bluuebunny/crossref_metadata_2025_split huggingface dataset:
Evaluation of gas chromatography coupled with ion mobility spectrometry for monitoring vinyl chloride and other chlorinated and aromatic compounds in air samples
Authors: Simpson Greg , Klasmeier Maren , Hill Herbert , Atkinson David , Radolovich G. , Lopez‐Avila Viorica , Jones T. L. 
Published: May 2005

AbstractThe objective of this research was to evaluate, in the laboratory, the potential of gas chromatography/ion mobility spectrometry (GC/IMS) for monitoring vinyl chloride and other organic compounds in air samples in the field. It was determined that GC/IMS has the potential to directly detect vinyl chloride in air at the 2 ppbv level, and when concentrated on an adsorbent trap from a 1 L sample of air, detection could be lowered to the 0.02 ppbv level. From a comparative investigation of 18 EPA priority pollutants and 34 common vapor‐phase organic compounds, many compounds were found to provide a more sensitive response in IMS than vinyl chloride, indicating that GC/IMS would be broadly applicable to the direct detection of vapor‐phase organics in air.Operating parameters including drift gas, spectrometer temperature, and sample‐inlet position were evaluated and discussed with respect to sensitivity and resolution. High temperature dramatically increased sensitivity to vinyl chloride. Vinyl chloride was shown to produce both negative and positive ion mobility spectra, with the negative‐mode spectra resulting from electron‐capture dissociation of the vinyl chloride. The limit of detection for vinyl chloride was found to be 7 pg/s. Limits of detection for 18 EPA priority pollutants were determined and compared to vinyl chloride. The responses of 34 other vapor‐phase organic compounds were also compared to that of vinyl chloride. Non‐selective, positive‐ion detection of 30 of the 34 compounds was demonstrated along with selective, electron‐capture‐type detection of 29 of them. Chloride‐specific and bromide‐specific detection illustrated the advantages of selected‐ion monitoring in IMS.
A modified inlet system for high speed gas chromatography using inert metal tubing with a carbon dioxide cooled cryotrap
Authors: Li Wenhai C. , Andrews Anthony R. J. 
Published: May 2005

AbstractTen different metal tubings were investigated for thermal decomposition of analytes when used as the trap tube in a cryotrap/thermodesorption inlet system. No noticeable sample decomposition of hydrocarbons, chlorinated hydrocarbons and a brominated hydrocarbon was observed for six of the tubings with hydrogen as the carrier gas. This observation may be partly attributed to the developed deactivation techniques that produce inert metal tubings that are being widely adopted by many column manufacturers, the different trap materials used in comparison to previous studies and the decreased sample residence time in the hot trap tube. A cryotrap using carbon dioxide was constructed and tested as a alternative to the previously used liquid nitrogen based systems. This cryotrap was able to trap compounds with a boiling point of 80°C.
Analysis of naturally occurring α‐acetotriacylglycerides by gas chromatography — chemical ionization mass spectrometry
Authors: Spitzer Volker , Aichholz Reiner 
Published: May 2005

AbstractThe seed oils of three Maytenus species have been examined by high temperature GLC using SOP‐50 (methoxy‐terminated) and OV‐225‐OH (OH‐terminated) glasscapillary columns. The main compounds (71–76%) could be identified as α‐mono‐acetotriacylglycerols by a combination of high temperature GLC‐MS in negative chemical ionization mode with a CH4/N2O mixture as reactant gas and other spectroscopical methods (infrared, 1H‐ and 13C‐nuclear magnetic resonance spectroscopy). The OV‐225‐OH phase demonstrated better separation properties that the SOP‐50 phase for this substance class and up to eight species of α‐monoacetotriacylglycerols could be separated. The content of usual triacyclglycerols was below 1%. The results of the analysis of the individual fatty acids as their methyl esters by GC and GC‐MS are also presented.
Alcohol modifiers in MEKC with SDS as surfactant. Study on the influence of the alcohol chain length (C1C12)
Authors: Van Hove Erik , Szücs Roman , Sandra Pat 
Published: May 2005

AbstractThe influence of alcohol modifiers with different chain length on the migration time window in micellar electrokinetic chromatography (MEKC) has been studied. Highly polar alcohols like methanol and 1‐propanol are typical aqueous phase modifiers. Higher alcohols like 1‐butanol, 1‐pentanol and 1‐hexanol influence the micellar structure and are considered as micellar phase modifiers. The effect of long chain alcohols is small because of their low applicable concentrations.
Deactivation of silica surfaces with a silanol‐terminated polysiloxane; structural sharacterization by inverse gas chromatography and solid‐state NMR
Authors: Scholten Alex B. , de Haan Jan W. , Janssen Hans‐Gerd , van de Ven Leo J. M. , Cramers Carel A. 
Published: May 2005

