bluuebunny/crossref_metadata_2025 huggingface dataset:
On‐line solid phase extraction ‐ thermal desorption for introduction of large volumes of aqueous samples into a gas chromatograph
Authors: Vreuls Jolan J. , Th. Brinkman Udo A. , de Jong Gerhardus J. , Grob Konrad , Artho Anna
Published: May 2005

A new approach to the introduction of large aqueous samples into a gas chromatograph, solid phase extraction ‐ thermal desorption, is presented. Carrier gas pushes the sample through a packed liner mounted in a programmed temperature vaporizer; analytes retained by the packing material are thermally desorbed after drying of the adsorbent. The sorption properties and thermal stability of some packing materials have been studied off‐line. Tenax GC®, and octyl‐modified silica silylated with diphenyltetramethyldisilazane to improve its thermal stability, appeared to be suitable materials.

The drying period and the desorption temperature are critical for satisfactory performance of the method. When Tenax GC® is used as packing material, thermal desorption at 250°C for 15 min gives quantitative recovery for methyl esters up to hexacosanoic acid methyl ester. With the silylated octyl‐modified silica, the application range is limited to the methyl esters of decanoic to octadecanoic acids.
A trapping column for the coupling of reversed‐phase liquid chromatography and capillary gas chromatography
Authors: Vreuls Jolan J. , Goudriaan Vincent P. , Th Udo A. , de Jong Gerhardus J.
Published: May 2005

A new technique for coupling reversed‐phase liquid chromatography (RPLC) with gas chromatography is described. A fraction eluting from an RPLC column is trapped on a short column packed with polymeric adsorbent. After the mobile phase has been displaced with water, the analytes are desorbed with ethyl acetate. Following a delay time to enable the water to be flushed to waste, the ethyl acetate containing the analytes is introduced into the gas chromatograph under conditions suitable for partially concurrent solvent evaporation, i.e. below the solvent boiling point and at a rate just exceeding the evaporation rate. Post‐column addition of water to the RPLC eluent helps to prevent breakthrough of compounds which are only modestly retained on the trapping column. The relationship between the capacity factors of the analytes on the trapping column and the required dilution factor is discussed. Polycyclic aromatic hydrocarbons are used as test compounds to study the system.
Enantiomer separation by gas chromatography on cyclodextrin chiral stationary phases
Authors: Keim Wilhelm , Köhnes Angela , Meltzow Wilhelm , Römer Helmut
Published: May 2005

Fused silica capillary columns coated with several alkyl or acyl cyclodextrin derivatives, especially those of α‐ and β‐cyclodextrins, are suitable for the enantiomer separation of a wide variety of volatile compounds of different molecular size and functionality. Positional isomers and more than 250 pairs of optical isomers have been resolved, including chiral hydrocarbons, acetals, ethers, epoxides, carbonates, lactones, esters, acids, ketones, aldehydes, alcohols, halocarbons, and also nitrogen‐and sulfur‐containing compounds.

The physical properties of the cyclodextrin derivatives, even those obtained as viscous fluids, could be improved by dissolving them in polysiloxane liquid phases commonly used for GLC.
Determination of amino acids in the hepatic and brain tissue of the rat by gas chromatography
Authors: Moodie T. M. , van der Westhuizen L. , Labadarios D.
Published: May 2005

A procedure is described for the quantitative determination of amino acids in hepatic and brain tissue samples from the rat. Because the presence of certain matrix components in the tissue material led to interference with chromatographic analysis they were removed by a prechromatographic “clean‐up” step.

Quantitative analysis of amino acids, as their N‐heptafluorobutyryl iso‐butyl ester derivatives, was achieved by high resolution gas chromatography on an apolar fused silica open tubular column. Reproducibility data from the complete procedure are presented; coefficients of variation for arginine and histidine in hepatic tissue varied between 7.1 and 10.1% whereas those for most other amino acids were better than 5%, with a mean recovery of 90%.
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

Thirty 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

A 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

The 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

This 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

Automatic 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

Successful 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

A 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

Numerous 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

The 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

During 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

Researchers 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

In 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

A 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

The 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

Reversed 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

Retention 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

High 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

A 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

A 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

Ensemble 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

The 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

A 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

An 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

This 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

GLC 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

Coupled 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

The 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

The 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.
Determination of mono‐ to tetracyclic aromatic hydrocarbons in lubricating oil
Authors: Paschke Angelika , Herbel Walter , Steinhart Hans , Franke Stephan , Francke Wittko
Published: May 2005

Liquid – liquid extraction with N‐methyl‐2‐pyrrolidone, combined with solid‐phase extraction on silica gel using n‐pentane and dichloromethane as solvents, has been used for the isolation and concentration of the aromatic fraction from lubricating oil.

