocyte phospholipids in small blood samples.

Analysis of herbicide residues in sugar beet and sugar

A simple quantitative TLC method for the determination of the residues of herbicide inhibiting photosynthesis was compared with capillary GLC for the analysis of atrazine, chloridazone, lenacil, phenmedipham and desmedipham in sugar beet and sugar. No significant differences in the determination limit and precision of the two methods were found. Monitoring of herbicide residue levels in commercial sugar revealed low levels of atrazine (0.003 mg.kg-1 on average) in all the samples. This contamination level does not present a health hazard consumers.

H/D isotope effect in γ‐irradiated C10H22/C10D22 mixtures at 4 K deduced by studying dimeric products by gas chromatography

AbstractThe dimer products formed upon γ‐irradiation at 4 K of n‐decane‐d22 doped with 20% n‐decane‐h22 have been examined by means of capillary GLC coupled with mass spectrometry. Analysis of the results indicates that protiated alkyl radicals are selectively formed. This confirms the data obtained by radiolysis at 77 K. The selective abstraction of hydrogen from a C‐H bond on the solute molecules by the attack of D atoms which are formed by the radiolysis, occurs at 77 K. However, at 4 K, data from IWASAKI suggest an other explanation. The primary process is not selective but conversion of deuterated to protiated alkyl radicals takes place at 200 K.

Phenoxy ester herbicide identification and analysis

AbstractA test for the identity of specific phenoxy ester herbicides was required. Work with packed column and capillary GLC showed that the retention times could be used to identify major ester components. An esterification method with acetyl chloride produced a mean yield of 98% with a range of phenoxy acids and alcohols. This method could be used to produce standards for the specific quantitative analysis of esters in formulations.

Volatile constituents of Pteronia incana (compositae)

AbstractBy combination of capillary GLC and mass spectrometry, the essential oil of Pteronia incana (Compositae) from South Africa was analysed. It contains more than a hundred compounds, most of which were present as minor components; 56 components were identified.

Identification of sex pheromone of calendula plume mothPlatyptilia williamsii

The sex pheromone of the calendula plume moth,Platyptilia williamsii was identified as (Z)-11-hexadecenal (Z11-16∶Aid). Extracts of female sex pheromone glands contained several compounds when analyzed by capillary and packed-column GLC. However, airborne collections of volatiles from glands contained only one of these compounds, having the same retention time asZ11-16∶Ald. GC-MS and microozonolysis analyses of the natural product were consistent with those of syntheticZ11-16∶Ald. In a flight tunnel, males oriented upwind and touched sources ofZ11-16∶Ald and gland extract with equal frequency. Field tests of syntheticZ11-16∶Ald already have shown it to be a potent sex attractant for males of this species. This study further supports the hypothesis thatP. williamsii and a sympatric species,Platyptilia carduidactyla, are not reproductively isolated by chemical differences in the composition of the sex pheromone, but rather by temporal differences in sexual activities.

Investigation of the Alkaloid Pattern ofDatura innoxiaPlants by Capillary Gas-Liquid-Chromatography-Mass Spectrometry

The alkaloid composition of DATURA INNOXIA plants was analysed by quartz capillary GLC and GLC-MS. Significant differences were found in the alkaloid pattern of the respective plant organs even between different aerial parts. More than 30 alkaloids could be identified. Besides previously known substances, a further 18 tropine ester alkaloids as well as hygrine and tyramine were identified. Seventeen of these alkaloids have not been formerly found in the genus DATURA. Additionally, two hitherto unknown hygrine derivatives, presumably isomeric N-methylpyrrolidinyl-hygrines, were characterized.

Volatile components of Rhanterium epapposum oliv

AbstractThe composition of the essential oil of Rhanterium epapposum Oliv. (Compositae) growing in northeastern Iran has been investigated by TLC, liquid‐solid chromatography, capillary GLC, and GLC‐MS. The oil contained 107 volatile components of which 92% were terpenoids. The main constituents were α‐phellandrene, linalol, geraniol, bulnesol, and β‐phellandrene accounting for 55.6% of the oil. Non‐terpenoid aliphatic and aromatic structures have also been detected.

Changes in the Fatty Acid Content of Used Frying Fat Compared with Fresh Fat

AbstractIn 21 samples of used frying fat and the corresponding samples of fresh fat the fatty acid content was determined by capillary GLC on a CP Sil 88 column. The content of both saturated and unsaturated fatty acids as well as the content of total fatty acids are decreased by frying. Both the decrease in linoleic acid and the decrease in total fatty acids correlate well with % polar compounds as fat quality evaluation criteria. No isomers of cis,cis‐linoleic acid are formed during the frying process. The content of C18: 1 is increased during the frying process from about 0 to 8g/100g in average to 2.3g/100g, which means that also the frying process must be considered as a source to the human intake of trans fatty acids.

