bluuebunny/crossref_metadata_2025_split huggingface dataset:
Implications of the solvent effect in quantitative capillary gas chromatography of minor constituents in mixtures—a study using deuterium labeled and unlabeled benzofluoranthenes
Authors: Cretney W. J. , McLaughlin F. A. , Fowler B. R. 
Published: May 2005

AbstractPerdeuterated benzofluoranthenes have slightly shorter retention times than their equivalent unlabeled forms in a DB‐5 capillary column. Under column overload conditions, perdeuterated benzofluoranthenes in moderate multifold excesses, which might be encountered in their use as internal standards and carriers for quantitative analysis, are seen to exhibit both normal and reverse solvent effects on their close eluting congeners. In some cases the effects may be used to advantage by knowledgeable analysts, but for the ignorant and unwary the effects can lead to serious errors in identification and quantification.
Analysis of headspace samples using off‐line sorbent trapping coupled with automated thermal desorption and splitless injection onto a cryogenically cooled wide bore capillary column
Authors: Haynes L. V. , Steimle A. R. 
Published: May 2005

AbstractGas chromatographic equipment and procedures are described for automated splitless injection of pseudo‐static headspace samples collected externally onto a sorbent trap. The GC microprocessor controls, in sequence, carrier gas backflushing of the sorbent trap for water removal, splitless thermal desorption into a cryogenically cooled wide bore (0.53 mm i. d.) capillary column and oven temperature programming. The method has been routinely applied for profiling the mid‐to‐high boiling compounds (bp 80–225°C) in the headspace of a variety of foods and beverages. Method criteria, advantages and limitations are discussed. FID and NPD chromatograms for brewed coffee and peanut butter volatiles are presented as typical examples.
Gas chromatographic separation of PF3 substituted group 6 metal carbonyl complexes using serially‐coupled capillary columns
Authors: Hwang Wen‐Huan , Clark R. J. , Cooper W. T. 
Published: May 2005

AbstractThe retention of group 6 metal trifluorophosphine carbonyl compounds in serially‐coupled gas capillary columns has been studied as a function of different column configurations. For the trifluorophosphine‐substituted Mo, W, and Cr carbonyls, as well as the analogous Fe compounds, it was observed that the maximum resolution achievable by the coupled column technique was dependent on the order in which the nonpolar (DB‐1) and moderately polar (DB‐1701) columns were connected. The optimum configuration was different, however, for each series M(PF3)x(CO)6−x(M = Cr, Mo, or W) or Fe(PF3)x(CO)5−x. It was also observed that the use of coupled columns of dissimilar polarity can, in some cases, actually decrease resolution relative to that obtained by coupled identical columns (i. e. DB‐1 + DB‐1, or DB‐1701 + DB‐1701).
Isomer‐specific separation of 2,3,7,8‐class congeners of polychlorodibenzodioxins and ‐dibenzofurans on a smectic liquid‐crystalline stationary phase in capillary gas chromatography
Authors: Swerev M. , Ballschmiter K. 
Published: May 2005

AbstractA smectic liquid‐crystalline stationary phase was used in high resolution gas chromatography for the analysis of the patterns of the chloro‐homologues of the polychlorodibenzodioxins and polychlorodibenzofurans. Unique selectivity for most of the 2,3,7,8‐class congeners was observed. Use of this phase as an alternative to cyanopropylsilicone phases in the isomer‐specific analysis of halogenated and mixed halogenated dibenzodioxins and dibenzofurans is discussed.
Sampling of volatile components using a PTV in the solvent split mode
Authors: Herraiz M. , Reglero G. , Loyola E. , Herraiz T. 
Published: May 2005

