High Temperature Capillary Gas Chromatography Research Articles

Fatty Acid Composition of Seed Oil from <i>Fremontodendron californicum</i>

The fatty acid composition of the low water-use shrub Fremontodendron californicum was examined by high temperature capillary gas chromatography. The ground seeds were extracted by supercritical fluid extraction (SFE) to obtain the oil (25.6% w/w) and for subsequent determination of the fatty acid composition. There are five fatty acids present at 1.0% or greater with linoleic 71% of the total. Oleic, palmitic, stearic, vaccenic plus traces of palmitoleic and linolenic comprise the remainder. The fatty acid methyl ester composition would make the oil suitable for biodiesel production.

Authentication of beeswax (Apis mellifera) by high-temperature gas chromatography and chemometric analysis

Chemical characterization and authentication of beeswax of Apis mellifera was performed by high temperature capillary gas chromatography coupled to electron impact mass spectrometry or to flame ionisation detection and chemometric analysis. Many major components (>50) of beeswax, odd and even hydrocarbons, oleofin, palmitate, oleate and hydroxypalmitate monoesters were detected, and for the first time palmitate and oleate monoesters esterified with 1-octadecanol and 1-eicosanol are reported to be present in beeswax. Unsupervised pattern recognition procedures, cluster analysis and principal component analysis, were used to find data patterns and successfully differentiate authentic and paraffin adulterated beeswax based on the chemical profile obtained. Independent assessment of beeswax quality and performance of the unsupervised classification methods were performed using classical analytical parameters. The discrimination power of the chemometric unsupervised methods for detection of paraffin adulterated beeswax was superior to the discriminating power of classical analytical parameters. Using linear discriminant analysis, classification rules for authentic and paraffin adulterated beeswax samples were developed. The model was validated by leave-one-out cross validation and showed good recognition and prediction abilities, 100% and 99%, respectively.

The separation of triacylglycerols using unpolar and medium polar capillary columns

Commercial by supplied triacylglycerols and synthesized triacylglycerols were used in this project. Analysed triacylglycerols with the range of carbon number (CN) 24–54 consisted of saturated and unsaturated fatty acids. Two capillary columns were used in the analyses of triacylglycerols, namely non-polar (Optima<sup>®</sup>-1-TG) and medium polar (Optima<sup>®</sup>-17-TG) types. In this study the effectiveness of separation (A) of triacylglycerols with different carbon number values, (B) of triacylglycerols with different unsaturation degree, (C) of positional isomers were determined and further possibilities to separate another lipid compounds were analysed. The column Optima<sup>®</sup>-17-TG separates TAG according to the degree of unsaturation while the column Optima<sup>®</sup>-1-TG separates saturated and unsaturated TAG. High temperature capillary gas chromatography was used to determine changes in triacylglycerol composition during the transesterification of structured fats.

Determination of Oligofructose, a Soluble Dietary Fiber, by High-Temperature Capillary Gas Chromatography

A high-temperature capillary gas chromatographic method was developed for the quantitative determination of oligofructose in foods and food products. Sample preparation involves oxymation and silylation of the extracted sugars. The oximetrimethylsilyl derivatives are analyzed on an apolar capillary column, with detection by flame ionization. The method is accurate, with recovery of spiked samples at >96%. Repeatability was excellent; RSD values of 1.1% were obtained. Other common oligosaccharides, such as malto-, isomalto-, and galactooligosaccharides, and levan do not interfere, making the method specific and reliable.

Quantitative analysis of triterpenes friedelan-3-?-ol and friedelin in Maytenus aquifolium by high-resolution gas chromatography and high- temperature capillary gas chromatography

The quantitative analysis of the pentacyclic triterpenes friedelan-3-β-ol and friedelin by high-temperature capillary gas chromatography (HT-CGC) and high-resolution gas chromatography (HRGC) is described. These compounds are markers of Maytenus aquifolium and M. ilicifolium (Celastraceae), plants which show anti-ulcer activity and which are used medicinally in Brazil under the name “espinheira santa”. HT-CGC was more efficient than conventional HRGC for the quantitative evaluation of triterpenes in the hexane extracts of leaves of M. aquifolium owing to the reduced retention times attainable without loss of resolution. The flame ionisation detector response and detection limits for both triterpenes using HRGC and HT-CGC were also established. Copyright © 2000 John Wiley & Sons, Ltd.

