bluuebunny/crossref_metadata_2025_split huggingface dataset:
Determination of midazolam and its major hydroxy metabolite in plasma by gas liquid chromatography. Application to a pharmacokinetic study
Authors: Coassolo P. , Aubert C. , Sumirtapura Y. , Cano J. P. 
Published: May 2005

AbstractA sensitive gas liquid chromatographic (GLC) assay was developed for plasma determinations of 8‐chloro‐6‐(2′ ‐fluorophenyl)‐1‐methyl‐4H‐imidazo[1,5 α][1,4]benzodiazepine (compound I) and its hydroxymethylimidazo metabolite (compound II). The internal standards used were 8‐chloro‐6‐(2′ ‐chlorophenyl)‐1 ‐methyl‐4H‐imidazo[1,5 α][1,4]benzodiazepine (compound VI) and 7‐chloro‐5‐(2′ ‐fluorophenyl)‐1, 3‐dihydro‐1‐(hydroxyethyl)‐2H‐1,4‐benzodiazepin‐2‐one (compound VII) for compounds I and II, respectively. Following extraction, and silylation for compound II, compounds I and II were analyzed by GLC using a glass column packed with 5% OV‐101 on Gas‐Chrom Q, and a 63Ni electron‐capture detector. The GLC method was validated by a CI‐GC/MS technique. The detection limit of the assay is approximately 4–5 ng/ml for compound I and 3 ng/ml for compound II. The method was used in comparative pharmacokinetic studies of the distribution of the two compounds in arterial and venous blood.
Qualitative evaluation of aromatic herbs by direct headspace GC analysis. Applications of the method and comparison with the traditional analysis of essential oils
Authors: Chialva F. , Gabri G. , Liddle P. A. P. , Ulian F. 
Published: May 2005

AbstractGC headspace analyses of various aromatizing herbs have been compared with those relating to the essential oils, obtained by steam distillation, of the same plants. In this way it was possible to establish the most significant differences between the composition of a herb flavor and that of its essential oil. In particular, we observed some very volatile compounds in the headspace samples which were absent from the essential oil; these components may make an important contribution to the herb flavor. The identification of these substances is still in progress.
Applications of heart cutting from packed to capillary columns
Authors: Phillips R. J. , Knauss K. A. , Freeman R. R. 
Published: May 2005

AbstractThe power of capillary gas chromatography can be enhanced by selective fractionation of the sample. One way of doing this is heart cutting from a packed gas chromatographic column. This paper describes modification of a commercial instrument for such separations. Components of the system include an automated Deans switch and an electrically heated trap. The benefits of this arrangement are illustrated with chromatograms of naphtha, urinary aromatic acids, and wine volatiles.
Trace analysis of halocarbons in water; Direct aqueous injection with electron capture detection
Authors: Grob K. , Habich A. 
Published: May 2005

AbstractInterest in monitoring halogenated organics in drinking water and natural surface and ground water in the low ppb range continues to grow. There is a tendency to include still more volatile halocarbons, the trace determination of which is known to be rather demanding. This prompted us to re‐examine the feasibility of large‐volume direct aqueous injection onto capillary columns, coupled with ECD. A primary problem was to avoid simultaneous elution of water with halocarbons, since water suppresses the ground current of the ECD. The following measures contributed to the solution of this problem.Apolar, extremely inert, columns are required to elute water completely, and even before very light halocarbons. Their coatings have to be far thicker (≈︁ 5 mUm) than commonly employed thick films since they must permit isothermal analysis at a column temperature around 100°C in order to ensure rapid and complete elution of water. Finally, it is essential that sampling be carried out on‐column for two reasons: diffusion of water vapor in the injector, resulting in delayed elution, is then eliminated, and peak distortion during splitless injection is avoided.Although we now know that persilylated columns with immobilized coatings withstand routine water injections, more longterm experience is needed to provide detailed recommendations for the handling of these columns.
Dynamic leaching of sodium‐glass capillary columns
Authors: Venema A. , Sukkel J. T. , Kampstra N. 
Published: May 2005

