bluuebunny/crossref_metadata_2025_split huggingface dataset:
Analysis of classes of compound of environmental concern: I. Nitroaromatic compounds
Authors: Lopez‐Avila Viorica , Benedicto Janet , Baldin Emi , Beckert Werner F. 
Published: May 2005

AbstractThirty five nitroaromatic compounds (currently listed in EPA Method 8091) and 1,4‐naphthoquinone have been separated on DB‐5–DB‐1701 and SPB‐5–SPB‐1701 column pairs, which were in each case connected to an inlet splitter and separate electron capture detectors. Retention times are included for 21 additional compounds evaluated for their suitability as internal standards and/or surrogate compounds for incorporation into Method 8091. Method reproducibility and linearity are discussed, and results are presented for extracts of two real samples spiked with the 35 nitroaromatic compounds and 1,4‐naphthoquinone and analyzed using the dual‐column‐dual‐detector arrangement.
The determination of arsenic and selenium by HPLC combined with alternating current plasma detection and post‐column hydride formation
Authors: Colón Luis A. , Barry Eugene F. 
Published: May 2005

AbstractA helium alternating current plasma detector in combination with HPLC has been evaluated for the determination of arsenic and selenium‐containing compounds after post‐column hydride generation. The construction, operation, and optimization of the system is presented. Detection limits for the compounds under study ranged from 45–60 pg/s. Determination of arsenic and selenium in spiked river water samples has been used to demonstrate the applicability of the technique.
Comparison of two systems for sample preparation and injection by dynamic headspace GC analysis
Authors: Imhof René , Bosset Jacques O. 
Published: May 2005

AbstractThe performance of two commercially available systems employing dynamic headspace techniques for collection, enrichment, and injection of volatile compounds has been compared by GC analysis of test mixtures and dairy products. For technical reasons, it has not been possible to crate identical sorbent materials for both kinds of trap were not available, the most similar adsorbent available were chosen. The total quantity of volatile compounds from a test mixture at the column head was calculated using a theoretical model which enables comparable working conditions to be obtained. Under these circumstances special attention was paid to the repeatability of the data obtained from a test mixture in order to ensure reliable results in quantitative analysis. Significant differences in repeatability between the two systems seemed to originate from their distinctly different technical designs.A qualitative comparison of the systems has been performed using a sample of Swiss cheese. On the basis of the results obtained the systems have been dedicated to different applications in the laboratory of the FAM.
Computer‐aided design and optimization of an on‐line gas chromatographic procedure for the analysis of purgeable compounds in waste water
Authors: Villalobos Richard , Annino Raymond 
Published: May 2005

AbstractThis report describes the application of a computer‐aided column design and optimization program to the analysis of purgeable compounds in waste water. Series‐coupled columns with dissimilar phases can be “selectivity‐tuned” to provide the maximum separation factors, thus facilitating the most rapid analysis. A computer program calculates the column lengths and operating conditions which are required to provide the desired resolution at a specified flow rate.
Automated screening of food and water samples for pesticide residues by means of capillary GC‐MSD using a library of pesticide spectra and macro programming
Authors: Klaffenbach Peter , Stan Hans‐Jürgen 
Published: May 2005

AbstractAutomatic pesticide screening has been performed by use of a macro program to compare mass spectra acquired during GC‐MS with those in designated mass spectral libraries containing a limited number of target compounds. The automated evaluation procedure has enabled fast recognition of pesticides in complex chromatograms.
Micellar electrokinetic chromatography of ionic compounds: The analysis of hop bitter acids
Authors: Vindevogel Johan , Sandra Pat 
Published: May 2005

AbstractSuccessful separation of the six major hop bitter compounds by micellar electrokinetic chromatography depends critically on precise pH control. Any factor which can affect the actual in‐column pH must, therefore, also be carefully controlled: it has been found that temperature‐induced changes of the buffer pH can cause loss of resolution and even reversals in elution order. The pH level at which the effects occur suggests that the pKa values of the analytes are modified by the micellar medium.
Fast, high precision fingerprinting of fatty acids in milk
Authors: Apps Peter J. , Willemse Corné 
Published: May 2005

