High Resolution Glass Capillary Columns Research Articles

Measurement and modeling of the concentrations of terpenes in coniferous forest air

In a coniferous forest area northeast of Oslo, Norway, air samples were collected by adsorption on activated carbon and analyzed by gas chromatography with a high resolution glass capillary column and flame ionization detection. During June and August 1980, seven terpenes were identified with a total concentration range of 8.8–70.7 ppbC (parts per billion, as carbon). α‐Pinene, terpinene, and p‐cymene occurred in the highest concentrations. A one‐dimensional vertical grid model of the atmospheric boundary layer with a detailed mechanism for inorganic and organic gas phase chemical turnover was applied to assess the vertical variability of the terpene concentrations as a function of the ozone concentration, the source strength of the terpenes, the time of the day, the upwind air composition, etc. The calculations showed that very little of the terpene emissions remained airborne after 4–8 hours, in contrast to the anthropogenic hydrocarbons. It was found that the anthropogenic fraction of the hydrocarbons may dominate in concentration, even though the natural part of the source is the larger one. Emission of 2000 μg(m2 h)−1 of terpenes was calculated to give ground level concentrations of total terpenes of up to about 25 ppbC, comparable to or less than the measured concentrations. Terpene emission at this rate was shown to suppress the hydroxyl concentration compared to a model case with zero terpene emissions, while the impact on ozone during daytime was negligible.

Characterization of hydrocarbon waxes by gas-liquid chromatography with a high-resolution glass capillary column

Sixteen hydrocarbon waxes of four different types were characterized by high-resolution glass capillary gas chromatography (GC) coupled with a direct vaporizer for solid samples. A furnace-type pyrolyser is used as the vaporizer. Components having very similar structures, such as branched-chain alkanes and the corresponding n-alkanes, were clearly separated using a high-resolution glass capillary column. The resulting GC data were correlated with various physical properties of the waxes, such as melting point, refractive index, degree of needle penetration and specific gravity. Thermogravimetric analysis and other thermal methods were also used to determine the molecular weight distributions and average molecular weights of the waxes.

Serum bile acid analysis.

Routine and research techniques are outlined for the analysis of bile acids in serum. The basis of these techniques is the use of liquid-solid extraction and liquid-gel chromatography coupled with the measurement of bile acids by gas chromatography using high resolution glass capillary columns and mass spectrometry which provides increased sensitivity compared with conventional methods of measurement. Problems associated with the isolation and purification of bile acids from serum are discussed and rapid and flexible methods for their metabolic profiling are described. The advantages and applicability of these procedures are illustrated with examples of profiles of bile acids in the serum from normal subjects, patients with liver disease and a patient with an ileal resection.

Detection of aliphatic hydrocarbons derived by recent “bio-conversion” from fossil fuel oil in North Sea waters

The higher boiling point range of saturated aliphatic hydrocarbon fractions extracted from North Sea water have been re-investigated in detail with improved high resolution glass capillary columns suitable for high temperature gas-chromatography. The resulting chromatograms reveal hydrocarbon patterns, most of which have the same common feature: a smooth distribution of the long-chain n-alkanes combined with a lack of the branched alkanes normally expected for fossil fuel oil. Instead, two homologous series of iso- and anteiso-alkanes could be detected. Since this finding is always associated with traces of present or past fossil fuel oil contamination of the upper water column, these environmental n-, iso and anteisoalkanes are considered to be recently ‘bio-converted’ from fossil fuel oil hydrocarbons. They form a third group beside recent biogenic and fossil petrogenic hydrocarbons in the marine environment. Oil pollution records of the marine environment will have to take into account this group of microbial hydrocarbons.

High resolution glass capillary columns for the gas chromatographic analysis of alditol acetates of neutral and amino sugars

AbstractThe development of improved high resolulation glass capillary columns for separating the alditol acetates of neutral and amino sugars is described. Different capillary column treatments were evaluated for their activity toward amino sugar derivatives and for their effect on the efficiency of the completed column. The simple two‐step procedure of leaching with aqueous hydrochloric acid and dynamic coating with SP‐2330 was found to produce efficient and inert columns.

Gas chromatography of aliphatic lactones on high-resolution glass capillary columns

Long wall-coated open-tubular glass columns coated with polar or non-polar partition liquids have been used for separation of mixtures of 30 aliphatic lactones. The method developed has been applied to analysis of an aroma fraction from the fruit of the date palm (Phoenix dactylifera) and 18 lactones have been identified in it.