AbstractIt is well known that removal of metal ions from the glass surface greatly improves both the thermal stability and the adsorption characteristics of glass capillary columns. Usually metal ions are removed from a glass surface by acid leaching; in particular, the static leaching procedure with hydrochloric acid is used very often for the preparation of glass capillary columns. This paper discusses the results of an investigation into dynamic leaching. Special attention is paid to those factors which affect the adsorption properties of the leached surface. The importance of the non‐specific adsorptivity of the capillary surface due to changes of surface properties induced by the leaching process is pointed out.
Heliflex chirasil‐Val; GC of amino acid enantiomers
Authors: Abe I. , Kuramoto S. , Musha S. 
Published: May 2005

AbstractHeliflex Chirasil‐Val, a modified form of the original Chirasil‐Val phase coated on fused silica capillary, has been investigated with regard to its resolution efficiency and the separation profile for various enantiomeric derivatives of amino acid. The best results could be obtained with TFA‐Et derivatives by reason of the relatively low column temperature required.
Organic micropollutants in the sewage from a phenoxyalkanoic acid production plant after biological treatment in a municipal trickling filters plant
Authors: Folke Jens 
Published: May 2005

AbstractThe environmentally hazardous organic substances in the waste water from the manufacture of chlorophenoxyalkanoic acids have been identified and semiquantified before and after passing through a biological treatment plant for municipal sewage, the secondary effluent of which is discharged into a marine ecosystem. The organics belong to three groups: (i) chlorophenols; (ii) chlorophenoxyalkanoic acids; and (iii) chlorinated neutrals. The removal of chlorophenols and phenoxyalkanoic acids was shown to be good, with a 90% overall reduction of chlorinated substances in the sewage passing through the treatment plant. The lowest reduction occurred for the polychlorinated compounds. Two chlorobenzofurans among the chlorinated neutrals were preliminarily identified.
HPLC, mass spectrometry, and LC/MS of gossypol and its derivatives
Authors: Martlin S. A. , Zhou R. H. , Games D. E. , Jones A. , Ramsey E. D. 
Published: May 2005

AbstractConditions are reported for the reverse‐phase HPLC analysis of gossypol and of some of its derivatives, including anhydrogossypol, gossypolone, gossypol hexaacetate, and Schiff's base derivatives. It is shown that field desorption (FD) and chemical ionization (CI) mass spectrometry have advantages over electron impact (EI) mass spectrometry for the characterization of these compounds and that combined high‐performance liquid chromatography/mass spectrometry (LC/MS), especially when used in the CI mode, is particularly effective.
Multilayer effects in liquid adsorption chromatography with mixed mobile phases
Authors: Borówko M. , Jaroniec M. 
Published: May 2005

AbstractThis paper describes the theory of liquid adsorption chromatography (LSC) with mixed mobile phase, involving formation of multilayer surface phases. An equation describing the dependence of the capacity ratio upon the mobile phase composition is derived and theoretical curves illustrating the same dependence are calculated accordingly by assuming different thicknesses of the surface phase.
The role of column technology in capillary gas chromatography
Authors: Grob K. 
Published: May 2005

AbstractAfter having witnessed, over a period of more than 20 years, the extremely difficult early development of capillary gas chromatography, the growth of scientific understandign, and finally its sudden blossoming into a commonly accepted technique, the author is confronted with a dichotomy. On the one hand, there are the dramatic advances in the fields of column preparation, and of sampling techniques. Implementation of these advances should logically result in correspondingly drastic progress in the average quality of application work in drastic progress in the average quality of application work in capillary gas chromatography. On the other hand, however, such progress is lacking. The greater the practical potential, the smaller the fractionm of that potential which is practically exploited. The reason is that most users interpret te recent advances as exempting them from their obligation to know and think about the many details of practical work, and to attempt standardized work with standard columns and techniques. Standardization of routine work is beneficial, provided the standards are optimized‐a condition which all too often remains unfulfilled. Research work, performed in a realm of ever new and unknown conditions, is of poor quality when done by standardized means. Since the most critical part of optimization is column selection, the capillary column must be mastered as a familiar tool in the hands of the investigator. This is hardly possible in the absence of any direct contact with column technology.
Analysis of gases containing inorganic compounds and light hydrocarbons on fused‐silica open‐tubular columns prepared with a thick liquid phase film
Authors: Palo R. T. , Walters J. D. , March E. W. , Ettre L. S. 
Published: May 2005