AbstractRetention gape deactivated with Silicone OV‐1701‐OH show good chromatographic performance and remarkable stability against water induced stationary phase degradrdation. In an attempt to better understand the findamentals off the deactivation process using silanol terminated polysiloxanes, a fumed silica was deactivated with Silicon OV‐1701‐OH. In contrast to fused silic capillaries, fumed silica (Aerosil A‐200) can be studied by 29Si cross‐polarization magic‐angle‐spinning (CPMAS) NMR, thus serving as a model substrate for fused silica. Retention data from inverse gas chromatography at infinite dilurion and 29Si CP MAS NMR data of five Aerosil phases, differing in residual silanol surface concentration, are correlated with the aim of validating this approach for stationary phase characterization. A comparatively detailed model of the deactivating polymer layer that explains the observed absorption activities is deduced.Surface silanols are shown to play a key role in the polymer layer, the structure of which is of primary importance for the absorption behavior after deactivation. Contrary to common belief, the absolute silanol surface concentration after deativation is only of secondary importance for the overall absorption activity. High silanol surface concentrations enhance degradation of the polysiloxane chains into small cyclic fragments as well as subsequent absorption and immobolization to the silica substrate surface. The mobility of linear polysiloxane chains in the kHz regime (as determined bby NMR cross‐polarization dynamics) appears to determine the extent which the residual silanols are accessible for analytes. It is therefore anticipated that there is an optimum silanol surface concentration of fused silica surfaces to be deactivated with silanol terminated polysiloxanes; it should be lazrge enough to adsord polymer fragments, but not large to avoid excessive residual silanol activity.
Modified capillary GC/MS system enabling dynamic headspace sampling with on‐line cryofocusing and cold on‐column injection of liquid samples
Authors: Barcatolo Robertiono , Casson Pierino 
Published: May 2005

AbstractThe paper describes a capillary GC/MS hardware arrangement allowong either:
on‐line injection of sample of gases and vapors coming from dynamic headspace or purg & trap samplers and their subsequent cryofocusing/thermal desorption prior to the analytical capillary column (first column):
direct injection of liquid samples through a cold on‐column injector into a second analytical column (counted in series with the first).
Chromatographic profiles of acacia honey aromas provide condirmation of the suitability of this system.
Investigation of fulvic acids from peat using capillary electrophoresis (CE)
Authors: Ciavatta Claudio , Govi Marco , Gessa Carlo 
Published: May 2005

AbstractThe aim of this work was to characterize the fulvic acids (FA) extracted from peat by use of capillary electrophoresis (CE). Two FA extracts have been obtained using two different extractants (0.1 M NaOH and 0.1 M NaOH plus 0.1 M Na4P2O7, Na+PP). The CE runs wre performed using a coated silica capillary, and several buffer solutions at different PH values. The results obtained show that the Fa extracts may be well characterized by CE even if the isolelectric point of the fulvic compounds is very low. The best fractionation has been obtained using a buffer borate at PH 8.9 as funning buffer. The charcterization of the two extracts also showed some important differences between the NaOH extract and the Na+PP extract.
Gas chromatographic separation of chiral organochlorines on modified cyclodextrin phases and results of marine biota samples
Authors: Vetter Walter , Klobes Ulkrike , Hummert Kerstin , Luckas Bernd 
Published: May 2005

AbstractFour chiral stationary phases containing modified cyclodextrines diluted in or chemically bonded to a non‐chiral phase were used to resolve chiral organochlorine compounds such as α‐hexachlorocyclohexane (α‐HCH), perdeuterated α‐HCH (α‐PDHCH), β‐and γ‐pentachlorocyclohexene (PCCH), oxychlordane, cis‐and trans‐chlor‐ dane, cis‐ and trans‐heptachlorepoxide, PCB 95, PCB 132, PCB 149, and Chiral tozaphenes.The elution order was determined by analyzing standards with known enantiomeric excesses.Furthermore, an internal standard was used to even out slight variations in the ratio of peak hights of enantiomers which were determined from injection to injection.None of the chiral stationary phases resolved all chiral organochlorine compounds. However, the β‐TBDM(35% heptakis (6‐O‐t‐butyldimethylsilyl‐2,3‐di‐O‐methyl)‐β‐cyclodextrin in OV 1701) column allowed the separation of all compounds under investigation except for PCB 95 and chiral toxaphenes.Emphasis was placed on the separation of as many as possible enantiomers on a chiral phase by application of one temperature program and with respect to unambiguous quantitation of biological samples such as bludder and liver of marine and terrestrial mammals.
Factors influencing breakthrough volumes when using sorption traps at high flow rates
Authors: Laurens J. B. , Rohwer Egmond R. 
Published: May 2005