Cholesterol Oxides in Swedish Foods and Food Ingredients: Fresh Eggs and Dehydrated Egg Products

ABSTRACTCholesterol oxides were enriched from lipid extracts of fresh and dehydrated egg yolk products by chromatography on Lipidex and TEAP‐Lipidex. Appropriate fractions from TEAP‐Lipidex were analyzed by capillary GLC as their TMS derivatives. At the detection limit level, ca 0.2 ppm in total lipids, no cholesterol oxides could be detected in fresh egg yolk. Similarly, spray dried egg yolk powder contained only traces of cholesterol oxides when fresh or stored for 2 months at 4°C. Prolonged storage gave lipid extracts which contained variable levels (0.2–12 ppm) of known oxidation products, viz., cholest‐5‐ene‐3β, 7α‐diol, cholest‐5‐ene‐3β, 7β‐diol, 5,6α‐epoxy‐5α‐cholestan‐3β‐ol, 5,6 β‐epoxy‐5 β‐cholestan‐3β‐01, cholest‐5‐ene‐3β, 20α‐diol, 3 β‐hydroxycholest‐5‐en‐7‐one. Traces or small quantifiable amounts of cholest −5‐ene‐3β, 25‐diol and 5α‐cholestane‐3β, 5, 6β‐triol were observed in some samples at longer storage periods.

Diagnostic sensitivity of fasting and postprandial serum bile acids determined by different methods

The diagnostic sensitivities of serum bile acids determined by three different methods in the fasting and in the postprandial state were compared in 43 patients with cirrhosis of the liver. When a method with high analytical sensitivity (capillary gas-liquid chromatography, GLC, or radioimmunoassay, RIA) was used, the serum concentrations of bile acids exhibited similar diagnostic sensitivities in the fasting state (GLC, 98%; RIA, 93%) and in the postprandial state (GLC, 95%; RIA, 93%). By contrast, when an enzymatic method with limited analytical sensitivity was employed, the diagnostic sensitivity of fasting serum bile acids was lower (79%) than that of postprandial serum bile acids (93%). The measurement of individual serum bile acids by GLC did not add any further diagnostic information. The results of this study demonstrate that the diagnostic sensitivity of serum bile acids strongly depends on the analytical method used.

Gas—liquid chromatographic method for the determination of tolperisone in human plasma: pharmacokinetic and comparative bioavailability studies

A new capillary GLC method for the determination of tolperisone in human plasma was developed. Pharmacokinetic and comparative bioavailability studies were carried out after i.v. administration and after oral administration of two different preparations of tolperisone. After i.v. administration of the drug the elimination half-life was found to be 1.55 +/- 0.7 h (mean +/- S.D.), the apparent volume of distribution to be 5.1 +/- 1.0 l/kg (mean +/- S.D.) and total body clearance to be 140.8 +/- 33.8 l/h (mean +/- S.D.). The oral bioavailability was found to be 22.3 +/- 6.3% for Mydeton tablets and 16.7 +/- 8.9% for Mydocalm tablets. There was no significant difference between the bioavailability of two oral tablets.

Cyclic fatty esters: Synthesis, characterization, and lipolysis of isomeric triglycerides of 9-(6-propyl-3-cyclohexenyl)( Z)-8-nonenoic acid

Triglycerides of a model cyclic fatty acid (CFA) 9-(6-propyl-3-cyclohexenyl)-( Z)8-nonenoic acid (Ia) were synthesized for biological and toxicity evaluations. The monoacid triglyceride II (CyCyCy) was interesterified with triolein (OOO) to obtain mixtures of diacid triglycerides: III (OOCy), IV (OCyO), V (OCyCy), and VI (CyOCy). The interesterification mixtures were separated by preparative HPLC into two ‘critical pairs’ of isomeric triglycerides. Triglycerides III–VI were synthesized and a 13C-NMR method was developed to estimate ‘critical pairs’, CFA-triglycerides were characterized by IR, NMR, HPLC and capillary GLC, and their relative rates of hydrolysis by lipase were compared. Although tricyclin (II) was completely resistant to lipolysis, triglycerides III and VI hydrolyzed significantly slower than triolein, and the ‘critical pairs’ hydrolyzed as readily as triolein. Therefore, partial CFA-triglycerides formed in heat-abused fats can undergo lipolysis and likely be absorbed like normal dietary fats.

