bluuebunny/crossref_metadata_2025_split huggingface dataset:
Selective determination of oxygenates in complex samples with the O‐FID analyzer
Authors: Verga G. R. , Sironi A. , Schneider W. , Frohne J. Ch. 
Published: May 2005

AbstractA gas‐chromatographic analyzer allowing the selective detection of individual oxygenates in complex organic mixtures, such as gasolines, is described. The analyzer is based on the oxygen‐specific response flame ionization detection (O‐FID) method. The system operates with capillary columns and includes a cracking reactor to convert any oxygenate to carbon monoxide and a special FID equipped with a microreactor for the catalytic hydro‐genation of CO and detection as methane. Hydrocarbons give no signal. The selectivity of the method is better than 1:107 and the linear range approaches 105. The analysis of modern fuels containing oxygenated additives, to improve octane ratings, may greatly benefit from the proposed analytical method.
Coupling micro‐LC and capillary GC as a powerful tool for the analysis of complex mixtures
Authors: Duquet D. , Dewaele C. , Verzele M. 
Published: May 2005

AbstractA multidimensional chromatography system with a packed fused silica Micro‐LC column connected on‐line with capillary gas chromatography is presented. The Micro‐LC column is used for group separation. Whole peaks are injected into the capillary GC column via an on‐column injector. The reproducibility of the proposed transfer system for polyaromatic hydrocarbons is 3% to 7% relative standard deviation. The potential of this on‐line Micro‐LC‐GC system is demonstrated by the analyses of PAH's and of a complex light gasoline fraction.
The effect of column characteristics on the minimum analyte concentration and the minimum detectable amount in capillary gas chromatography. Part II: The stationary phase film thickness
Authors: Noy Th. , Cramers C. 
Published: May 2005

AbstractFor a typical narrow bore (50 μm) and wide bore (320 μm) capillary column the effects of increased stationary phase film thickness (df) on the minimum detectable amount, Qo, as well as on the minimum analyte concentration, Co, are described. In treating the effect of an increased film thickness, two approaches can be followed; either the separation temperature is kept constant, resulting in larger values of the capacity ratio, k, or the column temperature is increased such as to keep k constant. For normalized chromatographic conditions the effects of both approaches on the minimum plate height, optimum carrier gas velocity, and required plate number are described, finally yielding expressions for Qo and Co for both mass flow and concentration sensitive detectors. At constant temperature, Co always increases with the film thickness for mass flow sensitive detectors (e.g. FID). Wide bore thin film columns offer the lowest value of Co attainable. For concentration sensitive detectors (e.g. TCD), Co is affected neither by column diameter nor by film thickness. The Qo–df plot for constant temperature shows a minimum, suggesting an optimum film thickness for mass flow sensitive as well as concentration sensitive detectors. The corresponding capacity ratio has a value between 0.5 and 1.5. At elevated temperatures (k constant) in combination with mass flow sensitive detectors, again an optimum film thickness exists, corresponding to a minimum value of Co. For constant capacity ratio Qo always increases with the film thickness for both types of detectors. As indicated above, in some situations the lowest values of Co and Qo are obtained at an increased film thickness, the effect being marginal. As an initial guideline, for the daily practice of capillary gas chromatography with respect to minimum values of Co and Qo, the use of thin film columns is to be preferred.
Analysis of dexamethasone, triamcinolone, and their metabolites in human urine by microcolumn liquid and capillary gas chromatography mass spectrometry
Authors: Rodchenkov G. M. , Uralets V. P. , Semenov V. A. , Leclercq P. A. 
Published: May 2005

AbstractAdult male volunteers were administered orally 10 mg of the espective drug. Urine samples were investigated by micro‐column liquid chromatography and capillary gas chromatography combined with on‐line mass spectrometry. The former technique was found to be usable for the detection of these drugs. The latter method appeared to be superior in terms of sensitivity and for metabolism studies. The major excretion products of dexamethasone were identified as isomeric 6‐hydroxy metabolites. Dexamethasone as such and its 20‐hydroxy metabolite were found in minor quantities. Unlike dexamethasone, triamcinolone is excreted largely unchanged from the human body. Two metabolites were identified as 11‐keto and 4,5‐dihydrotriamcinolone. With the gas chromatography methods developed, abuse of these drugs can be detected up to 24 h after administration of a 5 mg single dose.
New method for the preparation of small diameter columns with polymeric stationary phases for open tubular liquid chromatography
Authors: Dluzneski P. R. , Jorgenson J. W. 
Published: May 2005