AbstractSeveral packing materials were evaluated for their sampling performance with a cold programmed temperature vaporizing injector operated in the solvent split (solvent elimination) mode. Evaluations were made by comparing accuracy and precision of the data for mixtures of n‐alkanes, ethyl esters, n‐alcohols, and carboxylic acids covering polarity and volatility ranges typical of compounds present in food samples. Tenax exhibits the most desirable retention characteristics. Careful selection of the experimental conditions lowers losses of volatile compounds by co‐evaporation with the solvent and allows a reliably quantitative analysis. Coefficients of variation of relative (normalized) peak areas and absolute peak area ratios of each compound to the standard are generally less than 2%.
Identification of mononitropyrenes and mononitrofluoranthenes in air particulate matter via fused silica gas, chromatography combined with negative ion atmospheric pressure ionization mass spectrometry
Authors: Korfmacher W. A. , Rushing L. G. , Arey J. , Zielinska B. , Pitts J. N. 
Published: May 2005

AbstractThis paper describes the use of high resolution capillary gas chromatography combined with negative ion atmospheric pressure ionization mass spectrometry (NIAPIMS) for the analysis of an air particulate extract for mononitropyrenes and mononitrofluoranthenes, some of which are powerful bacterial mutagens. The results are compared to those obtained by the electron impact mass spectrometric analysis of the same sample In addition, the NIAPIMS method confirmed the identification of 4‐nitropyrene in the ambient air sample.
High performance liquid chromatographic determination of metoclopramide in plasma and urine and its application to biopharmaceutical investigations
Authors: Nieder M. , Jaeger H. 
Published: May 2005

AbstractAn optimized HPLC method for the quantification of metoclopramide (MCP) in human plasma and urine is described. MCP and internal standard are extracted from alkalinized substrate into diethyl ether and back‐extracted into dilute acid. The analytes are separated with a ternary mobile phase at cyanopropyl‐silica and detected at 312 nm (UV detection). The lower limit of quantification is 0.5 ng/ml in plasma and 50 ng/ml in urine. Optimization of extraction, chromatography, and detection is discussed. The method is selective to numerous common drug substances with excellent accuracy and precision data. After validation, the method is applied to the samples of a pharmacokinetic study. Pharmacokinetic parameters indicate the need for a sophisticated method as tool for optimization of metoclopramide formulations.
Interactions of aldehydes and ketones with the surface of fused silica capillary columns
Authors: Anthony L. J. , Holland R. A. , Heffner S. A. 
Published: May 2005

AbstractBy using gas chromatographic intermediate surface testing to study the surface properties of fused silica capillary tubing, the reversible adsorption of aldehydes and ketones on the fused silica surface has been observed for the first time. It is shown that this interaction can arise from the preferential interaction of carbonyl functional groups at bonded silanol sites on the surface. It is further shown that simple test mixtures containing aldehydes or ketones can be used to probe the concentration of water and bonded silanols on the surface and thus to evaluate capillary manufacturing processes and thermal and chemical surface treatments.
Dynamic headspace enrichment/reinjection for open tubular GC/FTIR analysis of volatiles in polymers
Authors: Schmidt S. , Blomberg L. , Wännman T. 
Published: May 2005

AbstractAn analytical system for the analysis of volatiles entrained in polymers is described. This system is based on a thermal desorption oven connected to a cold trap. After enrichment of headspace vapor, trapped material is reinjected and analyzed by open tubular gas chromatography/Fourier transform infrared spectroscopy, OTGC/FTIR. The thermal desorption oven is designed to provide different modes of sample introduction: use of a pyroprobe; insertion of a piece of quartz tubing with applied sample; or syringe injection. Headspace enrichment is carried out in a piece of fused silica capillary tubing filled with glass beads. The trap may be cooled either electrically using Peltier elements or with liquid nitrogen. A six‐port rotary valve is used for flow switching between enrichment and reinjection modes. All system parameters, temperatures, and timed events, are controlled from the gas chromatograph. Dynamic headspace analysis is demonstrated as a method for polymer characterization.
Comparison of thick film capillaries with packed columns from the point of view of loadability in combination with high resolving power
Authors: Ghijsen R. T. , Poppe H. 
Published: May 2005

