bluuebunny/crossref_metadata_2025_split huggingface dataset:
Applications of a GC autosampler modified for headspace sampling
Authors: Penton Zelda 
Published: May 2005

AbstractA GC autosampler designed for liquid injection was modified for static headspace sampling. The modification was very simple and involved replacement of the standard 10‐μL syringe with a 100‐μL gas‐tight syringe. Liquid samples (0.2‐1.0 mL) were placed in 2‐mL vials, normally used for liquid sampling and an aliquot of the head‐space above the liquid was withdrawn and injected into the GC. All parts of the sampling system were at ambient temperature. The system was found to be useful for several applications. Among those discussed in this paper are determination of ethanol in the blood or urine of individuals suspected of driving while intoxicated, residual organic solvents in pharmaceuticals, and screening of effluent waters from industrial plants for acrylonitrile.
Rapid analysis of free medium‐chain fatty acids and related ethyl esters in beer using SPE and HRGC
Authors: Battistutta F. , Buiatti S. , Zenarola C. , Zironi R. 
Published: May 2005

AbstractA modification of a procedure by Hage [1] is proposed for the gas chromatographic evaluation of the content of free medium‐chain fatty acids and related ethyl esters in beer. The method involves extraction of free fatty acids and ethyl esters by SPE using C18 bonded phase columns, derivatization of free fatty acids and related ethyl esters with diazomethane, and GC analysis using an SP‐2340 capillary column. The results obtained have shown the method to be rapid and highly reproducible. The technique has been compared with other methods used for determination of free fatty acids.
Determination of neutral chlorinated extractable organic compounds in water samples using large volume on‐column injection capillary gas chomatography–mass spectrometry
Authors: Tamilarasan Ramasamy , Morabito Paul L. , Lamparski Les , Hazelwood Paul , Butt Alison 
Published: May 2005

AbstractAn automated large volume on‐column injection technique (LOCI) for capillary gas chromatography – mass spectrometry, GC‐MS, with solvent divert and heated retention gap technology has been used to simplify the method for determining sixteen neutral chlorinated extractable compounds (NCEC) in industrial plant process water samples at a level of 10 ng/L. According to the simplified procedure, 30 mL of water sample is extracted with 5 mL hexane, and 100 μL of the extract analyzed by combining large volume on‐column injection with mass‐selective detection operated in the selected ion monitoring mode. This combination has enabled simplification of the sample preparation and analysis procedures and provided a fast, labor‐saving technique for analyzing water samples. Simplifications include significant reduction of sample and eluent volumes during extraction, and elimination of the Kuderna‐Danish evaporative concentration step. The latter simplification has not only resulted in significant time savings, both during the analysis and for subsequent glassware cleaning; analyte losses and the introduction of contaminants and artifacts which may occur during this step have also been eliminated.System behavior, e.g. linearity of detector response, method detection limit, and reproducibility, were evaluated for all sixteen analytes using spiked water samples in the lower ng/L range. The response of the mass detector is linear in the range 5–20000 ppt for all sixteen NCEC investigated. Injection of 100 μL of sample using LOCI makes it possible to achieve an instrument detection limit in the ppt range. The calculated method detection limits are similar to those of the instrument precision and are lower than the required method detection limit of 10 ppt.Extraction efficiency has been maximized by optimizing sample‐to‐solvent ratio and extraction time. The extraction efficiency seems to be independent of sample‐to‐solvent ratio in the range of 2. 5 to 6 and increasing the extraction time from 25 to 120 minutes resulted in no significant increase in efficiency. Extraction efficiency also seems to be independent of the concentration of analyte in the water samples. The simplified procedure presented here was automated by means of a laboratory robot and used to generate all the extraction data reported in this manuscript.
Effect of ammonia carrier gas on the response of the flame ionization detector
Authors: Abdel‐Rehim Mohamed , Zhang Lin , Hassan Moustapha 
Published: May 2005