The identification of individual compounds in this aromatic fraction was performed by capillary gas chromatography–mass spectrometry (CGC‐MS) and by determination of retention indices. Quantitative results were obtained by flame ionization detection (CGC‐FID). Eighty four compounds, predominantly naphthalenes, phenanthrenes, biphenyls, fluorenes, dibenzo‐thiophenes, and their alkylated derivatives, have been identified in a commercial lubricating oil. The total amount of the aromatic fraction did not exceed 0.04 % of the oil.
Optimization of conditions in static headspace GC
Authors: Penton Zelda
Published: May 2005

The precision and sensitivity of head‐space GC can be improved by careful selection of the operating conditions: partitioning in the vapor phase can be promoted by altering the sample matrix; the ratio of the volumes of the gaseous and liquid phases, the sample temperature, the equilibration time, and the effect of sample mixing should also be considered.

Most of the principles covered here can be applied to either manual headspace GC or to headspace GC utilizing an automated sampler.
Determination of polynuclear aromatic hydrocarbons in water samples using large volume on‐column injection capillary gas chromatography
Authors: Morabito Paul L. , McCabe Terry , Hiller Joseph F. , Zakett Don
Published: May 2005

An automated large volume on‐column injection technique for capillary gas chromatography (GC) with solvent divert and heated retention gap technology has been utilized to determine polynuclear aromatic hydrocarbons (PAHs) in samples of industrial plant process water. Injecting large sample volumes on‐column enabled the sample preparation procedure to be simplified and provided a fast, labor‐saving technique for screening water samples. Diverting approximately 95% of the solvent away from the analytical column and the detector enabled chromatography to reflect classical capillary loading and detector conditions.

Simplifications include significant reduction of sample and eluent volumes used during extraction and the elimination of Kuderna‐Danish evaporative concentration. System performance, such as linearity and limit of detection, were evaluated for selected PAHs. Spiked water samples were prepared in the lower μ/L range to determine extraction efficiency. Results are compared with those obtained by a reputable contract laboratory following EPA Method 625.
High performance liquid chromatographic separation of polar and non‐polar chlorophyll pigments from algae using a wide pore polymeric octadecylsilica column
Authors: Garrido José L. , Zapata Manuel
Published: May 2005

A method employing a wide pore polymeric reversed phase column has been developed for the separation of most of the chlorophylls and related compounds previously described as occurring in marine microalgae. The high selectivity toward molecular shape of this kind of stationary phase has enabled compounds of very similar structure, such as chlorophylls c1, c2 and Mg‐divinylpheoporphyrin a5 monomethyl ester, and chlorophyll a and the phytol‐substituted chlorophyll c‐like pigments, which commonly coelute on monomeric bonded phases, to be resolved in a single run. Some of these pigments, formerly thought to be a single compound, have, in fact, been demonstrated to be groups of two or more. The method has been successfully applied to both algal cultures and natural sea water samples. When visible light absorbance detection was used, the method proved suitable for separation of various carotenoids.
What hinders the further development of capillary GC?
Authors: Grob Konrad , Schilling Beat
Published: May 2005

Capillary GC was invented a long time ago – in this respect it is aging – but its potential is still far from being fully exploited and it is still an excellent playground for analysts looking for rewarding subjects. The author laments that there is not more activity in the field, provides some tips and subjects for anyone wishing to make his profession more colorful, and does not agree with managers who believe that “lean analysis”, i.e. execution of recipes without any experimenting with the technique, is cost‐effective. Good analysts somewhat resemble artists in character, but can be highly profitable for a laboratory, provided they are given the background to be creative.
Selective and sensitive detection of organic contaminants in water samples by on‐line trace enrichment–gas chromatography–mass spectrometry
Authors: Bulterman Albert‐J. , Vreuls Jolan J. , Ghijsen Rudy T. , Brinkman Udo A. Th.
Published: May 2005

Liquid chromatographic (LC) type trace enrichment is coupled online with capillary gas chromatography (GC) with mass spectrometric (MS) detection for the analysis of aqueous samples. A volume of 1–10 ml of an aqueous sample is preconcentrated on a trace‐enrichment column packed with a polymeric stationary phase. After cleanup with HPLC‐grade water the precolumn is dried with nitrogen and subsequently desorbed with ethyl acetate. A fraction of 60 μl is introduced on‐line into a diphenyltetramethyldisilazane‐deactivated retention gap under partially concurrent solvent evaporation conditions and using an early solvent vapor exit. The analytes are separated and detected by means of GC–MS. The potential of the LC–GC–MS system for monitoring organic pollutants in river and drinking water is studied. Target analysis is carried out with atrazine and simazine as model compounds; the detection limits achieved under full‐scan and multiple ion detection conditions are 30 pg and 5 pg, respectively. Identification of unknown compounds (non‐target analysis), is demonstrated using a river water sample spiked with 168 pollutants varying in polarity and volatility.
Use of open‐tubular trapping columns for on‐line extraction–capillary gas chromatography of aqueous samples
Authors: Mol Hans G. J. , Janssen Hans‐Gerd , Cramers Carel A.
Published: May 2005