High resolution glass capillary columns with chemically bonded stationary phases: application to the gas chromatographic analysis of sterols and steroids in biological extracts

AbstractA new approach has been developed for the preparation of highly stable glass capillary columns using irreversible bonding of polysiloxane polymers to the glass surface. The general procedure involves (a) synthesis of reactive linear polysiloxanes from variously (alkyl, aryl) substituted dichlorosilanes through homologous or heterologous polymerization under alcaline aqueous conditions, and (b) covalent condensation of the polymers to a properly prepared glass capillary surface at high temperature. The principle has been first applied to the successful preparation of apolar gas chromatographic systems (methylpolysiloxanes), then extended to the obtention of polar systems (methyl phenyl polysiloxanes). The flexibility of the approach is demonstrated by the possibility of obtaining stationary phases of various and controlled polarity (i.e., extent of phenyl substitution), tailor‐made to a given analytical problem. These gas Chromatographic systems appear to be remarkably stable both with time and temperature up to 300 C and compare favorably to existing systems for their high resolution properties. These columns have been satisfactorily used in the last years for the analysis of sterols and steroids of biological origin and most extensively in the study of urinary steroid metabolite in humans under pathological conditions.

High-resolution gas chromatography of the 22 tetrachlorodibenzo-p-dioxin isomers.

ABSTRACT The 22 tetrachlorodibenzo-p-dioxins (TCDDs) were synthesized in microgram quantities by a simple pyrolysis procedure from different potassium chlorophenates. The separation of these TCDD isomers was studied on high-resolution glass capillary columns with different stationary phases (Silar 10c, OV-17, OV-101) and using mass spectrometric detection. Conditions were found that allowed the unambiguous assignment of many of these isomers, including the very toxic 2378-TCDD. The determination of the various TCDD isomers is illustrated in the analysis of samples from known contaminated areas in Seveso, Italy and in eastern Missouri, and the method is also applied to the analysis of fish from the Tittabawassee river in Michigan and fly ash samples from municipal incinerators in Switzerland.

Reproducibility of the pyrolysis—gas chromatography of the cis-1,4-polyisoprenes NR and IR : Influence of the chromatographic separation

Good reproducibility of the pyrolysis—gas chromatography of vulcanized rubbers is difficult because of their insolubility, the presence of additives and the complexity of the pyrograms. With cis-1,4-polyisoprenes, the quantitative results are considerably improved by using a high-resolution glass capillary column instead of a packed column. The relative standard deviation is about 1% for the main peaks and is still less than 5% for several small peaks.

Mass spectral fragmentation of phthalic acid esters.

Phthalic acid esters are among the most frequently encountered pollutants in biological extracts. They are very often detected in biological analysis using gas chromatography. Even using high resolution glass capillary columns, the identification of some of these esters remains difficult. In this paper the mass spectral fragmentation of a large number of phthalic acid esters is presented. Some criteria for the identification of the type of isomerism on the aromatic ring and the identification of the ester functions are also presented.

Glass Capillary Columns In The Gas Chromatographic And Gas Chkomatocraphic-Mass Spectrometry Determination Of Trace Levels Of Kepone In Natural Waters

Abstract The application of high-resolution glass capillary columns to the analysis for Kepone in environmental samples by gas chromatography and gas chromatography-mass spectrometry is described. Glass capillary columns make possible the rapid screening and analysis of Kepone at a lower detection limit of 2 ng/L in natural waters. However, even with the aid of glass capillary columns, electron capture determinations for Kepone are suDJect to error. The use of isopropanol in solutions containing Kepone was found to reduce the variability of the Kepone detector response by as much as six times. A discussion concerning the intricacies of Kepone analysis in natural waters is given.

Analysis of some older Scandinavian formulations of 2,4-dichlorophenoxy acetic acid and 2,4,5-trichlorophenoxy acetic acid for contents of chlorinated dibenzo-p-dioxins and dibenzofurans.

Ten samples of older formulations of 2,4,5-trichlorophenoxy acetic acid and 2,4-dichlorophenoxy acetic acid used in Sweden were analyzed for chlorinated dibenzo-p-dioxins and dibenzofurans. The analyses were performed with gas chromatography/mass spectrometry with a high resolution glass capillary column for maximum isomeric separation and sensitivity. The detection limit was 0.01-0.05 ppm. The amounts of contaminants were of the same order of magnitude as that found earlier in European samples with later production dates (late 1960s and 1970s).

Advances in two‐dimensional GC with glass capillary columns

AbstractA versatile two‐dimensional gas chromatograph is described, consisting of 2 separate ovens, one intermediate trap, an auxiliary inlet, and the necessary hardware to effect off‐line switching according to the principle of Deans. The unit has been designed for use with high resolution glass capillary columns. The performance of individual instrumental components was critically evaluated. Results showed that low dead volume glass to metal connections were required in the manifold and detector lines to minimize extra‐column effects. The mass of the intermediate trap must be low to allow rapid heating. Operational parameters are discussed and examples of some applications are shown.

Transformation of arachidonic acid into 12-hydroxy-5,8,10,14-eicosatetraenoic acid by mouse peritoneal macrophages

Mouse peritoneal macrophages were incubated at 37°C for 30 min with arachidonic acid (all- cis-5,8,11,14-eicosatetraenoic acid). Oxygenation of arachidonic acid in mouse peritoneal macrophages occurs by two major pathways: fatty acid cyclooxygenase and lipoxygenase. The major metabolite of the latter is 12-hydroxy-5,8,10,14-eicosatetraenoic acid which was identified by gas liquid chromatography on high resolution glass capillary column and mass spectrometry.