AbstractThe effect of using ammonia as a carrier gas on the response of the flame ionization detector (FID) has been investigated. It was found that the FID response, calculated as the effective carbon number (ECN), increased for all the compounds studied when ammonia, rather than helium, was used. The change was 0–0. 9 carbon atom for hydrocarbons, one carbon atom for alcohols and diphenyl ether, and 0.4–1 carbon atom for phenols and ketones. The increase in ECN was larger for amines (0. 8–5 carbon atoms), but these numbers also reflected an improvement in chromatographic performance as a result of reduced adsorption on the column. The largest change in signal‐to‐noise ratio, a six‐fold increase, was obtained for octyl‐amine; ratios for hexyl methyl ketone, diisobutyl ketone, dihexyl‐amine, dibutylamine, and N‐methyloctylamine increased by a factor of 2–3 when ammonia was used as carrier gas. To determine the extent to which the effect on detector response was solely attributable to ammonia, a mixture of 5 % ammonia in nitrogen was used as detector make‐up gas with helium as carrier gas. Under these conditions the noise in the FID increased but for most of the compounds studied the signal‐to‐noise ratio also increased.
Analysis of organomercury compounds in sediments by capillary GC with atomic fluorescence detection
Authors: Alli Azaam , Jaffé Rudolf , Jones Ronald 
Published: May 2005

AbstractAnalysis of methyl‐ and ethylmercury (MM and EM) halides in biological and environmental samples is generally performed by gas chromatography with electron capture detection. Tedious sample work‐up protocols and poor chromatographic response (using packed columns) have, however, shown the need for the development of new methods in this field.This paper reports a sensitive method, free from these deficiencies, for the determination of methyl‐ and ethylmercury. The organomercury compounds (MM and EM) are first released from the sample matrix, by the combined action of acidic potassium bromide and cupric ions, and then extracted into dichloromethane. The initial extracts are subjected to thiosulfate clean‐up and the organomercury species are isolated as their chloride derivatives by addition of cupric chloride, and subsequent extraction into a small volume of organic solvent. Capillary GC coupled with atomic fluorescence detection provided excellent separation efficiencies for methyl‐ and ethylmercury and proved to be a very selective and sensitive technique. The absolute detection limit for both MM and EM was found to be 0.2 pg.
Capillary electrophoresis separation of heterocyclic nitrosoamino acid‐conformers at sub‐ambient temperatures
Authors: Janini George M. , Muschik Gary M. , Issaq Haleem J. 
Published: May 2005

AbstractThe separation of a selected group of naturally occurring, heterocyclic nitrosoamino acids was achieved by capillary zone electrophoresis and the resolution of the syn and anti conformers improved as the temperature was lowered to 5 °C. The double peaks observed for each nitrosoamino acid are probably caused by the slow kinetics of conformational isomerism. The experimental setup consisted of a P/ACE 5510 electrophoresis system, a 57 cm polyacrylamidecoated capillary, and a 10 mM phosphate buffer, pH 7.2, containing 2 mM of 3‐(N‐N‐dimethylmyristylammonio)propanesulfonate (DMMAPS) and 0.1% Tween 20. Our study shows that (a) the lower the temperature, the greater the resolution and the longer the migration times; and (b) different nitrosoamino acid conformers were resolved at different temperatures because of differences in the rate of isomerization. For example, the conformers of N‐nitrosothiazolidine‐4‐carboxylic acid were partially resolved at 30 °C while those of N‐nitrosoproline were well resolved at the same temperature.
Liquid trapping after supercritical fluid extraction with modified carbon dioxide
Authors: Thompson P. G. , Taylor Larry T. 
Published: May 2005

AbstractA polarity test mix consisting of acetophenone, N,N‐dimethylaniline, naphthalene, 2‐naphthol, and n‐tetracosane was spiked onto sand and extracted with carbon dioxide modified with acetonitrile, methanol, or toluene. The extracts were collected in chloroform, hexane, methanol, or a mixed collection solvent consisting of equal parts chloroform‐hexane‐methanol. The mixed collection solvent which showed excellent recoveries for pure CO2, had the worst recoveries of all the collection solvents with modified CO2. Overall hexane was the best collection solvent studied for these analytes under these extraction conditions.
Direct coupling of capillary supercritical fluid chromatography with double‐focusing high resolution mass spectrometry
Authors: Bücherl T. , Eschler M. , Gruner A. , Palibroda N. , Wolff E. 
Published: May 2005