AbstractA rapid, precise method has been developed for the determination of the fatty acid profile of small samples of milk fat. Lipids are extracted from milk with n‐hexane, triglycerides are trans‐esterified with sodium methoxide, and free fatty acids are esterified with methanolic hydrochloric acid. The methyl esters are separated on a narrow‐bore, 5% phenyl polydimethylsiloxane capillary column. The fatty acid profile is precise: for the various acids the coefficients of variation of peak area are between 6.7% and 9.7%, with a mean of 8.1%, and the coefficients of variation of peak percentage area are between 0.3% and 5.5% with a mean of 1.8%. The nature of the sample preparation procedure does not limit throughout.
Use of literature values of temperature programmed retention indexes in qualitative analysis by isothermal gas chromatography
Authors: Takeda Ichiro 
Published: May 2005

AbstractNumerous reports have appeared on the determination of temperature programmed retention indexes in gas chromatography and although chromatographic variables should be completely consistent with published data if such indexes are to be of use, the reproduction of such rigorous parameters is quite difficult. This report presents an approximate method for using published values of temperature programmed retention indexes in isothermal chromatography.In general, the temperature dependence of the isothermal retention indexes of a number of compounds can be expressed as a series of oblique lines on a plot with retention index as the abscissa and temperature as the ordinate; the elution order of the compounds at a given, isothermal, temperature is then indicated by the points at which the compounds' oblique lines cut the horizontal line corresponding to the temperature of interest.In linear temperature programmed chromatography, the horizontal line representing isothermal operation becomes, to a first approximation, a sloping line with a gradient corresponding to the programming rate: this has been verified experimentally and may be valid over a wide range of temperatures. This line can be used to predict isothermal retention indexes for use in qualitative analysis.
Packed capillary HPLC: An attractive separation technique for small organic molecules
Authors: Bruns Andreas , Polta John 
Published: May 2005

AbstractThe feasibility of using packed capillary HPLC for the analysis of small organic molecules has been demonstrated by three examples: the separation of glucose and sucrose telomers, the separation of the different components of a solvent extraction reagent, and the separation of mono‐, di‐, and trioleins, all of which have been achieved with packed capillary columns of 0.32 mm inner diameter and eluent flow rates of 3 microliters per minute. Application to the analysis of the solvent extraction reagents has shown that this technique can be used as a quantitative tool in just the same way as any conventional HPLC method.The feasibility of a direct packed capillary HPLC – mass spectrometry interface has been demonstrated for the glucose telomer separation; direct coupling is only possible because of the microliter flow rates employed by the technique.
Mixing in the sample loop of the loop‐type interface in coupled LC‐GC
Authors: Grob Konrad , Artho Anna , Le Donne Patrizia 
Published: May 2005

AbstractDuring introduction of an LC fraction into the sample loop of the loop‐type interface mixing occurs between the fraction of interest and the material previously eluted from the LC. Such mixing may not only result in losses of the solute material of interest, but also in contamination of the fraction of interest with material from which it was supposed to have been isolated. Experimental determination of the extent of mixing has led to the conclusion that whereas the effects are negligible under some conditions, in some circumstances the mixing can cause severe problems.
Characterization of Semtex by supercritical fluid extraction and off‐line GC‐ECD and GC‐MS
Authors: Slack Gregory C. , McNair Harold M. , Wasserzug Lou 
Published: May 2005

AbstractResearchers using electron capture for the detection of explosive vapors currently claim the ability to detect the presence of RDX in Semtex – a plastic explosive comprising hexahydro‐1,3,5‐trinitro‐1,3,5‐triazane (RDX) in a matrix of styrene‐butadiene copolymer and hydrocarbon oil. The vapor pressure of RDX at room temperature is 0.006 ppb, and therefore well below the detection limit of electron capture detection (ECD). The positive response generated by ECD is, consequently, not from the presence of RDX, but from some other component.This paper describes the extraction and identification of several compounds in Semtex, along with the determination of which is responsible for the positive response of an ECD‐based detector.From the results of supercritical fluid extraction and off‐line gas chromatography combined with electron capture and mass spectrometric detection, it has been concluded that ethylene glycol dinitrate is the component responsible for the positive ECD response. This conclusion is based on the requirements necessary for ECD detection, i.e. electronegativity, and a sufficient vapor pressure. The other compounds present were eliminated as possible choices because they either can not be detected by an ECD or do not have sufficient vapor pressure under ambient conditions.
Cold on‐column – solvent split injection with a three‐way press‐fit device
Authors: Bicchi Carlo , D'Amato Angela , Semeraro Isabella , Galli Anna , Galli Mario 
Published: May 2005

