bluuebunny/crossref_metadata_2025_split huggingface dataset:
A novel algorithm for chromatogram matching in qualitative analysis
Authors: Mason John P. , Kirk Ian , Windsor Colin G. , Tipler Andy , Spragg Richard A. , Rendle Mark 
Published: May 2005

AbstractThe matching of the pattern of peaks produced during gas chromatography is of importance to many applications. At present, this task is generally performed manually, but this generates the usual problems associated with human inspection, such as a lack of objectivity and reproducibility, proneness to errors, and practical restriction of the volume of data which can reasonably be processed.This paper explores the use of a novel algorithm for automation of this task. The performance of the method on well controlled simulated data sets and real chromatograms is used to show not only how problems of manual inspection can be circumvented, but also how the existence of such a powerful method should open up the possibility of many new analyses for quality control, discrimination of varieties of sample, and the identification of specific components within a sample.
Splitless injection of up to hundreds of microliters of liquid samples in capillary GC: Part 1, concept
Authors: Grob Konrad , Brem Sandra , Fröhlich Dieter 
Published: May 2005

AbstractIf a sample evaporates by flash vaporization in an empty injector insert, the solute material is well mixed with the expanding solvent vapors and the maximum injection volume is determined by the requirement that no vapors must leave the vaporizing chamber. If evaporation occurs from a surface (e.g., of Tenax packing), however, the solvent evaporates first. The site of evaporation is cooled to the solvent's boiling point, and the cool island formed in the hot injector retains solutes of at least intermediate boiling point (visually observed for perylene). Solvent vapors, free from such solutes, may now expand backwards from the injector insert and leave through the septum purge exit. When solvent evaporation is complete, the site of evaporation warms up, causing the high boiling solutes to evaporate and to be carried into the column by the carrier gas. The technique somewhat resembles PTV injection, but is performed using a classical vaporizing injector.
Operational theory and instrumental implementation of the thermal gradient programmed gas chromatography (TGPGC) mode of analysis
Authors: Rubey Wayne A. 
Published: May 2005

AbstractThermal gradient programmed gas chromatography (TGPGC) separations involve the application of three‐dimensional thermal field programming. The operational aspects associated with TGPGC are such that rapid GC analyses can be achieved for complex and broad‐volatility‐range samples using open tubular columns with high thermal compliance, physical compactness, and geometric conformity. Elapsed times for TGPGC analyses of complex samples have ranged from 50 to 300 s. The application of rapidly changing thermal fields (or temperature surfaces) in TGPGC is accomplished through the use of a column sheath assembly. Recent research has centered upon different column sheath assembly designs and instrumental implementation of the TGPGC mode of operation. The instrumental implementation of the TGPGC mode for conducting GC and GC‐MS analyses places special demands upon the design and performance of numerous operational aspects of the system, e.g., the response‐time characteristics associated with analyte detection and the analytical output signal handling capabilities.
Recent advances in sample introduction for supercritical fluid chromatography
Authors: Kirschner Cynthia H. , Taylor Larry T. 
Published: May 2005

AbstractNew strategies for sample introduction in supercritical fluid chromatography are reviewed. Both open tubular and packed column systems are examined as the injection demands of each column type are addressed. In addition to advances made in solvent injection methods, supercritical fluid extraction (SFE) is discussed as a solventless injection technique for supercritical fluid chromatography.
Temperature program optimization by computer simulation for the capillary GC analysis of fatty acid methyl esters on biscyanopropyl siloxane phases
Authors: Sippola Erkki , David Frank , Sandra Pat 
Published: May 2005

AbstractThe selectivity of capillary columns coated with biscyanopropyl siloxane stationary phases for the separation of fatty acid methyl esters has been optimized by means of computer‐assisted column temperature optimization software. Temperature programming rates yielding the highest resolution in the shortest analysis time were selected for split, splitless, and on‐column injection operated in the constant pressure and pressure programmed modes.
Stereoisomeric flavor compounds, part LXI: Enantioselective analysis of aroma‐relevant dihydrofuranones
Authors: Bruche Günther , Dietrich Armin , Mosandl Armin 
Published: May 2005