AbstractThe effects of the sample flow‐rate and bulk and bulk sample composition on the breakthrough behaviour of H2 in small sorption traps were studied. The information is required for the bulk thermal properties of the sample affect the temperature inside the cooled traps and therefore also the breakthrough volume. It was also found that the brakthrough volume, measured downstream of a packed trap, can qctually increase with volume flow rate.
Characterization of complex hydrocarbon mixtures using on‐line coupling of size‐exclusion chromatography and normal‐phase liquid chromatography to high‐resolution gas chromatography
Authors: Blomberg Jan , Mes Edwin P. C. , Schoenmakers Peter J. , van der Does Jan J. B. 
Published: May 2005

AbstractAn on‐line coupling of size‐exclusion Chromatography (SEC), normal‐phase liquid Chromatography (NPLC), and gas Chromatography (GC) for the characterization of complex hydrocarbon mixtures is described. The hyphenated system separates according to size, polarity, and boiling point. The use of size exclusion as the first separation step allows for the direct injection of complex (“dirty”) samples withont prior clean‐up. SEC‐NPLC coupling was realized using an on‐line solvent evaporator based on fully concurrent solvent evaporation (FCSE) using a modified loop‐type interface, vapor exit and co‐solvent trapping. Complete reconcentration of the analytes was realized by the introduction of a cryogenic cold trap. For the subsequent hydrocarbon group‐type separation an ammo‐silica column with n‐heptane as eluent was used. The NPLC‐GC coupling was based on an on‐column interface using partially concurrent solvent evaporation (PCSE) and an early vapor exit. Initial results obtained on the analysis of a residue from the atmospheric crude‐oil distillation (a so‐called long residue) are presented as an example of the enormous separation power of the SEC‐NPLC‐GC system. The application of the system for quantitative analysis has not yet been studied.
Determination of p,p′‐DDE and PCBs in adipose tissues using high‐performance liquid chromatography coupled on‐line to capillary GC – the EURAMIC study
Authors: Gort Steven M. , van der Hoff G. Rene , Baumann Robert A. , van Zoonen Piet , Martin‐Moreno Jose M. , van't Veer Piet 
Published: May 2005

AbstractLong‐term exposure to fat‐soluble xenobiotics is assessed by the concentration of DDE [1,1‐dichloro‐2,2‐bis(p‐chlorophenyl)ethyl‐ene], the persistent metabolite of DDT, in subcutaneous fat, aspirated from the buttocks of breast cancer patients and age‐matched controls, from five European centers collaborating in a case‐control study on breast cancer. In such studies using sample material of living subjects only small amounts of samples can be made available for analysis. In this particular study the only sample material available for the analysis of DDE were aliquots of the aspirates that were originally analyzed for fatty acids. Due to the small sample quantities available, e.g. aliquots of 200–800 p. 1, on‐line LC‐GC is most convenient because a major part of the sample can be used in the analytical procedure. In the LC‐GC procedure 50 μl of sample was injected on the LC column resulting in a 180 μl fraction containing the analytes of interest. The LC fraction was transferred to a capillary GC with electron capture detector by means of partially concurrent solvent evaporation. This way, sample handling is minimized thus reducing losses and preventing contamination. The feasibility of the on‐line LC‐GC system for the analysis of DDE is demonstrated with the analysis of 634 adipose tissue extracts in different series. The validity of this approach, using samples already analyzed for another parameter, with LC‐GC is clearly demonstrated by the fact that in over 97% of the samples DDE can be quantified. Thus rendering a meaningful data‐set for further epidemiological evaluation. The DDE levels found ranged from 0.99–3.13 μg/g adipose tissue.
Cyclodextrin‐modified micellar electrokinetic chromatography for separation of norgestrel enantiomers
Authors: Liu Yu , Gu Junling , Fu Ruonong 
Published: May 2005