AbstractAn integral restrictor interface with jet separator for coupling capillary column supercritical fluid extraction – supercritical fluid chromatography with high resolution mass spectrometry (SFE‐SFC‐MS) has been built and used for the analysis of a fatty acid ester, and of polymer additives with a wide range of masses. The mobile phase used was supercritical carbon dioxide; a flame ionization detector (FID) was used in parallel with the mass spectrometer. Different SFC‐MS interface operating conditions, e.g. temperature, restrictor position, flow rate, and sample transfer conditions were optimized to obtain good sensitivity and separation for these applications. In addition, the sensitivity of measurements performed with the direct insertion probe and by SFC‐MS interface have been compared.
Analysis of atmospheric sulfur gases by capillary gas chromatography with atomic emission detection
Authors: Swan Hilton B. , Ivey John P. 
Published: May 2005

AbstractThe atomic emission detector (AED) has been found to be a sensitive and selective instrument for analysis of atmospheric sulfur gases by capillary gas chromatography. It was possible to determine atmospheric dimethyl sulfide at concentrations below 0.3 nmol/m3 typical of the remote marine environment in winter. Sample analyses from the Australian Baseline Air Pollution Station, Cape Grim, are used to illustrate this.In comparison with other sulfur‐specific detectors previously used for this work, the AED has been found to exhibit the best combination of specificity and sensitivity. A configuration comprising a series of valves, gas calibration loops, and a cryogenic trap prior to the GC‐AED was used for sample analysis. Standard addition of sulfur hexafluoride was found to assist determination of carbonyl sulfide, as it could be used to take into account the magnitude of signal quenching from coeluting gases. The AED was also found to be a selective detector for the direct injection of water‐soluble dimethyl sulfide oxidation products.
Identification of sterene compounds produced during the processing of edible oils
Authors: Mennie Darren , Moffat Colin F. , McGill Alister S. 
Published: May 2005

AbstractSamples of maize, rapeseed, soyabean, sunflower, and palm oils, collected at different stages in their respective refining processes, have been analyzed for the presence of dehydrated sterols (sterenes). A total of fifteen compounds were detected. Four have been characterized using model systems designed to investigate their formation. Their elemental composition, and that of the other eleven sterenes, was determined by high resolution mass spectrometry and structures assigned to a further six compounds. These included the ‐3,5‐, ‐2,5‐, ‐4,6‐,‐3,5,22‐, and ‐4,6,22‐ sterenes. Sterenes were not present in crude or alkali neutralized oils. Bleaching introduced a maximum concentration of 5 μg g−1 of total sterenes into the edible oils. Deodorization is the dominant stage in sterene production resulting in a maximum total concentration of 163 μg g−1. This increased concentration arises due to dehydration of the sterols and considerable isomerism of the sterenes.
On‐line recording of 13C/12C ratios and mass spectra in one gas chromatographic analysis
Authors: Meier‐Augenstein Wolfram 
Published: May 2005

AbstractAn isotope ratio mass spectrometer and an ion trap mass spectrometer have been coupled in parallel to one gas chromatograph. Using this arrangement both the 13C/12C ratio and the mass spectrum of a given compound can be measured simultaneously under identical gas chromatographic conditions. Although column connection fittings are employed to split the capillary eluate, chromatographic performance was barely impaired. Development of the system has been monitored by recording δ13C values of the constituents of Grob test mixture no. 2. The accuracy and reliability of system performance has also been tested.
Stereochemical differentiation and simultaneous analysis of 3‐, 4‐, and 5‐hydroxyalkanoic acids from biopolyesters by multidimensional gas chromatography
Authors: Kaunzinger Astrid , Podebrad Frank , Liske RÜDiger , Maas Birgit , Dietrich Armin , Mosandl Armin 
Published: May 2005

AbstractThe direct enantioselective analysis of 3‐, 4‐, and 5‐hydroxy fatty acids from biological material has been achieved by enantioselective multidimensional gas chromatography (enantio‐MDGC) with heptakis(2,3‐di‐O‐methyl‐6‐O‐tert‐butyldimethylsilyl)‐ or (2,3‐di‐O‐acetyl‐6‐O‐tert‐butyldimethylsilyl)‐β‐cyclodextrin as chiral stationary phase. All the bacteria investigated produced polyesters of enatiomerically pure (R) configured compounds.
A study of the compositional variation of the essential oil of ylang‐ylang (Cananga odorata Hook Fil. et Thomson, formagenuina) during flower development
Authors: Stashenko Elena E. , Torres William , Morales Jairo René Martinez 
Published: May 2005