A Joule‐Thomson cooler for stationary‐phase or thermal focusing in capillary GLC

Journal of High Resolution ChromatographyVolume 9, Issue 5 p. 298-300 Short Communication A Joule-Thomson cooler for stationary-phase or thermal focusing in capillary GLC V. Pretorius, V. Pretorius Institute for Chromatography, University of Pretoria, Pretoria 0002, Republic of South AfricaSearch for more papers by this authorK. Lawson, K. Lawson Institute for Chromatography, University of Pretoria, Pretoria 0002, Republic of South AfricaSearch for more papers by this authorE. R. Rohwer, E. R. Rohwer Institute for Chromatography, University of Pretoria, Pretoria 0002, Republic of South AfricaSearch for more papers by this author V. Pretorius, V. Pretorius Institute for Chromatography, University of Pretoria, Pretoria 0002, Republic of South AfricaSearch for more papers by this authorK. Lawson, K. Lawson Institute for Chromatography, University of Pretoria, Pretoria 0002, Republic of South AfricaSearch for more papers by this authorE. R. Rohwer, E. R. Rohwer Institute for Chromatography, University of Pretoria, Pretoria 0002, Republic of South AfricaSearch for more papers by this author First published: May 1986 https://doi.org/10.1002/jhrc.1240090511Citations: 3AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinked InRedditWechat Citing Literature Volume9, Issue5May 1986Pages 298-300 RelatedInformation

Metabolic activation of olefins: Conversion of 1-octene to a putative reactive intermediate 1-octen-3-one: An alternative pathway to epoxidation

1. The enzymic activation of a model olefin oct-1-ene was studied in rat liver microsomal systems in vitro. 2. An active metabolite was trapped using N-acetylcysteine and identified by means of capillary GLC/ mass spectrometry and 360 MH z 1H NMR as S-3-oxo-octyl- N-acetylcysteine. A two step pathway for the formation of this adduct was proposed involving first the production of oct-1-en-3-ol by NADPH dependent mixed function oxidases and secondly a NADP or NAD linked oxidation, independent of cytochrome P-450, to yield the putative reactive intermediate oct-1-en-3-one. 3. Under physiological conditions, oct-1-en-3-one, prepared chemically, reacted non-enzymically with N-acetylcysteine with a t 1 2 of about 6 sec. 4. Enzymes catalysing the NADP-dependent oxidation of octen-3-ol were present in microsomal preparations from a number of organs apart from the liver, those from adrenal and intestinal epithelia showing the next highest levels of activity. Unlike the activation of octene, rates of hepatic activation of octen-3-ol were not induced by pretreatment of rats with phenobarbitone or 3-methylcholanthrene. 5. Using 1-octene as the substrate, comparisons were made of alternative routes of hepatic metabolism activation. Relative to the rate of formation of the 3-oxo intermediate trapped with N-acetylcysteine, epoxidation of octene and subsequent hydrolysis to octane-1,2-diol was over 40 times more rapid. The rate of formation of a presumptive oxirane precursor trapped with the haem of cytochrome P-450 as N-(2-hydroxyoctyl) protoporphyrin IX was about 17-fold lower.

Action of ozone on methyl octadec-9-enoate in polar solvents: A model for aqueous ozonization of organic compounds

Aqueous ozonization of methyl octadec-9-enoate resulted in aldehyde and carboxylic acid group formation at the fragmented CC bond. High ozone doses lead to increased oxidation of aldehyde to carboxylic acid groups. Methanolic ozonization produced dimethyl acetal groups in preference to aldehyde groups, and methylation of carboxylic acid groups was noted. Analysis of reaction products was performed by capillary GLC and GC-MS. Results were consistent with radical attack ( OH or OMe) for ozonization in polar solvents.