AbstractThe odor impression of the pure enantiomers of various chiral dihydrofuranones which are important flavor compounds has been evaluated by sniffing the well separated optical antipodes in the GC eluate from heptakis(2,3‐di‐O‐methyl‐6‐TBDMS)‐β‐cyclodextrin as the chiral phase for capillary gas chromato‐graphic separation. Liquid chromatographic separation has been achieved by the use of bonded β‐cyclodextrin as the chiral stationary phase and methanol–water as eluent. Enantiomer separation in the latter was improved by addition of triethylammonium acetate to the eluent.
Determination of organotin compounds in environmental samples by supercritical fluid extraction and gas chromatography with atomic emission detection
Authors: Liu Yan , Lopez‐Avila Viorica , Alcaraz Marcela , Beckert Werner F. 
Published: May 2005

AbstractThe extraction of six tetraalkyltin and seven ionic organotin compounds from spiked topsoil samples with supercritical carbon dioxide and carbon dioxide modified with 5 percent methanol was investigated. Analysis of the soil extracts was performed by gas chromatography with atomic emission detection. Retention times, minimum detectable concentrations, and detector linear ranges are included for nine organotin compounds (seven of the nine compounds were derivatized with n‐pentylmagnesium bromide prior to gas chromatographic analysis). A 23 factorial experimental design was used to study the effect of three variables (pressure, temperature, and extraction time) on compound recovery. The results indicate that the tetraalkyltin compounds are extracted from topsoil samples with recoveries ranging from 90 to 110 percent. Recoveries for the ionic organotin compounds ranged from 50 to 75 percent for trimethyltin chloride, triethyltin bromide, and tributyltin iodide; they were below 20 percent for dimethyltin dichloride, dibutyltin dichloride, diphenyltin dichloride, and butyltin trichloride. When sodium diethyldithiocarbamate was added to the soil samples prior to extraction, followed by extraction with carbon dioxide modified with 5 percent methanol, recoveries ranged from 70 to 90 percent for trimethyltin chloride, triethyltin bromide, dimethyltin dichloride, tributyltin iodide, and dibutyltin dichloride; recoveries were approximately 40 percent for butyltin trichloride and diphenyltin dichloride.
GC‐MS identification of styrene and oligomers in polystyrene plastic for milk packaging. Headspace and solution injection technique
Authors: Abrantes Shirley 
Published: May 2005

AbstractTwenty compounds have been determined by GC‐MS in polystyrene used for milk packaging. The major components identified in milk were styrene and its dimer at concentrations of 13 and 43 mg/kg, respectively. The detection limit for styrene by the equilibrium headspace method was 0.29 mg/kg. Another method used to determine the concentration of styrene and its dimer in milk was the use of acetone to precipitate the proteins and extract both the fat and the residues from the plastic packaging. The solution obtained was then directly injected into the GC. The detection limits were found to be 0.16 mg/kg for styrene and 0.28 mg/kg for the dimer. The solution injection method thus proved to be much more sensitive.
Experimental design optimization of the separation of the aromatic compounds in petroleum cuts by supercritical fluid chromatography
Authors: Fraile Rebeca , Sánchez Vicente 
Published: May 2005

AbstractA experimental design optimization method is demonstrated for evaluation of the resolution of the performance mixture used in the proposed ASTM test to determine the aromatic content of aviation fuels. The method uses a Doehlert experimental matrix test to optimize the resolution and analysis time by varying the pressure and temperature of the supercritical carbon dioxide mobile phase. The separation between saturated and aromatic compounds was optimized using only seven experiments. With this procedure, the analysis time required for determination of the total aromatic content of more complex samples can be reduced to less than 10 min.
Gas chromatographic enantiomer separation with modified cyclodextrins: Carboxylic acid esters and epoxides
Authors: König Wilfried A. , Gehrcke Bärbel 
Published: May 2005

AbstractThe wide range of application of 2,6‐di‐O‐methyl‐3‐O‐pentyl‐β‐and y‐cyclodextrins is demonstrated by the resolution of the enantiomers of the methyl esters of chiral carboxylic acids: α and β hydroxy acids with up to 18 carbon atoms, hydroxy di‐ and tricarboxylic acids, and alkyl/aryl‐substituted carboxylic acid methyl esters, including the plant hormone abscisic acid, insect juvenile hormones, and some non‐steroidal anti‐inflammatory drugs can be resolved with generally large separation factors. The new cyclodextrin derivatives also exhibit high selectivity for epoxides.
Stainless steel capillary columns for high temperature gas chromatography
Authors: Zou Naizhong , Yusheng Tsui , Jiahe Sun , Wanzhen Lu 
Published: May 2005