AbstractVolatile secondary metabolites from Colombian ylang‐ylang flowers were obtained by combined steam distillation ‐ solvent extraction. The samples were analyzed by high resolution gas chromatography with flame ionization, nitrogen/phosphorus, or mass spectrometric detection. The chemical composition of the oils extracted from flowers at different stages of development differed both qualitatively and quantitatively. The generation of total volatile metabolites, light oxygenated compounds in particular, increased markedly during flower maturation. In this work the quality of the ylang‐ylang essential oils was studied as a function of flower maturity.
Evaluation of the performance of various universal and selective detectors for sulfur determination in natural gas
Authors: Tuan Hai Pham , Janssen Hans‐Gerd M. , Cramers Carel A. , Kuiper‐van Loo Ellen M. , Vlap Harm 
Published: May 2005

AbstractIn the present contribution, the performance of a number of commercially available selective and universal detectors that can be used in the analysis of sulfur components in natural gas is evaluated in terms of sensitivity, selectivity, reproducibility, quenching effect, stability, and compound dependence of the sulfur response. Investigated detectors include the sulfur chemiluminescnce, the flame photometric, the electron capture, the mass spectrometric, the thermal conductivity, and the flame ionization detector. The sulfur chemiluminescence detector was found to have the best overall performance, e.g., low picogram amounts of sulfur can be detected accurately and the linear dynamic range is more than five orders of magnitude. After careful optimization, the sulfur response of this detector was found to be almost compound independent. All other detectors, including the flame photometric and the electron capture detector, have more or less compound dependent responses.
A further study on the chiral separation power of a soluble neutral β‐cyclodextrin polymer
Authors: Ingelse Benno A. , Everaerts Frans M. , Sevcik Juraj , Stransky Zdenek , Fanali Salvatore 
Published: May 2005

AbstractEnantiomeric separation of some basic compounds, namely selegiline, amphetamine, and clenbuterol, was studied by capillary electrophoresis using an uncharged β‐cyclodextrin polymer added to the background electrolyte at pH 2.5. Both complexation and resolution were influenced by the concentration of the chiral polymer confirming our previous results obtained in our earlier work for a wide number of pharmaceutical compounds. In this further study, we examined the influence of different organic additives to the background electrolyte on the enantioselectivity of the chiral selector, also using an extended number of analytes. In most cases, the use of an organic additive resulted in a decrease of resolution. However opposite to that, in some cases, e.g. ephedrine, the organic solvent proved to be essential to achieve enantiomeric resolution. Furthermore the influence of the capillary temperature on the resolution of the analytes was evaluated. Increase of temperature had a deleterious effect on the resolution of the enantiomers. For ephedrine, however, relatively high temperature (50 °C) proved to be advantageous, for the resolution of the optical isomers.
Determination of hydroxycarbamates in aqueous matrices by direct derivatization and GC‐MS analysis in chemical ionization mode
Authors: Vincenti Marco , Minero Claudio , Lago Stefania , Rovida Costanza 
Published: May 2005

AbstractA rapid and effective procedure, developed for the determination of polar compounds in water, has been applied to hydroxycarbamates. In few minutes, it is possible to perform a catalyzed derivatization of such compounds directly in the aqueous medium, using n‐hexyl chloroformate. Extraction with n‐hexane and injection into a benchtop GC‐MS system are the only two further steps to complete the analysis. Chemical ionization proved to be more effective than electron impact to produce valuable mass spectra in terms of selectivity and sensitivity. Linear quantitative responses were demonstrated over a two‐order‐of‐magnitude range. The minimum detectable concentration was 3 ppb for acetohydroxamic acid and 10 ppb for hydroxyurethane, obtained from Po river water samples spiked with the two hydroxycarbamate standards.
Identification of volatile (micro) biological compounds from household waste and building materials by thermal desorption–capillary gas chromatography–mass spectroscopy
Authors: Wilkins Cornelius Kendall , Larsen Kjeld 
Published: May 2005