Comparison of classical and alternative extraction methods for the quantitative extraction of fat from plain chocolate and the subsequent application to the detection of added foreign fats to plain chocolate formulations

Three methods were compared for the quantitative extraction of fat from plain chocolate and cocoa products ranging from simple intermediary products such as cocoa butter, cocoa masses or liquors to market purchased chocolate samples. The classical method of extraction using an acid digestion followed by Soxhlet extraction was compared to two potentially alternative methods: microwave extraction and supercritical fluid extraction (SFE). The extracted intact triacylglycerols were then analysed directly by high temperature capillary gas chromatography (HT-GC). The results of extractions were compared by plotting the percentage areas of the three major triacylglycerols present one vs. the other. The results showed that the microwave extraction technique gave similar results to the more time-consuming classical extraction method. SFE gave results with higher standard deviations and a tendency to lower yields taking the acid digestion–Soxhlet method as the reference method. The minimal variations due to the methods did not impact the detection of foreign fats added to chocolate. However, the quantification of the foreign fats was impaired when using the SFE method compared to the other techniques due to the larger variations of replicate analyses of intact triacylglycerol profiles.

Mass spectrometric analysis of ceramide composition in mono-, di-, tri-, and tetraglycosylceramides from mouse kidney: an experimental model for uropathogenic Escherichia coli.

Many bacteria have been shown to bind to the carbohydrate part of glycosphingolipids, but also the lipid moieties of receptor-active glycolipids are of importance. To investigate the chemistry of the ceramides of kidney glycolipids to which the uropathogenic Escherichia coli bind, different mass spectrometric techniques were utilized. First, a mixture of glycolipids isolated from man and mice kidney was separated by thin-layer chromatography (TLC) and scanned by direct desorption from the plate by fast atom bombardment mass spectrometry (TLC/FAB-MS). Second, the glycolipids were purified by preparative TLC and analyzed by negative-ion FAB-MS. After methylation, further analyses were made with positive-ion FAB-MS, positive-ion electron ionization (EI)-MS, high-temperature capillary gas chromatography (GC/EI-MS) and positive-ion matrix-assisted laser desorption/ionization (MALDI)-MS. The ceramide compositions of the four glycolipids were determined using all these MS techniques and the reliability of the different methods for this type of analyses is discussed. Comparison of the mouse kidney glycolipids with the corresponding glycolipids from human kidney showed the same degree of hydroxylation of ceramides among mono- and disaccharide glycolipids, but a significantly higher degree of hydroxylation among mouse kidney glycolipids with three and four sugar residues. This result might be of relevance for the binding of P-fimbriated E. coli to the urinary tract tissues.

Triglyceride characterization of different mexican cheeses by high temperature capillary gas chromatography (HT‐CGC)

Triglyceride characterization of different mexican cheeses by high temperature capillary gas chromatography (HT‐CGC)

Quantification of Generic Salatrim in Foods Containing Salatrim and Other Fats Having Medium- and Long-Chain Fatty Acids

The methodology used in the quantification of various Salatrim mixtures in foods manufactured in combination with coconut oil, cocoa butter, and common vegetable oils is described. Salatrim is an interesterification product of triacetin, tripropionin, tributyrin, and hydrogenated vegetable oils. Approximately 95% by weight of Salatrim components are triacylglycerols with acyl carbon number (ACN) less than 42. In order to evaluate the method to measure Salatrim at various concentrations in foods containing other fats with similar ACN, 12 chocolate-coated peanut butter cup samples were made with several types of Salatrim, coconut oil at different concentrations, and other common vegetable oils and analyzed. The extraction of the crude fat from the samples by supercritical fluid carbon dioxide without the alteration of the triacylglycerol structures, separation of Salatrim from other lipids, and quantification by high-temperature capillary gas chromatography (HTCGC) with a short SIM-DIST fused-silica capilla...