AbstractCapillary columns having a thick liquid phase film and a low phase ratio permit the separation of low molecular mass compounds which would have a very small capacity factor on columns with a classical thin film. At the same time, the increased sample capacity allows conventional hot‐wire thermal conductivity detectors to be used with such columns. The analysis of natural and refinery gases, containing both inorganic compounds and light (C1C7) hydrocarbons, utilizing a combination of hot‐wire and flame ionization detectors, is demonstrated.
The optimized separation of aromatic carboxylic acids by HPLC
Authors: Patel B. , Purnell J. H. , Wellington C. A. 
Published: May 2005

AbstractThe optimization of the separation of eight aromatic carboxylic acids, using Hypersil SAS and MOS reverse phase columns, with respect to eluent (methanol : water) composition, pH, and temperature, is described. Window diagram techniques are used and the pH of the aqueous buffer and elution temperature are shown to be more critical than eluent composition.
Optimization of capillary parameters for gas chromatography
Authors: Ogan K. , Scott R. P. W. 
Published: May 2005

AbstractAn HETP equation for the capillary column is developed that takes into account the dependence of gaseous diffusion on pressure, the compressibility of the mobile phase, together with the unique relationship between mobile phase velocity, and the resistance to mass transfer in the stationary phase. The equation is used to develop a procedure for column optimization and expressions are derived that allow the optimum column radius and optimum column length to be calculated for a given fixed inlet pressure. It is shown that fast, simple separations are optimally achieved using relatively short small diameter columns. Conversely, optimum performance for the separation of complex mixtures requiring higher efficiencies requires the use of long columns with relatively large diameters.
Determination of nitrated‐polyaromatic hydrocarbons (nitro‐PAHs) in environmental samples by high resolution chromatographic techniques
Authors: Liberti A. , Ciccioli P. , Cecinato A. , Brancaleoni E. , Di Palo C. 
Published: May 2005

AbstractAn analytical procedure is described for the fractionation of organic compounds present in environmental samples and the determination of nitro polyaromatic hydrocarbons (nitro‐PAHs). Both low and high resolution liquid chromatography are employed for the prefractionation of the soluble organic fraction (SOF) extracted from particulate matter or gaseous pollutants collected on adsorption traps. High resolution gas chromatography is used to analyze four fractions containing alkanes, PAHs, nitro‐PAHs, and other polar PAHs. Nitrogen‐containing species are separated by GC and detected specifically using an alkali flame (NPD) detector. Flame ionization (FID) detection, GC‐MS of positive ions, and negative ion chemical ionization MS of the whole fraction is used for the identification and quantitation of the various components. The composition of SOF extracted from particulate matter emitted from diesel exhausts is elucidated and a large number of nitro‐PAHs identified by the combination of the various techniques.
Enantiomeric separation of halocarboxylic acids by capillary gas chromatography
Authors: Koch E. , Nicholson G. J. , Bayer E. 
Published: May 2005

AbstractThe direct determination of the enantiomeric purity of halocarboxylic acids is described. The method used involves gas chromatographic separation of the corresponding tert‐butylamides on deactivated glass or fused‐silica capillaries coated with Chirasil‐Val. Both the influence of the amide moiety on enantiomeric resolution and tailing, and the racemization during formation of the amide derivatives were studied.
The determination of serum retinol by high performance liquid chromatography
Authors: Woollard G. A. , Woollard D. C. 
Published: May 2005

AbstractA method for the quantitation of retinol in serum by normal phase high performance liquid chromatography is described. The mobile phase consists of a hexane/diethylether/methanol mixture with spectrophotometric detection. The sample preparation is similar to that described by other authors and involves protein precipitation followed by extraction and direct injection onto the chromatograph. Adequate sensitivity is achieved using 200 μl samples. The internal standard chosen is α‐naphthol because of its spectral similarities to retinol and its greater stability than the commonly used retinyl esters. The method has been successfully applied to the clinical evaluation of a number of malabsorption syndromes for which it is preferred to the measurement of total carotenoids.
Quantitative determination of phospholipids in mitochondria using HPTLC and fluorimetric assay in situ
Authors: Wollbeck D. , Kleist E. v. , Elmadfa I. , Funk W. 
Published: May 2005