AbstractA layer of elemental silicon has been deposited on the surface of stainless steel tubing by means of chemical vapor deposition (CVD). Two kinds of capillary column were prepared from the deactivated tubing: cross‐linked, silanol‐terminated polydime‐thylsiloxane wall coated open tubular (WCOT) columns and molecular sieve 13X porous layer open tubular (PLOT) columns. Unlike fused silica capillary columns, stainless steel WCOT and PLOT columns can be operated at temperatures in excess of 400°C. High temperature simulated distillation has been performed successfully with a macro bore WCOT column and rapid PNA (paraffin, naphthene, and aromatic) analysis with a multidimensional gas solid chromatographic (GSC) system using PLOT columns.
The use of nitrous oxide for supercritical fluid extraction of pharmaceutical compounds from animal feed
Authors: Sauvage E. , Rocca J.‐L. , Toussaint G. 
Published: May 2005

AbstractSupercritical fluid extraction (SFE) coupled “off‐line” with HPLC analysis has been applied to pharmaceutical analysis: two different matrixes (rodent and dog feed) were spiked with compounds under investigation in pharmacological studies in order to study the supercritical extraction of such matrixes prior to further analysis and quantification of the compounds of interest.The fluid flow‐rate in the SFE system was governed by the geometric characteristics (internal diameter and length) of the linear fused silica capillaries. The changes in fluid flow‐rate, between experiments, for each new restrictor, required the introduction of the term Total Gaseous Fluid Volume (TGFV), which enabled a series of extraction results to be compared.The comparative behavior of nitrous oxide and carbon dioxide as supercritical extraction fluids was investigated. Results obtained using pure supercritical fluids with high solvating power (density 0.79 g ml−1) and fluids modified with a polar liquid solvent (methanol and acetonitrile) are discussed.
Stereoisomeric flavor compounds. Part LXV: Preparative resolution of the enantiomers of chiral dihydrofuranones by recycling chromatography
Authors: Bruche Günther , Mosandl Armin , Kinkel Joachim N. 
Published: May 2005

AbstractPreparative resolution of the enantiomers of several chiral dihydrofuranones, known to be important flavor compounds, has been achieved by combining the use of bonded β‐cyclo‐dextrin as chiral stationary phase with closed‐loop recycling chromatography. The purity of the separated enantiomers has been determined by chirospecific capillary GC analysis, using heptakis(2,3‐di‐O‐methyl‐6‐TBDMS)‐β‐cyclodextrin as the chiral stationary phase.
Memory effects in gas chromatographic detection with a microwave‐induced plasma
Authors: Valente Antonio Luiz Pires , Uden Peter C. 
Published: May 2005

AbstractCapillary gas chromatography coupled to microwave‐inducedplasma detection furnishes sensitivity adequate for trace analysis when the signal is monitored at a carbon emission line. Work performed with one of these systems at high electronic gain for the carbon signal has revealed solvent band widths in excess of four minutes; these impeded quantification of peaks eluting after the solvent. This report discusses two phenomena which could be related to the unexpected intensity of this solvent response: photomultiplier tube saturation and carbon deposits in the quartz plasma discharge tube.
An instance of temperature‐dependent elution order of enantiomers from a chiral brush‐type HPLC column
Authors: Pirkle William H. , Murray Patrick G. 
Published: May 2005

AbstractTypically, reduction of column temperature increases the enantioselectivity of a chiral stationary phase. An instance in which progressive reduction of temperature initially reduces enantioselectivity, then inverts the elution order of the enantiomers, and finally causes enantioselectivity to increase has been observed. This behavior is related to the nature and concentration of the polar modifier in the mobile phase, and requires particular chiral phase‐analyte‐mobile phase combinations. A rationalization is presented as to the possible origin of this behavior. This rationale may aid in finding other examples of this temperature‐dependent elution order of enantiomers and ultimately increase our understanding of chiral recognition processes.
Chirasil‐Dex‐TFA: A new polysiloxane‐bonded and immobilizable cyclodextrin stationary phase for enantiomer separation by GC
Authors: Jung Martin , Schurig Volker 
Published: May 2005