AbstractThe present paper compares the potential of high pressure packed column gas chromatography, with a particle size in the range of 30–80 μm and conventional packed column GC. with that of thick film capillaries for obtaining the maximum loadability at a given performance in efficiency and speed of separation. An alternative treatment, discussing the maximum efficiency of the three column types at normalized loadability and speed of separation is given. Known and established relationships describing plate height, loadability, and linear velocity are used to arrive at the said comparisons. The conclusion of the paper indicates a reconsideration of packed column GC for particular types of analyses where large amounts or high concentrations are required in the detection step.
Supercritical‐fluid chromatography: Open columns vs packed columns
Authors: Schoenmakers P. J. 
Published: May 2005

AbstractSupercritical‐fluid chromatography (SFC) may be performed either in open (capillary) columns or in packed columns. Both approaches have been demonstrated numerous times in the literature. In this contribution it will be attempted to discuss some aspects of columns for SFC. Some advantages of both types of columns will be identified. Attention is paid to the stationary phase film thickness, the speed of analysis, and to the maximum number of theoretical plates (effect of column pressure drop). In this brief contribution many questions will be left unanswered and many significant aspects will be left undiscussed, illustrating that much research remains to be done in this area.
Micropreparative system for enrichment of capillary GC effluents
Authors: Nitz S. , Drawert F. , Albrecht M. , Gellert U. 
Published: May 2005

AbstractAn automated system for preparative gas chromatography with capillary columns is described. The effluet from the capillary column is switched to the FID detector or to the traps by means of a Live‐T switching device. The pneumatics is controlled by a microprocessor so that repetitive sampling can be performed over a period of days in order to enrich sufficient amount of material for NMR or other spectroscopic methods. The effluent containing the compounds is collected in glass tubes filled with column packing material (e.g. Chromosorb coated with 3% OV ‐ 101, crosslinked). The trap temperatue can be adjusted from + 20°C to − 80°C, depending on the trapping material and volatility of trapped substances. The analysis of enriched substances or chromatographic fractions can be performed by thermal desorption of the same traps or by solven elution. The recovery of enriched substances is higher than 90%. High capacity and resolution for enrichment of trace components are obtained with the aid of a double column‐double oven system. Examples of such applications are given.
Evaluation of factors affecting pyrolysis in A microfurnace system
Authors: Dawes P. A. , Cumbers M. K. , Hilling P. A. 
Published: May 2005

AbstractA styrene isoprene block copolymer, known as Kraton 1107, is used to study some of the parameters involved in the pyrolysis process. Using a continuous mode microfurnace pyrolysis system interfaced to a capillary gas chromatography system, the effect of pyrolysis temperature and gas flows through the pyrolysis chamber were studied. Comparisons in sample introduction methods were made. Introducing the sample in solution, rather than conventional solid sample introduction, was found to offer some advantages.
A technique for coating capillary columns with a very thick film of cross‐linked stationary phase
Authors: Blomberg S. , Roeraade J. 
Published: May 2005

AbstractA method for preparation of capillary columns and traps with a very thick film (up to 100 μm) of stationary phase is described. The principle of this method is based on an immediate fixation of a film of prepolymer, formed during dynamic coating. Thus, the development of film irregularities, such as are caused by Rayleigh instability is avoided. Fixation of the film is conveniently accomplished by heat‐accelerated crosslinking as was demonstrated in this work, where a commercially available silicone prepolymer (Sylgard 184, Dow Corning) was employed.The low phase ratio columns which thus can be prepared are interesting both in chromatography with dense mobile phases and as enrichment devices. Examples of the latter application are shown, where trace organic components from air and water were concentrated.
Splitless injection–development and state of the art. Including a comparison of matrix (“dirt”) effects in conventional and PTV splitless injection
Authors: Grob K. , Läubli Th. , Brechbühler B. 
Published: May 2005