AbstractA method is described for quantitative determination of phospholipids of mitochondria following one‐dimensional thin‐layer chromatography without previous elution. Using high performance thin‐layer chromatography (HPTLC) and an in situ fluorescence technique, the time needed for quantitative determination is relatively short. As the method is rather sensitive, small amounts of the extracts can be applied (about 200 ng of total phospholipids per spot). The reproducibility for the phospholipid fractions determined was in the range of 8–17%. The procedure was tested with lipid extracts of rat liver mitochondria. The method allows the determination of cardiolipin, phosphatidyl ethanolamine, phosphatidyl inositol, phosphatidyl choline, and sphingomyelin.
Gas chromatographic separation of sugars by on‐column injection on glass capillary columns
Authors: Traitler H. , Del Vedovo S. , Schweizer T. F. 
Published: May 2005

AbstractSugars were separated gas chromatographically on short apolar glass capillary columns by using cold, on‐column injection (OCI) techniques. After silylation, oligomers up to the hexasaccharides could be efficiently separated in resonable retention times. Response factors of silylated sugars were determined as a function of varying sample amounts and concentrations. The optimum injection amount was found to be 1 μl in heptane as solvent.
Construction and application of a cold on‐column injection system for capillary gas chromatography
Authors: Arrendale R. F. , Chortyk O. T. 
Published: May 2005

AbstractA cold on‐column injection system for capillary gas chromatography (GC) applications was constructed. It was based upon a conventional split/splitless capillary GC inlet, which in turn was a modification of a conventional packed GC column inlet. The heart of the laboratory constructed cold on‐column inlet design was a disposable pyrex micro‐sampling pipet, which functioned as a needle guide for sample injection. The sample was injected through a traditional GC septum. Construction of the injection system is described and applications are illustrated by separations of a variety of complex mixtures.
Non‐linear effects of TMS capping on dimethyloctyl HPLC stationary phases
Authors: Tomellini S. A. , Hsu Shih‐Hsien , Fazio S. D. , Hartwick R. A. 
Published: May 2005

AbstractCo‐bonding ligands on the same support to produce “blended” HPLC stationary phases is most commonly carried out in the form of capped reversed‐phase materials. Non‐additive retention properties were observed over a range of trimethylsilane/dimethyloctylsilane ratios. In addition, the increase in retention per mole of bonded trimethylsilane was greatest at the highest dimethyloctylsilane coverages.
Direct determination of the phenanthrene and methylphenanthrene isomer distribution in crude oils by multidimensional capillary GC
Authors: Schomburg G. , Weeke F. , Schaefer R. G. 
Published: May 2005

AbstractThe methylphenanthrene index (MPI) [1,2] which was recognized as suitable for the assessment of the “thermal” history of sedimentary organic matter, can be determined directly i.e. without preceding LC group separations by application of multi‐dimensional GC in capillary columns. A GC double oven instrument (Siemens Sichromat 2) equipped with a “live switching” coupling piece was used for the necessary measurements.
Capillary zone electrophoresis: Effect of physical parameters on separation efficiency and quantitation
Authors: Lukacs K. D. , Jorgenson J. W. 
Published: May 2005

AbstractSeparation efficiency in capillary zone electrophoresis was examined as a function of capillary length and diameter as well as solute concentration for a borosilicate glass capillary/phosphate buffer system. Electroosmotic flow coefficients in borosilicate, fused silica, and teflon capillaries were measured over the useful operating pH range of 3–8 at constant applied power (0.333 W). Sample introduction by a simple, low‐dispersion electromigration method was found to be a reliable procedure for solute quantitation.
Quantitative gas chromatography using a new automated derivatizer
Authors: Frank H. , Gerhardt J. , Nicholson G. J. 
Published: May 2005