Simultaneous estimation of microbial phospholipid fatty acids and diether lipids by capillary gas chromatography

The simultaneous measurement ofspecific phospholipid ester-linked fatty acids (PLFA) and diether lipids was achieved using high temperature capillary gas chromatography (GC). A GC method was developed and used to simultaneously determine diether lipid and PLFA content in the same GC run. The key features of the method were a slow (1°C/min) temperature ramp through the fatty acid region of the chromatogram followed by a high temperature ramp where the diether lipid eluted. Using this method on both pure bacterial cultures and aquatic sediments, resolution was achieved of the diether lipid and the PLFA, including novel C 16 and C 18 monounsaturated fatty acids derived from methanotrophs.

Use of methoxy-terminated poly(diphenyl/1H, 1H, 2H, 2H-perfluorodecylmethyl) siloxane as stationary phase for high temperature capillary gas chromatography and its application in the analysis of beeswax

This article reports a new fluoroalkyl/phenyl-substituted medium polar stationary phase for high-temperature gas chromatography (HTGC). Coated on glass capillaries, the methoxy-terminated poly(diphenyl-1H, 1H, 2H, 2H-perfluorodecylmethyl)siloxane film is thermally stable up to 400°C. As a consequence, the introduction of a high content of fluorine into the polymer results in significantly lower retention values, shorter analysis time, an improved signal-to-noise ratio at high column temperatures, and, in the end, an extension of the application range for HTGC. The preparation of the stationary phase and the coating procedure on deactivated glass capillaries is described in detail. The performance of the new GC phase is demonstrated on two quality tests (Grob and extended Donike) and on the separation of beeswax, which is a complex mixture of naturally occurring compounds. © 1997 John Wiley & Sons, Inc. J Micro Sep8: 553–559, 1996

Use of methoxy‐terminated poly(diphenyl/1H, 1H, 2H, 2H‐perfluorodecylmethyl) siloxane as stationary phase for high temperature capillary gas chromatography and its application in the analysis of beeswax

Use of methoxy‐terminated poly(diphenyl/1H, 1H, 2H, 2H‐perfluorodecylmethyl) siloxane as stationary phase for high temperature capillary gas chromatography and its application in the analysis of beeswax

Characterization and identification of the mucilage extracted from orchid bulbs (Bletia campanulata) by high temperature capillary gas chromatography (HT‐CGC)

AbstractThe aim of this work was to develop an analytical method by High Temperature Capillary Gas Chromatography (HT‐CGC) to characterize and identify the presence of tzauhtli, orchid mucilage, in works of art. During the pre‐Hispanic and colonial period, tzauhtli was used as an adhesive for paper and feathers, as well as paint binder, and was one of the components of the paste used to model corn stalk sculptures. The mucilage was extracted with hot water from orchid bulbs (Bletia campanulata) and lyophilized. The free sugars from the mucilage were analyzed by CGC after derivatization. The polysaccharide of the mucilage was characterized after its partial acid hydrolysis by HT‐CGC analysis of the oligosaccharides obtained. The proposed chromatographic method allows the identification of different mucilages in works of art. This contribution is the first report of the oligosaccharides from the hydrolysis of the mucilage extracted from orchid bulbs (Bletia campanulata).

Quantification of Generic SALATRIM Material in Foods by the Combination of Nontraditional Crude Fat Extraction and Short Nonpolar Column High-Temperature Capillary Gas Chromatography

This publication describes the methodology used in the quantification of generic SALATRIM in foods. SALATRIM is a family of structured triacylglycerols developed by the Nabisco Foods Group. It is an interesterification product of triacetin, tripropionin, tributyrin, and hydrogenated vegetable oils. Approximately 95% by weight of the SALATRIM components are either triacylglycerol species with two short-chain fatty acids and one long-chain fatty acid or triacylglycerol species with two long-chain fatty acids and one short-chain fatty acid. To develop a method to quantify generic SALATRIM material in foods, 11 food items (baked goods, confectionery products, and ice cream product) made with several SALATRIM materials at different concentrations, common vegetable oil, dairy fat, and cocoa butter as their main fat sources were evaluated. This publication reports on the extraction of crude fat from the food products by supercritical fluid carbon dioxide or 2-propanol-hexane column extraction method (WCR method) without altering their intact triacylglycerol structures and on the separation of SALATRIM from other lipid sources and quantification by high-temperature capillary gas chromatography with a short SIM-DIST fused silica capillary column GC analysis.