AbstractHeptakis(2,6‐di‐O‐methyl‐3‐O‐trifluoroacetyl)‐†‐cyclodextrin has been chemically bonded to a polydimethylsiloxane via an octamethylene spacer and subsequently immobilized on to the surface of fused silica capillaries, the first time a cyclodextrin derivative with mixed substituents has been immobilized in this way. The enantioselectivity of the new chiral stationary phase has been investigated as a function of the cyclodextrin content. It was found to be higher than that reported for heptakis (2,6‐di‐O‐methyl‐3‐O‐trifluoroacetyl)‐†‐cyclodextrin or hepta‐kis(2,6‐di‐O‐methyl‐3‐O‐acetyl)‐†‐cyclodextrin dissolved in polysiloxane (e.g. OV‐1701). The degree of immobilization was over 90 %. The temperature stability is, however, inferior to that of Chirasil‐Dex (a permethylated cyclodextrin): the maximum operating temperature is approximately 200 °C.
Molecular modelling experiments on chiral recognition in GC with specially derivatized cyclodextrins as selectors
Authors: Kobor Frank , Angermund Klaus , Schomburg Gerhard 
Published: May 2005

AbstractThe results of gas chromatographic enantiomeric separations of selected non‐polar and polar test solutes (limonene and 1‐phenylethanol) using two different derivatives of β‐cyclodextrin, permethyl‐β‐CD and 2,3‐dimethyl‐tert‐butyldimethylsilyl‐β‐CD (PMCD and TBCD) are interpreted in combination with the conclusions from molecular modelling calculations based on docking experiments. A comparison of the two selectors which were used as solution in a polysiloxane matrix (OV 1701) indicated that the less flexible TBCD which is blocked on one side by the bulky tert‐butyldimethylsilyl groups seems to possess advantages for certain chiral separations, especially of the non‐polar type. The special properties of TBCD as selector are also demonstrated by chiral separations of other compounds.
An autosampler with a short transfer line for Curie point pyrolysis capillary gas chromatography
Authors: Onishi Akira , Endo Makoto , Uchino Shigeki , Harashima Naoto , Oguri Naoki 
Published: May 2005

AbstractA new multichannel autosampler which can automatically analyze up to twenty samples in sequence has been developed for Curie point pyrolysis – capillary GC. Compared with a previous system [1] the transfer line between the pyroysis unit and chromatograph is shorter, and thus has less dead volume, and can be operated at a higher temperature (300 °C). The relative yields of higher boiling point, highly polar, and thermally labile pyrolysates generated from polymers, and the reproducibility, were better than those obtained from the previous autosampler. To facilitate rapid operation an additional flow controller is installed on the new device to shorten the time taken to purge air from the sampler.
Separation of geometric isomers of metal β‐diketonates by supercritical fluid chromatography
Authors: Laintz Kenneth E. , Meguro Joshihiro , Iso Shuichi , Tachikawa Enzo 
Published: May 2005

AbstractThe separation of the geometric isomers of chromium and rhodium chelates of trifluoroacetylacetone and thenoyltrifluor‐oacetone was investigated using packed column supercritical fluid chromatography. Mobile phases consisting of neat and alcohol‐modified carbon dioxide were used, and the most favorable isomeric resolution was obtained with a phenyl stationary phase. The chromatographic performance was better for chelates with trifluoroacetylacetone than for the corresponding chelates with thenoyltrifluoroacetone. Chromatographic peak area analysis of the metal chelates investigated showed appropriate isomeric concentrations in the final diastereomeric products resulting from the synthetic procedures.
Residual solvent content in heatset offset print
Authors: Aurela Birgit , Räisänen Tapio 
Published: May 2005

AbstractA method was developed for measuring the residual solvent content in a dried offset print. The method is based on hexane extraction. The presence of additives and resins in the printing inks necessitated purification of the extract on an aluminum oxide column. In the study concerning the effect of the heatset web offset drying process on print quality, a distinct correlation was found between the residual solvent content of the print and the drying parameters.
Miniaturization of separation techniques using planar chip technology
Authors: Manz Andreas , Verpoorte Elisabeth , Effenhauser Carlo S. , Burggraf Norbert , Raymond Daniel E. , Harrison D. Jed , Widmer H. Michael 
Published: May 2005

