Wide-bore capillary column for the direct analysis of ethanolamines and ethylene glycols

Summary The GC separation of a mixture of three ethanolamines and four ethylene glycols without any preliminary derivatization, on a wide-bore capillary column coated with Carbowax 20M is described. These high-boiling and polar compounds elute giving simmetrical peaks and show good resolution. The analysis is completed in less than 14 minutes.     

Gas chromatographic separation of ethanolamines and ethylene glycols without preliminary derivatization

Summary An effective and rapid GC separation of ethanolamines, even in the presence of ethylene glycols, using short glass capillary columns is developed. No preliminary derivatisation of the sample is necessary. The separation is completed in 6 minutes.     

Gas chromatographic separation of expoxystyrenes on carbowax 20 M capillary column

Summary The separation of some epoxystyrenes on fused silica capillary columns coated with poly(ethylene glycol) was investigated, Retention indices were determined at two temperatures to interpret chromatographic behaviour, The standard deviation was 0.3 index units.     

Inverse gas chromatographic characterization of Porapak Q as an extractant of pollutants from aqueous media

The surface of Porapak Q was characterized by inverse gas chromatography (IGC) carried out by the determination of dispersive and specific adsorption components of Porapak Q surface, calculating γ_s^d and -ΔH _a^s parameters, respectively. An interpretation was given based on the chemical structure of Porapak Q. The obtained results were confirmed through the surface Lewis acidity and basicity constants, K _a and K _b, respectively, correlating well with the determined thermodynamic parameters.     

Headspace gas chromatographic determination of ethylene oxide in air

Summary A simple and accurate headspace-GC method is described to determine the amount of ethylene oxide which has been collected from air using adsorption tubes containing activated charcoal and a relatively safe desorbing agent (N,N-dimethyl acetamide). The detection limit is 40μg/m³.     

A rapid gas chromatographic method for the analysis of acidic fermentation products

Summary A rapid and simple method for the identification of acidic fermentation products is described. Methyl esters of volatile and non-volatile acids are separated on a single chromatographic column. Retention time data for a number of acids are tabulated.     

Use of backflushing and peak-cutting technique in gas chromatographic trace analysis

Summary A backflusing, peak-cutting method was developed for the analysis of trace components present in the tail of a major component peak. Using a helium-ionization detector, the minimum detectable concentration (MDC) was: oxygen in hydrogen, 0.5ppm; nitrogen in oxygen or argon, 1ppm; and methane and carbon monoxide in nitrogen, 1ppm. The corresponding MDC values for the conventional single-column method were 7.2ppm, 8.3ppm, and 14 and 5ppm, respectively. Equations used to predict the retention time are given. The accuracy of the predicted retention time is about two percent compared to experimental results.     

Derivatization of amines with chloroformate esters for gas chromatographic analysis

Summary The gas chromatographic analysis of amines after conversion to electron capture sensitive carbamates in two-phase systems has been studied. Hydrophilic compounds, for instance methylamine, are reacted with 2,2,2-trichloro-tert. butyl chloroformate. Quantitation below 10^–7 M can be made by thermionic or electron capture detection. A hydrophobic amine, namely N,N-dimethyl-n-octylamine, was derivatized with 2,4,6-tribromophenyl chloroformate with addition of iodide ion to the aqueous phase. The favorable effect of iodide ion as well as the choice of pH and chloroformate ester is discussed.Presented at the 14th International Symposium on Chromatography London, September, 1982     

New clean-up method for gas chromatographic analysis of pyrethroid residues

Summary A fast and efficient method has been developed for clean-up of fenpropathrin and fluvalinate for gas chromatographic determination of their residues in crops, grain and soil. Charcoal (Darco-G-60) was used as adsorbent and the pyrethroids recovered by washing the adsorbent with hexane-acetone (9∶1). The method provides a clear filtrate with no interfering peaks in the chromatogram. Recoveries ranged 91.00–100%.     

Analysis of reaction by-products in ethylene oligomers by capillary gas chromatography

Summary A gas chromatographic method using temperature-programmed poly-dimethylsiloxane OV-101 and poly(pheny ether) (5 rings) capillary columns was developed to separate and quantify the reaction by-products in ethylene oligomers. It was found that the content of 2-alkyl-1-alkenes, 2-alkenes and n-alkanes in the C₈–C₁₈ -olefin fractions amounts to 29, 10 and 2.6% respectively.     

The structure and chromatographic properties of poly(ethylene glycol) 20M layer on the surface of a diatomaceous earth type support

Summary The properties of poly(ethylene glycol) 20M (PEG 20M) coated on the hydroxylated surface of Chromaton N AW were investigated by inverse gas chromatography. It was found that the solid form of PEG 20M exhibits partition as the retention mechanism even below its melting range. The contribution of adsorption to the specific retention volume was also determined. It was demonstrated that inverse gas chromatography establishes the existence of a polymer surface layer but precise determination of its thickness is difficult. The limitation of the applicability of inverse gas chromatography results from the structure of the investigated surface layer which is thin and not coherent so that solute molecules can penetrate it.     

Sampling device for a simple,fast calibration technique in gas chromatographic trace analysis of gas phases and vapor phases

In order to accommodate continually changing tasks in the [μl/l]–[nl/m³] ranges of gas chromatographic trace analysis of gas phases and vapor phases, a simple and time-saving calibration technique is presented which renders unnecessary conventional test mixtures of the abovementioned concentration ranges. This new method is based on the simulation of such mixtures at the inlet of the GC unit with the aid of commercially available multiway sampling valves of various volumes by means of partial pressure sampling.     