AbstractA simple method for the separation of highly hydrophobic neutral enantiomers by cyclodextrin‐modified micellar electrokinetic chro‐matography (MEKC) is presented and strongly supported by experiments. The separation depends on the ratio between the concentrations of cyclodextrin (CD) and sodium dodecylsulfate (SDS) micelles and there is an optimum value of the ratio for the separation of the enantiomers of norgestrel and 4‐androstene‐3,17‐dione. At the optimum value of the ratio, obtained by adjusting the absolute concentrations of CD and SDS. The electrophoretic mobility difference between two enantiomers can be maintained nearly constant.
Signal enhancement in capillary electrophoresis by using a sleeve cell arrangement for optical detection
Authors: Djordjevic Nebojsa M. , Widder Martin , Kuhn Keinhard 
Published: May 2005

AbstractThis study comparts signal enhancement and efficiency in CZK employing three modes of detection: the sleeve cell (a simple method for creating a region of extended path length for absorption detection), the bubble cell (extended light path capillaries), and on‐column detection in 75 μm i.d. capillary. Flow profile in the sleeve cell was monitored under a microscope. An abrupt change in capillary diameter in the sleeve cell region (from 50 μm to 220 μm) did not produce extensive band broadening. The sleeve‐cell detection arrangement delivered a 3.5 fold increase in corrected peak area when compared with an oil‐column detection in 75 μm i.d. column.
Determination of chlorinated and brominated micropollutants by capillary gas chromatography coupled with on‐column radio frequency plasma atomic emission detection
Authors: Asp Tone Normann , Pedersen‐Bjergaard Stig , Greibrokk Tyge 
Published: May 2005

AbstractCapillary gas chromatography (GC) combined with on‐column radio frequency plasma atomic emission detection was evaluated for the determination of polychlorinated and polybrominated biphenyls (PCBs and PBBs). Quantitation was possible utilizing a single chlorine or bromine calibration curve based on a randomly selected reference compound, because the signal per ng of halogen ranged within 17 % for 29 congeners. Combined with an internal standard to correct for potential plasma quenching from matrix components, this type of universal quantitation represented a sub‐stantial simplification of current calibration procedures. In combi‐nation with relatively low detection limits (1–5 pg/s of halogen), the present work suggested that GC, coupled with on‐column atomic emission detection is a promising technique for the determination of halogenated micropollutants.
Enantioselective separations of chiral molecules by μ‐HPLC and SFC on microbore and packed microcapillary columns
Authors: D'Acquarica Ilaria , Gasparrini Francesco , Giannoli Barbara , Misiti Domenico , Villani Claudio , Mapelli Gian Pietro 
Published: May 2005

AbstractNew results obtained with microbore or microcapillary columns packed with DACH‐DNB CSP (spherical silica, 5 μm) using conventional LC eluents or supercritical fluids are reported. Examples of direct chromatographic separations of complex mixtures of stereo‐isomers on: a) long, packed microbore or microcapillary columns and b) several columns coupled in series are shown; in the latter case, a home‐made calculation procedure (Simulation for Multi‐Column Chromatography–SMCC) was used to quickly select the optimal conditions (kind of stationary phases and relative columns length).
Unusual fatty acids in compositae: γ‐Linolenic acid in Saussurea spp. seed oils
Authors: Tsevegsüren Nanzad , Aitzetmüller Kurt , Vosmann Klaus 
Published: May 2005

AbstractThe plant family Compositae is known to produce a set of unusual fattly acids in their seed oil. Saussurea, a genus of the Compositae is less studied in respect to the fatty acid compsition of their seed oil. Only Saussurea candicans was reported to contain crepenynic acid (33%) as seed oil component.In continuation of our exploration of the portential of wild oil seeds, fatty acids in seed oils of seven Saussurea species (S. amara, S. salicifolia, S. lipschitzii, S. pseudoalpina, S. pricei, S. parviflora, and S. dorogostaiskii) growing in Mongolia a were investigated by means of capillary GLC on capiallary columns of different selectivity (Silar 5 CP and BPX 70).γ‐Linolenic acid was found at levels up to 11% of the consitituent fatty acids of Saussurea spp. seed oils. This is the first time that γ‐Linolenic acid has been found in members of the plant family Compositae. Moreover, the number, position and configuration of the double bonds in γ‐linolenic acid and that of other fatty acids was additionally confirmed by silver ion thin layer chromatography and infrared spectroscopy. The occurence and distribution of γ‐linolenic acid, which has found considerable interest for pharmaceutical and dietary use, may be of chemotaxonomical significance in the plant family Compositae.
Enantiodifferentiation of α‐ketols in sherry by one‐ and two‐dimensional HRGC techniques
Authors: Häring Dietmar , König Thorsten , Withopf Barbara , Herderich Markus , Schreier Peter 
Published: May 2005