The applicability of open‐tubular trapping columns for on‐line extraction–capillary GC analysis is evaluated. The extraction step involves sorption of the analytes from water into the stationary phase of an open‐tubular column, removal of the water by purging the trap with nitrogen, and desorption of the analytes with an organic solvent. The effect of swelling of the stationary phase with organic solvents on the retention power of the trap is studied. When using pentane or hexane as swelling agent breakthrough volumes of at least 10 ml can easily be obtained for non‐polar compounds. For a number of medium polarity compounds breakthrough volumes of 5 ml can be achieved when chloroform is used as the swelling agent. The required drying time is less than 1 minute. Quantitative desorption requires only 75 μl of organic solvent. Solvent elimination prior to transfer to the GC column is carried out using a PTV injector and a multidimensional GC system. The system is applied for the analyses of river water, urine, and serum samples.
Quantitative aspects of directly coupled supercritical fluid extraction–capillary gas chromatography with a conventional split/splitless injector as interface
Authors: Lou Xianwen , Janssen Hans‐Gerd , Cramers Carel A.
Published: May 2005

The quantitative aspects of on‐line supercritical fluid extractioncapillary gas chromatography (SFE‐GC) with a split/splitless injector as interface were investigated. Special attention was paid to the discrimination behavior and the reproducibility of the split/splitless interface. A simple experimental set‐up is proposed that allows accurate quantitation in on‐line SFE‐split GC. The results obtained in on‐line SFE‐GC compare favorably with those from conventional GC with split injection. Discrimination was found to be absent when working at sufficiently high interface temperatures. Finally, the effects of the carbon dioxide flow rate, interface temperature and split ratio on both discrimination and reproducibility were studied.
Capillary gas chromatography—atomic emission detection: A useful instrumental method in pesticide residue analysis of plant foodstuffs
Authors: Stan Hans‐Jürgen , Linkerhägner Manfred
Published: May 2005

The high selectivity of element‐specific atomic emission detection has proven suitable for screening analysis of plant foodstuffs for pesticide residues by capillary gas chromatography, especially for those foodstuffs which contain high levels of matrix compounds. The elemental composition of a peak can, furthermore, be examined by looking at the partial emission spectra recorded during a GC run. This instrumental feature prevents false positive signal interpretation as a result of high concentration levels of eluting matrix compounds.
Simultaneous hydrothermal decomposition and methylation: High resolution gas chromatography–mass spectrometry for polymer characterization
Authors: Oguri Naoki , Onishi Akira , Uchino Sigeki , Nakahashi Keiji , Yamasaki Nakamichi , Jin Xigao
Published: May 2005

High speed hydrothermal decomposition of some chemically inert condensation polymers in alkaline solutions under near‐critical pressures and temperatures has been investigated by on‐line Curie‐point heating–high resolution GC‐MS. The technique also involves simultaneous methylation with tetramethylammonium hydroxide in a 1 mm i.d. × 20 mm sealed glass capillary. The relative standard deviation for the peak intensity (mol %) resulting from ten replicate measurements of poly(butylene terephthalate) is approximately 3%. This method requires a small amount of sample (ca. 0.1 mg) and provides simple chromatograms, greater structural information, good reproducibility, and rapid reaction (0.5–15 min) without chemical treatment. A brief overview of applications to the characterization of some condensation polymers such as aromatic polyester, polycarbonate, and aliphatic and aromatic polyamide is also described.
An overview of LC–MS interfacing systems with selected applications
Authors: Garcia J. F. , Barceló D.
Published: May 2005

Advantages and limitations are described for the different LC–MS interfacing systems (moving belt; direct liquid introduction; thermospray; atmospheric pressure ionization with heated pneumatic nebulizer, electrospray, or high flow ion spray; particle beam; and continuous flow fast atom bombardment). Some comments are also made about interfacing capillary zone electrophoresis (CZE).