Use of High Resolution Glass Capillary Columns for the Analysis of Pesticides in River and Drinking Water

High resolution glass capillary columns (60 m) were evaluated for routine use in the analysis of extremely low levels of chlorinated hydrocarbon insecticides commonly encountered in river and drinking water samples. Resolution produced by these columns permitted gas chromatography of sample extracts without extensive and time-intensive column chromatography preparation. Modifications of a popular, inexpensive gas chromatograph, necessary for the use of capillary columns, are described. Detection limits, separation numbers (TZ), and relative retention times on the SE-30 capillary columns are provided for several insecticides.

Qualitative analysis of multi-component s-triazine herbicides by gas-liquid chromatography

It has been found that in the analysis of multi-component mixtures of s-triazines on packed columns some problems arise in that on non-polar stationary liquids (OV-101, SE-30) many peaks of s-triazines overlap and some peaks are not symmetrical, depending on the support material. Separations on a polar phase (Carbowax 20M) were better, but still inadequate.A complex mixture of chloro-, methoxy- and methylthio-s-triazines was separated successfully on high resolution glass capillary columns coated with Carbowax 20M. The optimal temperature for the analysis of s-triazines was determined from the dependence or log R, on 1/T. For the characterization of s-triazins in environmental samples, Kováts retention indices were measured on glass capillary columns with dynamically coated non-polar (OV-101) and polar (Carbowax 20M) stationary liquids. The relationship between the structures of the s-triazines and their retention data was studied.

Qualitative and semi-quantitative analysis of the non-polar organic fraction of air particulate matter

A simple method is presented for the rapid analysis of the non-polar organic fraction of air particulate matter (quality control of air). The method is based on heat desorption of the volatile organic material directly in the injector of a gas chromatograph, followed by separation of the compounds on a high-resolution glass capillary gas chromatographic column. Complete analysis can be performed in as little as 5 h.

Determination of Arene Oxides by a Gas Chromatography-Mass Spectrometry System: Thermal Reactions of 9, 10-Epoxy-9, 10-Dihydrophenanthrene

Abstract An analytical technique involving the use of a gas chromatograph coupled to a mass spectrometer-computer system, has been developed to detect arene oxides using 9, 10-epoxy-9, 10-dihydro-phenanthrene as a model substrate. The gas chromatograph was equipped with a hydrogen flame ionization detector and a high-resolution glass capillary column coated with SE-52 (methyl phenyl silicone). Two simultaneous thermal reactions (deoxygenation and rearrangement) of 9, 10-epoxy-9, 10-dihydrophenanthrene in the gas chromatograph were observed. The method developed was compared with a conventional method utilizing a packed glass column. Under the latter conditions neither thermal reactions nor 9, 10-epoxy-9, 10-dihydrophenanthrene were detected. The identification of the reactant and products was achieved by comparison of retention times and mass spectral fragmentation patterns obtained from authentic samples.

Use of hydrolyzed chlorosilanes for the preparation of high resolution glass capillary columns

A new procedure for the preparation of high resolution open tubular glass capillary columns is described. This procedure involves the preparation of polysiloxane polymers obtained by alkaline hydrolysis of alkyl chlorosilane. The mixture of polysiloxane polymers is then coated on the wall of previously HCl treated glass capillary columns using a dynamic method. A base-catalysed reaction using gaseous ammonia, applied to the coated polymers leads to a stable chemically bonded stationary phase, with non-polar characteristics. This type of column is easier to prepare than conventional ones and exhibits excellent chromatographic properties, both with regard to their resolution, stability and reproducibility. The flexibility of this method permits the use of other types of commercially available chlorosilanes (i.e. methylphenyl chlorosilane) to prepare polar polysiloxane polymers suitable for analysis of complex biochemical mixtures, such as steroid metabolites.

A micro electron capture detector for temperature programmed analysis with capillary columns for a wide range of applications

The electron capture detector (ECD) has become a indispensable and widely used tool for the detection of halogenated compounds in gas chromatography. The ECD is successfully used for routine analysis particularly in the field of environmental survey, residue determination in the food and agriculture chemistry and even more so in clinical chemistry. However, its application with high resolution glass capillary columns revealed a substantial drawback of existing ECD's, primarily the relatively large internal detector volume. The micro ECD described, with its very small cell volume (∼140 mm3), particularly designed for use with high resolution capillary columns, minimizes drastically the loss of separation efficiency since diffusion effects are negligible. The micro ECD permits the use of splitless or split injection techniques, as well as temperature programmed analysis to optimize sample separation. Very stable baseline and low noise conditions lower the detection limits considerably (∼2 pg Lindane full scale). The micro ECD can be operated either with direct current, pulsed frequency or constant current modes. Examples demonstrating the capabilities of this detector include the detection of halogenated organic volatiles in water at subnanogram levels, the determination of PCB's and pesticide residues in food as well as selected analysis in clinical chemistry, such as bile acids and amino acids in body fluids.