High temperature capillary GC analysis of phytopreparations of “espinheira santa” (Maytenus ilicifolia M. andMaytenus aquifolium M. — Celastraceae), a Brazilian antiulcer plant

We report a method for the analysis of triterpenes in aqueous alcoholic extracts ofM. ilicifolia orM. aquifolium leaves, using high temperature capillary gas chromatography in polar columns (OV-17-OH). These species are popularly known in Brazil as “espinheira santa” and have proven antiulcer properties. The method consists of the pre-concentration of the triterpenes from the aqueous alcoholic extract, followed by GC analysis, which permits the determination of the presence of friedelan-3-ol and friedelin. Direct comparison with several triterpenol standards that are usually found in falsified “espinheira santa” samples but are absent in the authentic drug, showed that GC analysis clearly allows detection of the presence of friedelan-3-ol and friedelin and, therefore, permits distinguishing between authentic and false “espinheira santa” aqueous alcoholic extracts.

Chemotaxonomic characterization of yeast cells.

Yeast species are analyzed on the basis of their lipid composition to evaluate if chemotaxonomic classification of different species is feasible. The cell walls of samples of Baker's and Brewer's yeast are disrupted by smashing the cells with glass beads at low temperatures. The liberated lipids are extracted with chloroform-methanol. Fractionation of the extract into simple lipids and complex lipids (phospholipids) is performed by column chromatography on silica gel. Elution with methanol produces the simple lipids fraction, whereas elution with methanol-chloroform-ammonium hydroxide produces the phospholipid fraction. The latter fraction is analyzed by high-performance liquid chromatography with light-scattering detection. High-temperature capillary gas chromatography of the simple lipids fraction permits the separation of waxes, sterols, squalene, sterol esters, free fatty acids, monoglycerides, diglycerides, and triglycerides.

Quantification of the C30+ fraction of North sea gas condensates by high temperature capillary gas chromatography

Good reproducibility and quantitative analysis of high molecular mass n-alkanes by high temperature capillary gas chromatography (HTCGC) is attainable. For the authentic n-alkanes, the method described in this paper gave for C20–C60, an sr of under 5% for manual injection, a linear response factor and a linear calibration over the concentrations used. When applied to the analysis of two waxy North Sea gas condensates, n-alkanes with carbon numbers extending above C80 were observed. This is a surprising result because condensates are generally low molecular mass fluids similar to gasoline. Good quantitative agreement was observed between HTCGC and conventional gas chromatography for carbon fractions less than C30 but HTCGC was able to extend the quantitative analysis to carbon numbers of at least C65.

Rapid screening of rolling mill oils using high-temperature capillary gas chromatography

The application of gas chromatography to rapid screening of rolling mill oils is investigated. A specially manufactured, high-temperature glass capillary column is used to separate typical rolling oil analytes such as fatty acids, mono-, di- and triglycerides, synthetic esters and mineral oil in one analysis. The column has a long life and meets the specifications set by ASTM D2887 for simulated distillation of mineral oils. Reliable and unique chromatograms are obtained to fingerprint a number of rolling mill oils. Information gathered can be correlated to the chemical composition and physical properties of commercial oils. A standard gas chromatograph, equipped with a split/splitless injector, gives sufficient reproducibility to detect significant changes in the composition of oils. The method is under evaluation for routine screening of batches of oils before release to the rolling mills.

Separation of novolac resin oligomers and related industrial materials by high temperature capillary gas chromatography

Separation of novolac resin oligomers and related industrial materials by high temperature capillary gas chromatography

The Determination of The Homologous Purity of Higher Normal Alkanes up to Dohectane with Capillary Gas Chromatography

The applicability of high-temperature capillary gas chromatography was tested for higher members of normal alkanes up to dohectane. The samples used were synthesized and showed a high state of purity. The linear relationships were proved between the logarithm of the retention time and the number of carbon atoms in the molecule, n, for the chromatography at an isothermal operation. It was possible to detect the difference in n by one for octacontane samples. The homologous impurity was proved to be quantitatively determined by the chromatography under an isothermal operation or under a programmed-temperature operation for mixtures of a limited range of n. The latter mode operation was desirable to detect higher components as sharp peaks. Even for dohectane the high-temperature capillary gas chromatography could be applied for the purpose of purity determination.