AbstractIn a previous paper we described the possibilities of cold on‐column – sample split injection achieved by means of an inexpensive and simple three way press‐fit device [1]. The same arrangement is proposed here for cold on‐column – solvent split injection in which specific elimination of the solvent, without loss of any other sample components, is achieved by opening the splitting tube (or better, in this case, the early solvent vapor exit) during solvent elution, and then closing it during elution of the sample's other components.Discrimination between solvent and other sample components is achieved by means of a retention gap, a retaining precolumn, and an early vapor exit.The technique enables both selective enrichment of a sample, in order to record satisfactory mass and infrared spectra of minor components, and injection of large volumes (up to 100 μl) of dilute solutions which cannot be concentrated because of component volatility. Details of the assembly and tuning the system are given, together with some examples.
Analysis of fossil‐fuel fractions by on‐line coupled microcolumn HPLC capillary column GC‐MS
Authors: Welch Kenneth J. , Hoffman Norman E. 
Published: May 2005

AbstractA multidimensional LC‐GC‐MS system was developed and used to analyze complex fossil‐fuel samples. The electron‐acceptor stationary phase, 5 μm 2,4‐dinitrophenylmercaptopropylsilica, was packed into a 0.32‐mm × 350‐mm microcapillary liquid chromatography (μLC) column. Aromatic fractions eluted from the μLC system at 12 μL/min and were diverted to the gas chromatograph mass spectrometer (GC‐MS) by a ten‐port switching valve with 50 and 7.6‐μL loops. Concurrent cosolvent evaporation occurred in a 0.32‐mm × 3‐m precolumn ahead of a 0.25‐mm × 30‐m DB‐5 analytical column. Solvent vapors exited through an open‐split interface. The utility of the μLC‐GC‐MS system was demonstrated through the analyses of solvent refined coal, kerosene, and crude oil.
High resolution capillary gas chromatography of aromatic compounds in multicomponent hydrocarbon mixtures
Authors: Matisová Eva 
Published: May 2005

AbstractThe scope of the principal techniques employed for the analysis of hydrocarbon mixtures is discussed, with emphasis on the analysis of one and two ring aromatic compounds by single column capillary gas chromatography. The paper considers both the column and the selection of the temperature regime (isothermal and temperature programmed). Much space is devoted to the characterization of the compounds by means of retention data.
Separation of highly unsaturated triacylglycerols by reversed phase HPLC with short wavelength UV detection
Authors: Aitzetmüller Kurt , Grönheim Margaretha 
Published: May 2005

AbstractReversed phase HPLC with short wavelength UV detection is a useful alternative to conventional separation systems, with RI detection, for the analysis of the triacylglycerols of highly unsaturated vegetable oils, including γ‐linolenic acid‐containing oils and technical drying oils.γ‐Linolenic acid‐containing triacylglycerols can be identified and separated from their α‐linolenic analogs. The triacylglycerol fingerprints obtained by this technique from many γ‐linolenic acid‐containing oils and technical oils are highly characteristic, as is apparent from chromatograms obtained from the seed oils of Oenothera biennis, Borago officinalis, Ribes nigrum, Primula florindae, and Sapium sebiferum. Characteristic peak area ratios aid the identification of these oils, and estolide peaks are seen in Sapium seed kernel oils.The high detector response for triacylglycerols containing linoleate and/or linolenate residues may present additional advantages, e.g. in the detection of such triacylglycerols in olive oil.
Retention times of fifty one chlorobiphenyl congeners on seven narrow bore capillary columns coated with different stationary phases
Authors: de Boer J. , Dao Q. T. , van Dortmond R. 
Published: May 2005

AbstractRetention times of fifty one important chlorobiphenyl congeners have been determined on seven narrow bore GC columns coated with different stationary phases. The retention times of the chlorobiphenyls relative to tetrachloronaphthalene were plotted for different column combinations; the plots generated can be used to choose an optimum column combination for the multidimensional gas chromatographic separation of the chlorobiphenyls.
The determination of chlorinated biphenyls, chlorinated dibenzodioxins, and chlorinated dibenzofurans by GC‐MS
Authors: Ballschmiter Karlheinz , Bacher Rainer , Mennel Angela , Fischer Regina , Riehle Ulrich , Swerev Max 
Published: May 2005