Gas chromatography with mass spectrometry for the quantification of ethylene glycol ethers in different household cleaning products

A rapid and simple procedure is reported for the determination of six ethylene glycol ethers in cleaning products and detergents using gas chromatography with mass spectrometry. The analytes were extracted from 2.0 g samples in acetonitrile (3 mL) and the extract was submitted to a clean‐up step by QuEChERS method, using a mixture containing 0.3 g magnesium sulfate, 0.15 g primary/secondary amine, and 0.05 g C₁₈. The clean acetonitrile extract (1 μL) was injected into the chromatographic system. No matrix effect was observed, so the quantification of the samples was carried out against external standards. Detection limits were in the range 3.0–27 ng/g for the six ethylene glycol ethers. The recoveries obtained, using the optimized procedure, were in the 89.4–118% range, with relative standard deviations lower than 14%. Twenty‐three different household cleaning products, including glass cleaner, degreaser, floor, softeners, and clothes and dishwashing detergents, were analyzed. Large interindividual variations were observed between samples and compounds.     

Direct gas chromatographic analysis of halogenated hydrocarbons at the part-per-trillion level

Large sample volume on-column injection (up to 250 μL) of n-pentane solutions of halogenated hydrocarbons has been employed for the direct measurement of both low-boiling and high-boiling compounds in what is essentially a single run. Two-bonded phase, fused-silica capillary columns are joined in series, through which the low-boiling compounds are first chromatographed and detected with an electron capture detector. High-boiling compounds are then trapped in a section joining the two columns, and subsequently chromatographed in the second column, using the same detector. This procedure permits analysis at the ppt level.     

A routine gas chromatographic method for the analysis of chlorofluorocarbons in aerosol cans

Summary A gas chromatographic (GC) method for the routine analysis of fully halogenated chlorofluorocarbons (CFCs) in aerosol cans is described. The identification of CFCs by GC was found to be in full agreement with those by GC-mass-spectrometery. The method has been applied to the analysis of CFCs in 448 aerosol products. The most commonly used fully halogenated CFC propellants in aerosol cans were found to be CFC11, CFC12 and CFC114.     

A fast derivatization procedure for gas chromatographic analysis of perfluorinated organic acids

A rapid and simple derivatization procedure has been developed for gas chromatographic determination of perfluorinated organic acids (PFCAs, C₆–C₁₂), using isobutyl chloroformate (IBCF) to convert the acids into the more volatile isobutyl esters, under catalysis by pyridine. The procedure was optimized in an acetonitrile medium and applied to GC techniques with electron-capture detection (GC-ECD) and mass spectrometry with electron-impact ionization (GC-EI-MS); for the sake of comparison, HPLC with electrospray-ionization MS (HPLC-ESI(−)-MS) was also tested. The LOD and LOQ values obtained for these three techniques were compared, and the lowest LODs were obtained with GC-ECD (0.06–1.80 μg mL⁻¹). The procedure was further optimized in an aqueous medium, obtaining the best results in a phosphate buffer (pH 2.5, 50 mmol L⁻¹), in which the LOD and LOQ values were measured for GC-ECD a GC-EI-MS. The lowest LODs were found for GC-EI-MS (0.030–0.314 μg mL⁻¹). The practical applicability was tested on Vltava river water samples.     

Development of gas chromatographic method for determination of cholesterol oxides in meat products

Summary A method of extraction, purification and gas chromatographic analysis of five cholesterol oxidation products (COPs) (7β-hydroxycholesterol, 5α, 6α-epoxycholesterol, 25-hydroxycholesterol, 7-ketocholesterol and cholestane-3β, 5α, 6β-triol) has been developed. The method is aimed at the determination of COPs in meat and meat products, in particular dry sausages, where large differences in the content of cholesterol and its oxidation derivatives may occur. Linearity of response of trimethylsilyl ethers was defined. The minimum concentration tested was 2.5 μg g⁻¹ in the injected solution. The main feature of the present work is the addition of a purification step of unsaponifiables by SPE on silica cartridges. Extraction recoveries of COP standard mixtures, performed with or without the SPE step, are evaluated. The introduction of the clean-up step results in high purity samples without further losses in the entire process.     

In situ fabrication of microporous organic network coated capillary column for high resolution gas chromatographic separation of hydrocarbons

Microporous organic networks (MONs) are a new class of porous materials synthesized via Sonogashira coupling reactions between organic building blocks. Here we report an in situ synthesis approach to fabricate MONs coated capillary column for high resolution GC separation of hydrocarbons. The McReynolds constant evaluation reveals the MONs coated capillary is a non‐polar column. The MONs coated capillary column shows good resolution for GC separation of diverse important industrial hydrocarbons such as linear and branched alkanes, alkylbenzenes, pinene isomers, ethylbenzene and styrene, cyclohexane and benzene. The MONs coated capillary column gave a high column efficiency of 1542 plates per meter for hexane and good precision for replicate separations of the selected hydrocarbons with the RSDs of 0.2–0.3, 1.5–3.1, and 1.9–3.3% for retention time, peak height and peak area, respectively. The MONs coated capillary also offered better resolution than commercial Inert Cap‐1 and Inert Cap‐5 capillary columns for hexane and heptane isomers. These results reveal the potential of MONs as novel stationary phases in GC.