AbstractThe purpose of this report is to introduce a new method for use in coating polymeric stationary phase films on the inside wall of small bore diameter fused silica capillary tubing. This technique is being developed for use in fabricating capillary columns for open tubular liquid chromatography.
Cyclodextrins as chiral stationary phases in capillary gas chromatography. Part II: Heptakis(3‐O‐acetyl‐2,6‐di‐O‐pentyl)‐ß‐cyclodextrin
Authors: König W. A. , Lutz S. , Wenz G. , von der Bey E. 
Published: May 2005

AbstractHeptakis (3‐O‐acetyl‐2,6‐di‐O‐pentyl)‐ß‐cyclodextrin is used as a chiral stationary phase in capillary gas chromatography. High enantioselectivity towards trifluoro‐acetylated α and β‐chiral amines, amino alcohols, α‐ and β‐amino acid esters, and cyclic trans‐diols is observed. In contrast to chiral polysiloxane phases, where hydrogen bonding interaction is essential for enantiomer separation, in cyclodextrins inclusion properties contribute to enantioselectivity. This can be concluded from the separation of N‐alkylated amino compounds. The new chiral stationary phase exhibits a wide operating temperature range and is stable above 200°C.
Deactivation by polysiloxane and phenyl containing disilazane: A 29SI CP‐MAS NMR study after the formation of polysiloxane chains at the surface
Authors: Hetem M. , Rutten G. , van de Ven L. , de Haan J. , Cramers C. 
Published: May 2005

AbstractA high degree of deactivation of glass and fused‐silica capillary column walls is attainable by means of high temperature silylation (HTS) with or without a preceding leaching process. HTS with a phenyl containing disilazane, diphenyltetramethyldisilazane (DPTMDS), and polydimethylsiloxane (PDMS) are studied on Cab‐O‐Sil, a fumed silica, as a model substrate. Using 29Si CP‐MAS NMR, it was shown that no dimethylsiloxane chains were formed upon silylation with DPTMDS under different conditions of humidity and stoichiometry at 377°C. With DPTMDS deactivation it is possible that amino trisiloxy silane groups are formed, these groups add extra activity to the surface. Silylation with a PDMS, OV 101, at various temperatures between 300°–420°C did show that dimethylsiloxane chains were bonded at the surface. Using the 29Si CP‐MAS NMR technique with variable contact times to reveal siloxy group mobility, the degradation of dimethylsiloxane chains at the surface was studied. PDMS degradation at an optimal temperature gives a more effective diminuation of the silane activity caused by chemical reaction with the silanol groups and the effective screening of the remaining silanol groups with anchored polydimethylsiloxane chains and small cyclodimethylsiloxane ring structures at the surface.
Co‐solvent effects for preventing broadening or loss of early eluted peaks when using concurrent solvent evaporation in capillary GC. Part 2: n‐Heptane in n‐pentane as an example
Authors: Grob Konrad , Müller Eugen 
Published: May 2005

AbstractCo‐solvent effects are applied to allow use of concurrent solvent evaporation for applications requiring analysis of compounds eluted less than some 50° above the column temperature during sample introduction, i.e. at oven temperatures below some 100–120°C. Required conditions such as GC even temperature, concentration of the co‐solvent and length of the uncoated pre‐column (retention gap) are studied theoretically as well as experimentally for the case of n‐heptane as co‐solvent in n‐pentane.
PTV splitless injection of sample volumes up to 20 μl
Authors: Grob Konrad , Li Zhangwan 
Published: May 2005

AbstractPTV splitless injection cannot compete with on‐column injection as far as simplicity, reliability, and accuracy of quantitative analysis is concerned. However, PTV splitless injection is attractive for trace analysis of samples containing high concentrations of involatile sample by‐products. Maximum injection volumes are limited by the amount of liquid that can be retained within the PTV injector chamber and are around 20–30 μl injected at once. Solvent evaporation must be carried out in such a way that injector overflow is avoided.
Gas chromatographic and mass spectrometric characterization of isomeric alkylthiophenes (C20) and their occurrence in deep sea sediments
Authors: Rullkötter J. , Landgraf M. , Disko U. 
Published: May 2005