AbstractHigh resolution gas chromatography, with mass selective detection, has been used for the analysis of PCB on methyl 50 % octyl polysiloxane (SB 50 Octyl), methyl octadecyl polysiloxane, and a smectic polysiloxane (SB Smectic); and for the analysis of polychlorodibenzodioxins and polychlorodibenzofurans with 1 to 8 chlorine substituents on 100 % cyanopropyl siloxane (SP 2331), smectic polysiloxane (SB Smectic), a new polar stationary phase (DB‐Dioxin). The analysis has also been performed by column coupling.
Alysis of the volatile constituents of food by headspace GC‐MS with reversal of the carrier gas flow during sampling
Authors: Barcarolo Robertino , Casson Pierino , Tutta Cristina 
Published: May 2005

AbstractA technique has been developed for performing headspace GC‐MS analysis of volatile components of food, in which the carrier gas flow is reversed during sampling in order to overcome problems caused by the diffusion of substances not retained by the cold trap. Chromatographic profiles of volatile compounds from cheeses, obtained at room temperature, provide confirmation of the validity of the reversed flow technique, and the versatility of the system is evidenced by its successful application to both solid and liquid matrixes: the absence of any discrimination against the various components reveals its efficacy for compounds with a wide range of volatility. Addition of internal standards to the sample enables the use of the technique for quantitative analysis.
Dry‐packed capillary columns for micro HPLC
Authors: Guan Yafeng , Zhou Liangmo , Shang Zhenhua 
Published: May 2005

AbstractA dry‐packing method has been developed which enables the preparation of packed capillary columns for micro HPLC from 250 μm i.d. tubing and 5 μm packing materials. Pressurized gases, such as hydrogen and argon, were used to transport the packing media, and ethanol or methanol were used as discharge agents. By changing the gas pressure, the packing density could be easily adjusted. It was found that, within experimental limits, the higher the packing density, the greater the column efficiency. Comparison between dry‐ and slurrypacked columns showed that the former had greatly improved stability; the efficiency of dry‐packed columns was about the same as, or even better than, that obtained by slurry‐packing.
Signal averaging in gas chromatography
Authors: Ghaoui Labib H. 
Published: May 2005

AbstractEnsemble or signal averaging, and the use of the technique for the solution of some unique problems with minimum sample handling, have previously been reported. The capability of the technique has been evaluated with microbore gas chromatography for the fast handling of a large number of analyses: ca 20–30 replicate injections are easily attainable in a reasonable analysis time. The implementation of the signal averaging technique with other concentration techniques for improving detection limits is also demonstrated.
Aspects of the capillary GC analysis of all‐trans‐ and 13‐cis‐acitretin
Authors: Meyer Evelyne , De Leenheer André P. , Sandra Pat 
Published: May 2005

AbstractThe capillary gas chromatographic (CGC) analysis of the der‐matological drug trans‐acitretin (NeotigasonR) and its cis metabolite is described. Separation of the methyl ester derivatives can be achieved on a 90% biscyanopropylsiloxane phase. The importance of using cold on‐column injection and short, thin film capillary columns is discussed. For patients treated with the prodrug of acitretin, etretinate (TigasonR), i.e. the ethyl ester of Neotigason, three compounds have to be separated. Selectivity tuning is required for successful CGC separation. An alternative can be found in the selectivity of ion monitoring mass spectroscopy. Analysis of plasma samples involves liquid‐liquid extraction, a derivatization step, and HPLC purification.
Evaluation of a radio frequency plasma for oxygen‐selective detection in capillary gas chromatography
Authors: Pedersen‐Bjergaard Stig , Greibrokk Tyge 
Published: May 2005

AbstractA radio frequency plasma detector for capillary GC has been modified for oxygen‐selective detection. Purification of the plasma gas and purging of both ends of the discharge region with helium were crucial to minimizing oxygen background emission from impurities in the plasma. With a pure helium plasma, eluting hydrocarbons released oxygen from the discharge region resulting in interfering signals on the oxygen channel. These interfering signals were efficiently reduced by using a methane‐doped (0. 15%) low power RF plasma (15 W) sustained in a high make‐up flow (150 mL/min). With this plasma, a 103:1 oxygen‐to‐carbon selectivity and a 100 pg oxygen/s detection limit were obtained. The detector was linear over three orders of magnitude. The detection system has been used to screen for oxygenated compounds in two environmental samples.
Determination of polycyclic aromatic sulfur heterocycles (PASH) in diesel fuel by high performance liquid chromatography and photodiode‐array detection
Authors: Bundt Joachim , Herbel Walter , Steinhart Hans 
Published: May 2005