AbstractKurt Grob introduced splitless injection in 1969. He elaborated most of the working guidelines including the techniques required for reconcentrating the broad intial bands, i.e. the solvent effects and cold trapping. He also designed a vaporizing injector suited for splitless injection. Nevertheless, splitless injection is still often carried out using inappropriate conditions, and many of today's vaporizing injectors are not suited for splitless injection. No autosampler is available that introduces the sample at the appropriate position. Conventional splitless injection is compared to PTV splitless injection for the range of samples that cannot be handled by the anyway superior oncolumn injection, i.e. sample with high loads of involatile byproducts. There is a clear preference for PTV splitless injection as matrix effects observed in conventional splitless injection were found to be substantially reduced or even eliminated.
Fast‐cycle trace analysis of dioxin in flue gas. Monitoring of the incineration of dioxin‐containing waste from seveso
Authors: Blum W. , Szelagiewicz M. 
Published: May 2005

AbstractThe fast trace analysis method used to monitor 2,3,7,8‐TCDD in stack gas during the incineration of the waste from Seveso is described. The sampling of volatile organic compounds from flue gases, distributed between all three aggregation states, is based on a micromethod developed for the trace analysis of water using a specially dimensioned adsorptive charcoal filter (1.5 mg charcoal). In conjunction with subsequent GC/MS measurements the rapid “fast cycle trace analysis” ensured specific 2,3,7,8‐TCDD detection down to 100 pg per m3 flue gas in cycle times of about 1–2 hours.
GC/MS characterization of urinary metabolites of doxylamine succinate: Identification of the aglycones formed from intestinal microflora metabolism of the polar glucuronide metabolites
Authors: Branscomb C. J. , Holder C. L. , Korfmacher W. A. , Cerniglia C. E. , Rushing L. G. 
Published: May 2005

AbstractThis study describes the use of high performance liquid chromatography (HPLC) and capillary gas chromatography/mass spectrometry (GC/MS) in the characterization of polar glucuronide conjugates of doxylamine and their subsequent aglycones following deconjugation. Rat urinary extracts which contained doxylamine and both nonconjugated and conjugated doxylamine metabolites, were examined by HPLC before and after incubation with rat intestinal microflora. The subsequent deconjugated urinary metabolites and the nonconjugated products remaining in the urinary extracts were then isolated, acetylated, and assayed by GC/MS. Incubation with the intestinal microflora indicated that anaerobic bacteria were capable of effecting hydrolytic cleavage of these polar O‐glucuronide metabolites of doxylamine and its demethylated products to their subsequent aglycones. GC/MS analysis was performed using a fused silica DB‐5 GC column and was utilized for the identification of these deconjugated metabolites.
Detection of β‐blocking drugs in urine by capillary column gas chromatography‐negative ion chemical ionization mass spectrometry
Authors: Cartoni G. P. , Ciardi M. , Giarrusso A. , Rosati F. 
Published: May 2005

Abstractβ‐Blocking drugs present in commercial pharmaceutical products are determined in present urine of volunteers between 4 and 24 hours after the administration of a therapeutical dose. The drugs are extracted, hydrolysed, derivatized with pentafluoropropionic anhydride, and analyzed by capillary gas chromatography and electron capture detection. Metabolite identification and drug confirmation is by capillary gas chromatography–negative ion chemical ionization mass spectrometry (GC‐NICIMS). This method is very specific and a sensitivity below 1 ng/ml is obtained.
Effects of organic mobile phase modifiers in micellar electrokinetic capillary chromatography
Authors: Gorse J. , Balchunas A. T. , Swaile D. F. , Sepaniak M. J. 
Published: May 2005

AbstractThe addition of 1–20% (v/v) of methanol or acetonitrile as organic modifier to the mobile phase in a micellar electrokinetic capillary chromatographic (MECC) system, containing sodium dodecyl sulfate and a buffer, is shown to extend the elution range and thus increase the peak capacity of a given system. Although the net change in the elution range parameter, to/tmc, is essentially the same for both modifiers, the acetonitrile‐modified system exhibits much faster elution times for the polar and non‐polar test solutes employed in this study. Retention, as measured by the capacity factor, is generally decreased with the increase of an organic modifier, just as in conventional reversed phase chromatography. However, changes in selectivity as a function of the added modifiers are noted among polar and non‐polar solutes as well. The efficiency of these MECC systems is increased with the addition of either organic modifier.
Retention characteristics of volatile compounds on tenax TA
Authors: Maier I. , Fieber M. 
Published: May 2005