AbstractThe enantiomeric distrubution of solerone (5‐oxo‐4‐hexanolide) 1, ethyl 4‐hydroxy‐ 5‐oxohexanoate 2, ethyl 5‐hydroxy‐4‐oxohexanoate 3, 4‐oxo‐5‐hexanolide 4, and solerol (5‐hydroxy‐4‐hexanolide) 5 in sherry wines was determined by several HRGC techniques. While gas chromatography‐mass spectrometry on chiral cyclodextrin phases (chiral GC‐MS) prevented any racemization of α‐ketols 2 and 3 caused by keto‐enol tautomerization during analysis, multidimensional gas chromatography MDGC (coupled either by “live‐T” switching or by “moving column stream switching” MCSS) led to rearranged constitutional‐and stereoisomers. The stereochemical results are discussed regarding the biogenesis of sherry constituents 1–5.
Influence of the lateral alkoxy chain length on the gas chromatographic properties of five liquid crystals
Authors: Perez F. , Berdagué P. , Courtieu J. , Bayle J. P. , Boudah S. , Guermouche M. H. 
Published: May 2005

AbstractThe gas Chromatographic properties of five laterally substituted liquid crystals are the subject of a comparative study. These liquid crystals belong to the homologous series: 2‐alkoxy‐3‐methyl‐4‐(4‐ethoxybenzoyl‐oxy)‐4′‐(4‐trans‐n‐pentyclcyclohexanecarboxyloxy) azobenzene, referred to as ALn, where n, the carbon number in the lateral alkoxy chain, is equal to 4, 6, 8, 10, or 12 carbon atoms. Their thermal properties were established by differential scanning calorimetry (DSC). It appears that the introduction of a lateral alkoxy chain affects the nematic temperature range which decreases when the carbon number increases. The chromatographic separation abilities of AL4, AL6, AL8, AL10, and AL12 were studied using capillary glass columns. The five liquid cystals are efficient before and after solid‐nematic or nematic‐liquid transitions; however, the plate numbers are higher in the nematic state. Interesting analytical properties were noted in various fields: iisomeric separation of alkanes, aromatics, polyaromatics, volatile aroma compounds, and cis and trans isomers. However, the chain length does not exert any great influence on the separation abilities.
Development of methods for testing barriers in food packaging materials
Authors: Aurela Birgit , Tapanila Tarja , Osmonen Riitta‐Maija , Söderhjelm Lliva 
Published: May 2005

AbstractIn some countries recycled materials are not allowed to come into contact with food without a protective layer such as plastic or virgin fiber. The purpose of this kind of barrier is to reduce migration of substances form beyond the barrier to the food. Two methods for studying a functional barrier are described. Both utilize migration cells in which one surface of the test specimen (for example a paper plate) is exposed to the food simulant. The first method involves the addition of indidcatsor substances to the non‐food contact layer. The second method is to measure the migration of substances originally present in the layers beyond the functional barrier layer. Several kinds of barrier used in commercial papaer plates were studied and differences between them were found.
Compehensive two‐dimensional gas chromatography (GC×GC) and its applicability to the characterization of complex (petrochemical) mixtures
Authors: Blomberg Jan , Schoenmakers Peter J. , Beens Jan , Tijssen Robert 
Published: May 2005

AbstractIn general, petrochemical products contain only a limited number of chemical classes of compounds (sample dimensionality). The enormous number of individual components within these classes, however, soon puts limitations upon a single chromatographic technique when it comes to adequate characterization of these products. Comprehensive two‐dimensional gas chromatography (GC×GC) clearly opens the possibility of estimating the composition of hydrocarbon mixtures in a far more detailed fashion than hitherto possible. Although the emphasis of papers of GCxGC thus far almost exclusively applies to the unsurpassed peak‐capacity, in the oil industry there is a need for characterization, rather than for analyzing all the individual compounds. In principle a GCxGC system can provide an almost perfect match between its intrinsic properties and the dimensionality of oil samples. To establish the applicability of GCxGC towards petrochemical analytical challenges, a commercially aavailable prototype instrument was subjected to an exhaustive characterization of a typical hydrocarbon precess stream and a fast characterization of a light gas oil. Although there are no fundamental limitations towards the quantitative aspects of a GCxGC system, this paper confines itself to qualitative results only. Quantitative aspects of GCxGC will be published in a forthcoming paper.