AbstractIn the gas chromatographic analysis of complex biological samples, the most time‐consuming and error‐prone steps are the pretreatment required for isolation and purification of the compounds of interest and, for most analytes, the derivatization to chemically and thermally stable compounds with high volatility. These wet‐chemical steps are usually carried out manually, and for routine analysis of large numbers of samples they are often rate‐limiting. A dedicated automated derivatizer has been constructed, the employment of which significantly reduces the time required for manual labor and increases the reproducibility of derivatization and hence the accuracy of analysis.
Capillary GC of triglycerides in fats and oils using a high temperature phenylmethylsilicone stationary phase, part I
Authors: Geeraert E. , Sandra P. 
Published: May 2005

AbstractThe analysis of triglycerides on FSOT columns coated with a phenylmethylsilicone gum opens up new perspectives in fat and oil characterization. On phenylmethylsilicone, besides a “carbon number” or CN separation, the triglycerides are also separated according to the different combinations of saturated and unsaturated fatty acids in the triglycerides.
Application of capillary gas chromatography with electron capture detection and split‐splitless injection to the evaluation of volatile halogenated hydrocarbon removal using hydrogen peroxide after break‐point chlorination in drinking water treatment
Authors: Peruzzi P. , Cursi D. , Griffini O. 
Published: May 2005

AbstractIn this paper we report a way to evaluate the removal of volatile halogenated hydrocarbons formed after break‐point chlorination in the Arno river raw water at the Mantignano Utility, Florence, Italy, following dechlorination by hydrogen peroxide. The removal evaluation is performed by GC‐ECD on fused silica capillary columns with split‐splitless injection on n‐pentane extracts and by other analytical techniques such as UV254 absorption, TOC and TOX. Both laboratory and pilot plant data on Arno river raw water are reported and discussed.
Interlaboratory studies of the determination of selected chlorobiphenyl congeners with capillary gas chromatography using splitless‐ and on‐column injection techniques
Authors: Tuinstra L. G. M. Th. , Roos A. H. , Griepink B. , Wells D. E. 
Published: May 2005

AbstractThe Community Bureau of Reference has organized a collaborative interlaboratory project to improve the analytical protocol for some specific chlorobiphenyls (CBs) within the European Community (EC). A series of test procedures were prescribed to optimize the gas chromatographic conditions for splitless and on‐column injection, which substantially improved the quality of data. Important parameters included the initial column and injector temperatures and the choice of the polarity of the stationary phase. In a study with cleaned eel‐fat extracts, coefficients of variation for reproducibility CV(R) ranging from 11 to 24% at the 0.04–0.3 mg/kg level per CB congener were obtained. No significant difference could be found between splitless‐ and on‐column injection.
Evaluation of smectic biphenylcarboxylate ester liquid‐crystalline polysiloxane stationary phases for capillary column gas chromatography
Authors: Markides K. E. , Chang H‐C. , Schregenberger C. M. , Tarbet B. J. , Bradshaw J. S. , Lee M. L. 
Published: May 2005

AbstractMesomorphic biphenylcarboxylate esters were coupled via flexible aliphatic hydrocarbon spacers to a polysiloxane backbone. The influence of spacer length, percent mesomorphic substitution, and crosslinking of the stationary phase on liquid‐crystalline transition temperatures and on chromatographic performance was investigated. Unique selectivity and good efficiency over a wide temperature range for gum and cross‐linked liquid‐crystalline phases were demonstrated by the separation of various isomeric polycyclic aromatic compounds.
Some applications of capillary gas chromatography in the chemical industry
Authors: van Straten A. J. 
Published: May 2005

AbstractAbout three years ago, fused silica capillary columns were introduced in the Quality Control Laboratory of the Shell refinery/chemical complex at Pernis. In general, long, thick‐film, wide‐bore capillary columns are used together with low split ratios and hydrogen as carrier gas. These conditions enable the analysis of relatively large sample amounts, resulting in low detection limits for the minor components without overloading by the major components, while still maintaining a satisfactory resolution. A number of applications are shown, such as the analysis of complex mixtures, the determination of trace impurities and the analysis of residual volatiles in polymers.