AbstractSix isomeric C20 alkylthiophenes were synthesized in order to prove the occurrence of such compounds in various deep sea sediments. As expected from the analogy with the corresponding saturated hydrocarbons, 2‐ and 3‐heptadecylthiophene have considerably longer relative retention times than the isomeric isoprenoid compounds, i.e. 2‐ and 3‐(4,8,12‐trimethyltridecyl)thiophene and 3‐ and 4‐methyl‐2‐(3,7,11‐trimethyldodecyl)thiophene. Covats retention indices for all compounds were determined by isothermal analysis at 190°C on two different silicone‐coated capillary columns. The mass spectra of the monoalkylated thiophenes show a base peak at m/z 98 corresponding to a Mcafferty rearrangement product in the case of the 3‐substituted isomers, whereas a simple benzylic cleavage dominates in the mass spectra of 2‐alkylthiophenes. 4‐Methyl‐2‐(3,7,11‐trimethylodecy)thiophene is an exception from this simple rule because also shows the McLafferty rearrangement as dominant fragmentation. Two of the isoprenoid thiophenes are prominent compounds in various deep sea sediments.
Analysis of turkish lignite tar by coupled LC/GC, GC/MS, and capillary SFC
Authors: Davies I. L. , Raynor M. W. , Urwin D. J. , Bartle K. D. , Tolay M. , Ekinci E. , Schwartz H. E. 
Published: May 2005

AbstractThis work describes the analysis of a pyrolysis product of a lignite sample obtained from the Turkish Goynuk reserve. The aliphatic, aromatic and polar compounds present in the tar are separated and identified by various chromatographic techniques: Capillary gas chromatography/mass spectrometry (GC/MS), on‐line high performance microbore liquid chromatography/capillary gas chromatography (LC/GC) and capillary supercritical fluid chromatography (SFC). The suitability of each technique for this particular application is discussed, and semi‐quantitative results are presented for the major components detected.
Automation in the chemical analysis of suspect arson samples by GC/MS. A systematic approach
Authors: Bertsch W. , Sellers C. S. , Babin K. , Holzer G. 
Published: May 2005

AbstractA method ist described that permits direct comparison of ion chromatograms between an isolate from a suspect fire debris sample and corresponding accelerant profiles. The system is highly automated and produces a diagnostic one page summary report for each sample. Side by side comparison of ion profiles is carried out between 4 common fuel types, e. g. gasoline, naphthenic type charcoal lighter fluid, mineral spirits, and kerosene, and the sample. Both qualitative and semiquantitative information is available. An on‐line search can also be carried out in which mass spectra are compared between components in a suspect sample and standards that are contained in an accelerant library. The system is flexible and requires only minimal interaction with the analyst.
Quantitative determination of volatiles in polyolefins by dynamic headspace/capillary gas chromatography/mass spectrometry
Authors: Hagman A. , Jacobsson S. 
Published: May 2005

AbstractThe possibilities of quantitative dynamic headspace by use of a multiple extraction method and an internal gas standard system for various classes of organic compounds in polyethylene and polypropylene are demonstrated. Numerous compounds can be analyzed over wide ranges of concentration and vapor pressure. However, the present study shows that the precision of the desorption parameters is of critical importance for assuring good quantitative results. The possibilities of using a theoretical model are also described. The recovery may be determined and the use of repeated desorption cycles can be reduced.
Gas chromatographic method for simulated distillation up to a boiling point of 750°C using temperature‐programmed injection and high temperature fused silica wide‐bore columns
Authors: Curvers J. , van den Engel P. 
Published: May 2005

AbstractIt is demonstrated that linear injection characteristics are obtained for a wide boiling point range sample using a temperature‐programmed injector in combination with wide‐bore fused silica columns. The applicability of the described combination for high temperature simulated distillation is described. The method, using external standardization, gives accurate and repeatable results for different types of samples in the boiling range between 50 and 750°C. The lifetime of the fused silica wide‐bore columns was found to be acceptable, viz. over 80 temperature‐programmed cycles between ambient and 430°C. Some comments are made on the accuracy of boiling points for normal alkanes.
Cyclodextrins as chiral stationary phases in capillary gas chromatography. Part IV: Heptakis(2,3,6‐tri‐O‐pentyl)‐β‐cyclodextrin
Authors: König W. A. , Lutz S. , Hagen M. , Krebber R. , Wenz G. , Baldenius K. , Ehlers J. , Dieck H. Tom 
Published: May 2005