AbstractThe chromatographic separation properties of long, thin adsorption tubes enable substance‐specific quantitative enrichment and reduction to be achieved when sampling and thermal desorption are carried out in the same flow direction.The specific retention volumes, and also the breakthrough and peak end volumes, of 69 compounds in the boiling range between‐164 and 126°C and of a relative molecular mass between 16 and 119 were determined at temperatures between 30 and 130°C: normal alkanes, isoalkanes, cycloalkanes, alkenes, polyenes, alkynes, aromatics, ethers, alcohols, aldehydes, ketones, carboxylic acids and their esters, nitroalkanes, O‐heterocycles, S‐heterocycles, chloroalkanes, water, nitrogen monoxide, nitrogen dioxide, carbon dioxide, and sulfur dioxide.The correlation between adsorbent temperature and specific retention volume of these components, presented in the form of diagrams, permits the required quantity of adsorbent to be determined for a given sample volume. Contrary to literature sources, even extremely volatile compounds such as propane, propene, methanol, formaldehyde, formic acid, and chloromethane can be quantitatively retained on Tenax provided the operating conditions are appropriately selected.
Gas chromatographic separations on packed microcolumns using various 10 μm support particles
Authors: Lagesson V. , Newman J. M. 
Published: May 2005

AbstractPacked columns using 10 μm HPLC‐packing materials as supports for various liquid phases have been studied. The glass columns used were 80 mm long (o.d. 3 mm and i.d. 1.5 mm), the amount of solid support in the column being approximately 0.15 g. A. wide variety of separation characteristics were obtained by combining support material of various surface areas, chemically bonded surfaces, applied liquid phases, and various liquid phase loadings. This type of column is also characterized by a very short gas hold‐up time, leading to possibilities for relatively fast separations. Other advantages are high sample loading, high sample capacity, and low operating cost.
Residential wood combustion: A source of atmospheric polycyclic aromatic hydrocarbons
Authors: Guenther F. R. , Chesler S. N. , Gordon G. E. , Zoller W. H. 
Published: May 2005

AbstractSamples were taken of the atmospheric particulate matter over Fairbanks Alaska in the winter of 1985, and from wood stoves burning the major wood types locally available. These samples were then analyzed for polycyclic aromatic hydrocarbon (PAH). A PAH emission profile was determined from the wood stove samples and applied to the atmospheric samples to determine the residential wood combustion contribution to the local atmospheric particulate burden. Emission profiles for coal burning and automobile emissions for PAH were also used to estimate their relative contributions.
Techniques and procedures for preparation of aquatic samples for chromatographic analyses
Authors: Onuska F. I. 
Published: May 2005

AbstractThe measurement of low levels of organic compounds in environmental samples presents the researcher with a number of possible pathways to effectively obtain and analyze samples. Numerous sampling methods, sample preparation techniques, and extraction procedures are available. A number of different approaches to sampling strategy, isolation, concentration, cleanup and fractionation will be discussed.Objectives for collecting environmental samples differ from those for many other types of samples because reliable measurements at very low levels are frequently required. Often, specific analytes need to be measured at the μg/kg and even ng/kg levels in complex matrices. Advances in analytical methodology continue to lower the levels at which reliable measurements can be made. At these levels, many factors that are of little or no concern in other analytical measurements are of critical importance in influencing the outcome and reliability of environmental analyses.Analytical measurements are used for determining the composition and the quantities of analytes in the defined system at various concentration levels. Environmental analytical measurements provide data about the transportation and transformation of an environmental contraminant and for determination of its concentration in a sample.