AbstractVolatile compounds from biodegradable household waste and infected building materials have been studied by dynamic or equilibrium headspace sampling and concentration on Tenax TA followed by thermal desorption and HRGC‐MS. Equilibrium headspace sampling was also used to study vegetables stored for 14–18 days at ambient temperature. Over 200 compounds were tentatively identified. The concentration of organic sulfur compounds from garden waste was high enough to contribute to respiratory problems of waste handling personnel. Nitriles, alkyl nitro compounds, and alkyl nitrates were isolated from radish and carrot samples at low concentrations (10–50 ppb). Air monitoring in waste handling working environments may be required to ensure the safety of personnel. Branched aliphatic aldehydes, carboxylic acids, esters, and 2‐alkanones were found in the headspace of the infected building materials, indicating that volatile compounds may be useful for detection of microbial growth in buildings.
GLC‐MS analysis of the fatty acids of the seed oil, triglycerides, and cyanolipid of Paulliania elegans (Sapindaceae) – a rich source of cis‐13‐eicosenoic acid (paullinic acid)
Authors: Spitzer Volker 
Published: May 2005

AbstractThe fatty acids of the total lipids, triglycerides, and the cyanolipid of Paullinia elegans (Sapindaceae) have been analyzed as their methyl esters and 4,4‐dimethyloxazoline derivatives by gas chromatography‐mass spectrometry. It was shown that the gas chromatographic separation of the oxazoline derivatives was sufficient to ensure the correct identification of the monoenic fatty acid positional isomers. Stereochemistry of the double bonds has been confirmed by infrared and 13C‐nuclear magnetic resonance (NMR) spectroscopy. cis‐13‐Eicosenoic Acid (Paullinic acid) (44.4%) and cis‐11‐octadecenoic acid (cis‐vaccenic acid) (19.8%) were found to be the main components beside other monoenoic acid positional isomers. The cyanolipid of P. elegans was identified as 2,4‐dihydroxy‐3‐methylenebutyronitrile derivative by IR, 1H‐NMR, 13C‐NMR spectroscopy and was quantified by 1H‐NMR spectroscopy (71.4%).
Microwave extraction in analytical chemistry of pollutants: Polychlorinated biphenyls
Authors: Onuska Francis I. , Terry Ken A. 
Published: May 2005

AbstractThe microwave energy produced by a high intensity microwave oven was used to extract polychlorinated biphenyls (PCB) from water samples. This static method was compared with liquid‐liquid extraction to determine the optimum and limiting conditions in extraction processes. The sample size and sample container shape determine the temperature profiles in the sample. Using a 500 mL sample size, the detection limit is in the low ng/L range when an electron capture detector is employed.
Solvent‐assisted supercritical fluid extraction for the isolation of semivolatile flavor compounds from the cinnamons of commerce and their separation by series‐coupled column gas chromatography
Authors: Miller Kenneth G. , Poole Colin F. , Chichila Tina M. P. 
Published: May 2005

AbstractSolvent‐assisted supercritical fluid extraction is superior to Soxhlet extraction, solvent extraction at reflux, and simultaneous setam distillation solvent extraction for the isolation of semivolatile compounds from the cinnamons of commerce. Optimized extraction conditions are described using carbon dioxide at 300 atm and 70°C to extract 0.5 g of powdered cinnamon mixed with 4.5 g of anhydrous sodium sulfate to which 1.0 ml of acetonitrile was added at the start of the sequential 30 min static and 30 min dynamic extraction. The semivolatile compounds were collected by solvent trapping in ethyl acetate and analyzed directly by series coupled‐column gas chromatography after filtration and partial solvent evaporation. Twenty‐one compounds identified by mass spectrometry were quantified in twenty‐four samples of cinnamon and cassia purchased in Sri Lanka, Korea, United Kingdom, and the United States of America. True cinnamon is easily distinguished from cassia by the presence of eugenol, absence of δ‐cadinene, much lower amounts of coumarin, and larger amounts of benzyl benzoate. Principal component analysis using the relative composition of the twelve major semivolatile compounds provides a clear distinction between true cinnamon and cassia as well as useful interspecies differences which can be used for further classification.
Sampling and gas chromatographic analysis of volatile organic compounds in hot and extremely humid emissions
Authors: Knobloch Thomas , Engewald Werner 
Published: May 2005

AbstractAdsorptive enrichment on hydrophobic adsorbents, thermal desorption, and capillary gas‐chromatographic analysis have been used to determine volatile organic compounds in extremely humid stack‐gas emissions from the residential burning of brown‐coal briquets. One hundred and fifty two compounds were identified and quantified. Quantitative emission factors were determined for the identified individual compounds in relation to the amount of the fuel used. These factors enable a first assessment of the pollution of the city of Leipzig with volatile organic compounds resulting from the burning of indigenous lignite.