AbstractO‐Perpentylated β‐cyclodextrin has been evaluated as chiral stationary phase in capillary gas chromatography. Enantioselectivity is observed towards many chiral hydroxy compounds, including cyanohydrins and carbohydrates. Most importantly, the enantiomers of many olefins and alkyl halides can be resolved on this chiral phase. The thermal stability of the cyclodextrin derivative exceeds 200°C.
Gas chromatographic analysis of traces of light hydrocarbons. A review of different systems in practice
Authors: Schaeffer Hans‐Jörg 
Published: May 2005

AbstractIn recent years air quality and atmospheric investigations have become very important topics. This results from a new legal basis for environmental protection which generates the need for the accurate measurement of ambient conditions. Despite the importance of these investigations, detailed reviews characterizing the existing analytical GC systems are scarce. The author has attempted to remedy this unsatisfactory situation by presenting a comprative review of the principal commercially available systems as well as some homemade set‐ups. No single method will be optimal for all purposes. The system of choice will depend on the particular application and on the quality and composition of the sample. This review does not attempt to cover all existing systems, but some exotic or lesser known systems have also been included.
Determination of amino acids in human cerebrospinal fluid by gas chromatography
Authors: Labadarios D. , Moodie I. M. , Hough B. J. , Burger J. A. 
Published: May 2005

AbstractIn the present study, the use of gas chromatography (GC) for the determination of amino acids in human cerebrospinal fluid (CSF) is described. Although some amino acids may be determined using a packed column following the removal of glucose, the major interfering component, the inadequate resolution of other amino acids from remaining unidentified components results in poor quantitation. The use of wide bore columns improves reproducibility considerably, but still it does not provide sufficient resolution to enable quantitative determination of all amino acids in human CSF. Good reproducibility data, with CV values for all amino acids of 7% or less and recoveries generally between 80% and 100%, can only be obtained using the fused silica open tubular (FSOT) column. Normal amino acid levels are presented for 10 samples of human CSF, which compare well with data previously reported in the literature.
Preparation of high temperature stable glass capillary columns coated with PS‐090 (20% diphenyl substituted CH3O‐terminated polysiloxane) a selective stationary phase for the direct analysis of metal‐porphyrin complexes
Authors: Blum W. , Eglinton G. 
Published: May 2005

AbstractIn this report we describe the coating of delonized glass surfaces with commercially available CH3O‐terminated diphenyl‐dimethylpolysiloxane (PS‐090). This new type of reactive, high temperature stable stationary phases withstands temperatures up to 430°C. As already reported for OH‐terminated polymers, the underlying stabilization process is a condensation of methoxy groups of the phase with surface silanol groups arising from high temperature silylation. The good selectivity of this medium polar coating for substrates bearing π‐electron systems is demonstrated by the separation of various metalloporphyrins.
Detection limits of thermal conductivity and photoionization detectors in high speed narrow bore CGC
Authors: van Es A. , Cramers C. , Rijks J. 
Published: May 2005

AbstractNot only the required input band width and the availability of compatible instrumentation limit the reduction of column diameter but so do the column sample capacity and detector characteristics, such as volume and sensitivity. In this paper the scope and limitations of thermal conductivity and photoionization detection at atmospheric and reduced pressures for capillary gas chromatography are discussed at length.It is shown that the sensitivity of a thermal conductivity detector is inversely proportional to the pressure. Reduction of cell volume and decrease of pressure appear equivalent with respect to minimum detectable amount and peak broadening. This results in femtogram detection limits for column diameters as low as 10 μm.For photoionization detectors the sensitivity did not improve at reduced pressures, so that the effect of reduced pressure and addition of make‐up gas on the detection limits is the same. Nevertheless, the applicability of a low volume photoionization detector (40 μl) for capillary columns with a diameter as low as 50 μm will be demonstrated by series coupled PID and FID detectors and illustrated with various applications.
Capturing of volatiles emitted by living plants by means of thick film open tubular traps
Authors: Bicchi C. , D'Amato A. , David F. , Sandra P. 
Published: May 2005