AbstractAn oxidation method (sulfone method) for the determination of polycyclic aromatic sulfur heterocycles (PASH) in diesel fuel is presented. The aromatic fraction of a diesel fuel, isolated by solid phase extraction, is oxidized under controlled conditions with hydrogen peroxide. The oxidation products, mainly methylated dibenzosulfone, are determined and quantified directly, without further clean‐up, by HPLC with photodiode‐array detection.
Fast analysis of oxygen and sulfur compounds in gasoline by GC‐AED
Authors: Quimby Bruce D. , Giarrocco Vincent , McCleary Keith A. 
Published: May 2005

AbstractThis paper describes a method for determining both the total sulfur content and the concentration of oxygenated additives in gasoline by gas chromatography with atomic emission detection (GC‐AED). The AED provides selective detection of oxygen and sulfur compounds. Because the response factors for sulfur and oxygen are largely independent of the type of compound, calibration and determination of total element content are simplified. The use of a 0.1 mm i.d. capillary column enables complete elution of the components of the gasoline in under 10 minutes.
Extending the scope of enantiomer separations on Chirasil‐Dex by GLC: Comparison with permethylated β‐cyclodextrin dissolved in OV‐1701
Authors: Schmalzing Dieter , Jung Martin , Mayer Sabine , Rickert Jan , Schurig Volker 
Published: May 2005

AbstractGLC on polysiloxane‐anchored permethylated β‐cyclodextrin (Chirasil‐Dex) has been used to separate the enantiomers of 106 racemates of different classes of compounds ranging from alkanes to highly polar compounds such as underivatized diols and free acids. Chromatographic data are listed and compared with those obtained by GLC on permethylated β‐cyclodextrin dissolved in OV‐1701.
Coupled LC‐GC‐MS for on‐line clean‐up, separation, and identification of chlorinated polycyclic aromatic hydrocarbons at picogram levels in urban air
Authors: Östman Conny , Nilsson Ulrika 
Published: May 2005

AbstractCoupled liquid chromatography – gas chromatography – mass spectrometry (LC‐GC‐MS) has been applied for on‐line clean up, separation, and identification of chlorinated polycyclic aromatic hydrocarbons (CI‐PAHs). A loop‐type interface was used to couple the liquid chromatograph on‐line with the GC‐MS, and concurrent solvent evaporation was used for sample transfer.A back‐flush technique was used in conjunction with a two‐dimensional column system for isolation of CI‐PAHs and polycyclic aromatic hydrocarbons (PAHs). This fraction was transferred on‐line to the GC and separated on a capillary column. Selective and sensitive detection of CI‐PAHs in the GC eluate was obtained by negative ion chemical ionization (NICI) mass spectrometry and selected ion monitoring (SIM).The combined on‐line system for isolation, separation, and identification showed high precision and accuracy, and demonstrated a linear response from 1 to 1000 pg for chlorinated PAHs. The estimated detection limit was 250 fg for 1‐chloropyrene and 1,6‐dichloropyrene.The technique was demonstrated by analysis of urban air samples. The low detection limit made it possible to use the technique for analysis of personally carried monitoring equipment for measurement of exposure to CI‐PAHs in the work environment.
A study of the aroma profiles of non‐alcohol beer by thermal desorption and GC‐MS
Authors: Kaipainen A. 
Published: May 2005

AbstractThe aroma profiles of different types of low alcohol and non‐alcohol beer have been compared by collection of volatile headspace compounds on Tenax resin and GC‐MS analysis following thermal desorption. Some aroma compounds have been tentatively identified by NBS library search.
Splitless injection of large volumes: Improved carrier gas regulation system
Authors: Grob Konrad , Fröhlich Dieter 
Published: May 2005

AbstractThe classical vaporizing injector has been modified for splitless injection of large volumes: during solvent evaporation in the packed vaporizing chamber, the carrier gas supply is interrupted and the septum purge outlet fully opened. This prevents vapors penetrating the gas regulation system and keeps the pressure increase in the injector to a minimum.