Brain lipids of giant panda and brown bear: Analysis of long-chain fatty acids of the glycosphingolipids by fused-silica capillary GLC

Glycosphingolipids were isolated from the brain of giant panda and brown bear, and their distribution and constituents were investigated in detail. The content and general profiles of lipid classes were similar in giant panda and bear brain, being typical of those of adult mammalian brain. Cerebroside fatty acid ester (ester cerebroside) was found in the cerebellum as well as cerebrum. A fused-silica capillary column coated with OV-101 was found to be efficient for GLC analysis of fatty acids prepared from brain glycosphingolipids. These fatty acids consisted of hydroxy and nonhydroxy components in a ratio of about 60:40 in cerebroside and 30:70 in sulfatide. Amide-linked fatty acids of ester cerebroside were richer in hydroxy components (70% of the total). The proportions of individual fatty acids of glycosphingolipids were almost identical in giant panda and brown bear, with 24:0, 24:1, 24 h:0, 24 h:1 and 18:0 being the major components. The distribution and constituents of gangliosides were essentially similar to those generally found in mammals: stearic acid accounted for almost 90% of the total, and the long-chain base consisted of sphingenine and icosasphingenine in a ratio of 65:35. Some discrepancies between a previous study on the giant panda "Chi-Chi" in London Zoo and the present study are discussed.

Unusual essential oils with aromatic properties—I. Volatile components of Stevia rebaudiana bertoni

AbstractBy combination of liquid‐solid chromatography, capillary GLC and mass spectrometry, the essential oil obtained by steam distillation from the dried leaves of Stevia rebaudiana Bertoni (Asteraceae) imported from Brazil, was analyzed. Caryophyllene oxide and spathulenol accounted for about 43% of the oil, which contained more than a hundred compounds, most of which were present only in traces; 54 components were identified.Also the essential oil obtained by steam distillation from fresh plants of Stevia, cultivated in the Botanical Garden of Turin University, was analyzed.

Quinolizidine Alkaloids as Nitrogen Source for Lupin Seedlings and Cell Cultures

Abstract The alkaloid patterns during germination and seedling development of Lupinus polyphyllus, L. angustifolius, L. albus, L. pubescens, Cytisus scoparius, Baptisia australis, Spartium junceum and Laburnum anagyroides were studied by capillary glc and EI-MS and CI-MS. The alkaloid contents were relatively high in the seeds and decreased by 20-100% during germination and the early developmental stages. The plants with fully developed leaves were able to synthesize new alkaloids. The decrease of alkaloid concentrations during germination was interpreted in terms of alkaloid turnover and use of the alkaloidal nitrogen for seedling development. The ability of plants to rely on the alkaloidal nitrogen as a nitrogen source could also be shown in lupin cell cultures which could survive and even grow on media which contained sparteine as the sole nitrogen source.

The di- and triesters of the lipids of steer and human meibomian glands.

Three groups of diesters have been isolated and identified in the lipids of steer meibomian glands. The first group, designated as alpha Type I, with the abbreviated formula FA-alpha OHFA-FAlc, consisted of alpha-hydroxy fatty acids esterified to fatty acids and fatty alcohols in the approximate molar ratio 1:1:1. The second group, designated as omega Type I-St, with the abbreviated formula FA-omega OHFA-St, consisted of omega-hydroxy fatty acids esterified to fatty acids and sterols in the approximate molar ratio 1:1:1. The third group, designated as alpha, omega Type II, with the abbreviated formula FA-alpha, omega diol-FA, consisted of alpha, omega-diols esterified to 2 moles of fatty acids. The sum of the different diesters comprised about 9% of total steer meibomian lipids. Capillary GLC of the fatty acids of alpha Type I diesters showed the fatty acids to be a family with a two-cluster profile, one at C12 to C20 and the other at C21 to C31, with anteiso chains predominating. Fatty acids from omega Type I-St and alpha, omega Type II diesters gave mainly a one-cluster profile in the short chain region with prominent anteiso and C18:1 peaks. Fatty alcohols of alpha Type I diesters were mainly long chain, C23 to C30, with anteiso chains predominating, while the alpha-hydroxy fatty acids were short chain C13 to C18 acids with C16 predominating. The sterols in diesters omega Type I-St were cholesterol (approximately 60%), delta 7 cholestenol (approximately 35%) and an unidentified compound (approximately 5%) with a GLC retention time slightly longer than delta 7 cholestenol on SE-30 phase. The omega-hydroxy fatty acids and alpha, omega-diols both were of exceedingly long chain lengths, C29-C38, and showed similar GLC profiles. Two types of triesters comprising approximately 1% of total steer meibomian lipids have been isolated but incompletely characterized. In terms of molar ratios, one group of triesters gave fatty acids:omega-hydroxy fatty acids:alpha-hydroxy fatty acids:sterols + fatty alcohols as approximately 1:1:1:1. The other contained fatty acids, alpha-hydroxy fatty acids and alpha, omega-diols in what appears to be a complex mixture of several triesters. Diesters omega Type I and alpha, omega Type II also were found in human meibum. Hitherto these two diesters have not been found in any animal tissue.