AbstractFused silica open tubular traps coated with a 15μm film of methyl silicone have been successfully applied to capture volatiles emitted by living plants. The atmosphere surrounding the plants is sucked through the trap where the volatiles are retained. After sampling, the trap is installed as pre‐column in a multidimensional CGC system. The volatiles are thermally desorbed, reconcentrated in a cold trap and analyzed on‐line on the analytical capillary column.
The solvent venting injection technique in capillary supercritical fluid chromatography
Authors: Berg B. E. , Greibrokk T. 
Published: May 2005

AbstractA solvent venting technique for injection of volumes up to 1 μl on 50 μm i.d. SFC columns has been compared to direct injection methods. The peak broadening and peak splitting observed with direct injection have been examined and found to be related to the starting pressure, the column temperature, and the sample solvent, in addition to the sample volume. The solvent venting technique removed peak splitting and improved the column efficiency. With a proper selection of experimental conditions, the sample recovery was 100%. The major part of the solvent was eluted in 15–20 s. Several applications have been demonstrated.
Structure‐retention correlation in CGC
Authors: Hanai Toshihiko , Hong Cai 
Published: May 2005

AbstractThe retention time of 24 alkanes (Al‐Al), 11 olefins (OI), 17 alkyl alcohols (Al‐OH), 30 fatty acid methyl esters (FA) and 8 polyaromatic hydrocarbons (PAH) was measured on non‐polar CP‐Sil‐5 and DB‐1 and polar CP‐WAX‐52 and DB‐WAX capillary columns at different temperatures.The correlation coefficients of the capacity ratios of each group of compounds and that of all the compounds together was excellent; however, there was some selectivity of different types of compounds when their capacity ratios were correlated with their Van der Waals volumes. The elution order of these compounds was Al‐Al < OI < FA < Al‐OH < PAH on both non‐polar columns, while the retention of PAH was greater on the DB‐1 column and those of other compounds were greater on the CP‐Sil‐5‐column. Such selectivity was significant on polar columns.Further, the energy effect, which was used to make a retention index system in liquid chromatography, was obtained from their capacity ratios to make a retention index system for capillary column gas chromatography. The values of the energy effect of each group of compounds were quite constant compared to the values obtained in liquid chromatography. The selectivity of these capillary columns was further discussed from their capacity ratios, their Kováts retention indices, and their energy effect to make a prediction of retention time.
Supercritical fluid extraction of 2,3,7,8‐tetrachlorodibenzo‐p‐dioxin from sediment samples
Authors: Onuska F. I. , Terry K. A. 
Published: May 2005

AbstractSupercritical fluid extraction (SFE) is a promising technique for the extraction of 2,3,7,8‐tetrachlorodibenzo‐p‐dioxin (2,3,7,8‐TCDD) from environmental matrices such as contaminated sediments. The ability of SFE to solubilize many organic contaminants is well documented in industrial processes but its analytical applications were exploited just recently. In this study supercritical carbon dioxide and nitrous oxide and their mixtures with 2% methanol were used to extract 2,3,7,8‐TCDD from aquatic sediments. An attractive feature of this process is that the carbon dioxide, being a virtually inert fluid, leaves no solvent residue on the processed sediment. Almost 100% of the 2,3,7,8‐TCDD can be extracted from a sediment spiked with 200 μg/kg 2,3,7,8‐TCDD in 30 minutes by using supercritical carbon dioxide + 2% methanol. Cleanup procedure is compared with the Soxhlet extraction procedure currently used as a standard method for extracting dioxins from sediment samples.
Group‐type fractionation of petroleum and alternative fuels by column liquid chromatography
Authors: Lanças F. M. , Carrilho E. , Deane G. H. N. , Camilo M. C. F. 
Published: May 2005

AbstractThe present paper introduces an instrumental procedure based on column liquid chromatography for the total analysis of petroleum heavy ends and similar samples. The procedure avoids the precipitation of asphaltenes and asphaltols. One sequence of eluents fractionates the sample into 8 fractions: 5 non‐polar (hydrocarbons), one intermediate (resins), and 2 polar fractions (asphaltenes and asphaltols).Quantitative results from gravimetric measurements and UV‐Vis and FTIR spectra of fractions obtained from petroleum heavy ends are presented, as well as those from GC/MS data obtained from one fraction obtained from liquefaction of biomass. The method presented is easy to set up and operate, requires minimum operator attention, is reliable (no precipitation), reproducible, and inexpensive.