AbstractMiniaturization of separation columns implies equally reduced vol‐ umes of injectors, detectors, and the connecting channels. Planar chip technology provides a powerful means for the fabrication of micron‐sized structures such as channels. This is demonstrated by two examples. An optical absorbance detector chip exhibits the expected behavior of a 1 mm optical path length cell despite its volume of 1 nL. A capillary electrophoresis device allows integrated injections of 100 pL samples, efficiencies of 70,000 to 160,000 theoretical plates in 10 to 20 seconds, and external laser‐induced fluorescence detection at any capillary length of choice between 5 and 50 mm.
Use of a temperature programmed injector with a packed liner for direct water analysis and on‐line reversed phase LC–GC
Authors: Mol Hans G. J. , Janssen Hans‐Gerd M. , Cramers Carel A. , Brinkman Udo A. Th. 
Published: May 2005

AbstractA system is described that allows the introduction of large volumes of water samples in capillary GC. Water elimination is carried out in the solvent split mode in a PTV injector with a packed liner. Two ways of separating water and analytes, i.e. evaporative and non‐evaporative (solid‐phase extraction), are compared. Sampling in the solid‐phase extraction mode is favorable both in terms of recovery as well as with regard to sampling time. Quantitative recovery is obtained for priority pollutants ranging in volatility from dimethyl‐phenol to phenanthrene. Losses occur for more volatile compounds, but even for these compounds the repeatability of the recoveries remains acceptable. With the system described here, water samples up to at least 1 ml of water can be directly analyzed. The detection limits are in the sub‐ppb range.
Capillary GLC fatty acid fingerprints of seed lipids—a tool in plant chemotaxonomy?
Authors: Aitzetmüller Kurt 
Published: May 2005

AbstractThe fatty acid composition of the seed lipids of plants, in contrast to leaf lipids, may contain highly specific unusual fatty acids, which are often correlated to plant family. For example, petroselinic acid is typical for the Apiacea family, cyclopropene fatty acids are typical for the Malvaceae family, and cyclopentene‐ring containing fatty acids for the Flacourtiaceae family. Other fatty acids may be characteristic for certain sub‐families or only for certain species of plants within a family or genus. γ‐Linolenic acid, Δ5–18:3 and Δ5–20:3 fatty acids and others may occur in several plant families, but are still linked to certain related species only. They can be analyzed by high‐resolution capillary GLC. Particularly interesting is the situation in the family Ranunculaceae. GLC fingerprints of fatty acids are shown that may indicate a closer or less close relationship between species within this family.
SFE of PAHs from soils with a high carbon content and analyte collection via combined liquid/solid trapping
Authors: Meyer Anja , Kleiböhmer Wolfgang , Cammann Karl 
Published: May 2005

AbstractPolynuclear aromatic hydrocarbons (PAHs) are recovered from a soil with a high carbon content (ca. 50%) with supercritical fluid extraction (SFE) as well as with conventional Soxhlet extraction. The influence of temperature and modifier volume on SFE efficiency and the effect of a combined liquid/solid trap for analyte collection are investigated in this study. Such traps, which make analyte collection and clean‐up possible in one step, are compared with conventional analyte collection in pure organic solvents. A comparison between reproducibility and efficiency of SFE and Soxhlet extraction is presented.
Investigation of high sensitivity GC‐FTIR as an analytical tool for structural identification
Authors: Jackson Peter , Dent Geoffrey , Carter David , Schofield Deborah J. , Chalmers John M. , Visser Tom , Vredenbregt Marjo 
Published: May 2005

AbstractAs part of a detailed investigation into the application of GC‐FTIR in industrial and environmental analysis, representative sets of samples have been analyzed in parallel using commercial high‐sensitivity instruments. Two of the instruments utilize low temperature storage of the GC eluate to extend the time available for FTIR analysis, yielding greater sensitivity than that possible by conventional ‘light‐pipe’ GC‐FTIR. In certain circumstances, instruments using both types of sample storage give rise to spectra exhibiting features characteristic of the interface used. Chromatographic resolution was found not to be significantly degraded by use of either sample storage interface. Particular advantages were found in having parallel flame ionization detection and mass spectrometry; this enabled the location of smaller components and gave greater certainty of identification.