The peculiarities of the various interfaces are described, as are liquid chromatographic requirements prior to mass spectrometry using the different ionization techniques. Selected biological and environmental applications are given.
Element‐selective detection using capillary gas chromatography with atomic emission detection
Authors: Cooke M. , Leathard D. A. , Webster C. , Rogerson V.
Published: May 2005

Capillary GC coupled to an atomic emission detector (AED) provides a powerful new hyphenated technique for the separation and characterization of complex mixtures and compounds. The AED provides simultaneous and truly specific multi‐element detection. The specificity of detection reduces the need for the complex sample pretreatment procedures which are necessary to reduce the interference from co‐eluted substances which is experienced with detectors such as the FID and the ECD. A range of environmentally significant problems has been studied, including PCB analysis, the characterization of the reaction products of a novel waste treatment process, and the profiling of sulfur‐containing species formed by the pyrolysis of various types of coal.
Rapid determination of phytanic acid in human blood serum by selectivity tuning in packed column SFC
Authors: Lembke Peter , Engelhardt Heinz
Published: May 2005

A new packed column SFC method has been developed for the determination of phytanic acid in human blood serum. Because of the low viscosity and high diffusion coefficient of supercritical carbon dioxide, several columns can be connected in series, significantly improving separation. Series connection of columns which differ in their selectivity enables the adjustment of the total selectivity towards the individual separation problem (‘selectivity tuning’). In this instance it was possible, after transesterification into their ethyl esters, to separate all the fatty acids in human blood serum, including phytanic acid, by coupling three columns (silica, amino‐propyl, and RP8) in series.
Enantioselective separations by capillary GC on derivatized cyclodextrins. Part 1: Separation of some racemic 2,2‐dialkyl‐4‐alkoxycarbonyl‐1,3‐dioxolane derivatives on permethylated α‐, β‐ and γ‐cyclodextrins
Authors: Jaques K. , Buda W. M. , Pottie M. , Van der Eycken J. , Vandewalle M. , Venema Arnold , Sandra Pat
Published: May 2005

The enantioseparation of some 2,2‐dialkyl‐4‐alkoxycarbonyl‐1,3‐dioxolane derivatives, which are important intermediates in the total synthesis of a number of biologically active compounds, was studied by means of capillary gas chromatography (CGC). The chromatographic results, obtained on columns coated with permethylated α‐, β‐ and γ‐cyclodextrin respectively, are reported. Out of sixteen compounds, thirteen could be separated with a resolution superior to 1,2. One racemate could not be separated on any of the columns. Considerations concerning the separation mechanism are proposed.
On‐line microwave‐induced helium plasma atomic emission detection for capillary zone electrophoresis
Authors: Liu Yan , Lopez‐Avila Viorica
Published: May 2005

We report a feasibility study on using a microwave‐induced helium plasma atomic emission detector (MIP‐AED) as an on‐line detector in capillary zone electrophoresis (CZE). To couple CZE to MIP‐AED, we used an ion exchange membrane capillary to connect the separation capillary to the interfacing capillary. The outlet end of the interfacing capillary was placed directly in the discharge tube of the MIP‐AED system. The electroosmotic flow generated in the separation capillary carried the analytes and the electrolyte buffer solution through the interfacing capillary into the MIP‐AED discharge tube where the analytes were detected. The performance of the CZE/MIP‐AED system was evaluated with trimethyltin chloride, dimethyltin dichloride, n‐propanol, and 2‐butanone. The preliminary results indicate that the MIP‐AED can be used in CZE to provide element‐specific detection for target analytes.
Capillary gas chromatography combined with high performance liquid chromatography for the structural analysis of olive oil triacylglycerols
Authors: Toschi Tullia Gallina , Christie William W. , Conte Lanfranco S.
Published: May 2005

The triacylglycerol composition of olive oil samples has been determined by stereospecific analysis after partial hydrolysis with ethyl magnesium bromide, derivatization, preparative chiral HPLC, transesterification, and GC quantitation of fatty acid methyl esters. The data obtained for position sn‐2 were compared with those from capillary GC analysis of monoacyl sn‐2‐glycerols after enzymatic lipolysis of triacylglycerols.

The determination of triacylglycerols collected by silver ion HPLC and quantified (as fatty acid methyl esters) by GC, together with direct GC analysis on a polar column, have then furnished a comprehensive picture of the triacylglycerol content of olive oil.
Analysis of sorbitan ester surfactants. Part I: High performance liquid chromatography
Authors: Wang Zhendi , Fingas Merv
Published: May 2005

Sorbitan ester surfactants are very complicated mixtures. An improved and simple reversed phase high performance liquid chroma tographic (HPLC) method employing a C18 column has been developed for the rapid separation of sorbitan ester surfactants and the quantitative determination of the distribution of sorbitan mono‐, di‐, tri‐, and tetraester fractions. The sorbitan ester distribution of the six Span and Arlacel surfactants studied was calculated using relative response factors obtained from analysis of pure glycerides of fatty acids. The effects of mobile phase composition on the accuracy and reliability of the distribution values calculated for the sorbitan esters were investigated.
High resolution gas chromatographic determination of the atmospheric reactivity of engine‐out hydrocarbon emissions from a spark‐ignited engine
Authors: Kaiser Edward W. , Siegl Walter O.
Published: May 2005

The reactivities of engine‐out exhaust hydrocarbon (HC) emissions in photochemical smog formation have been determined for three fuels (isooctane, an aromatic blend, and a gasoline) in a single‐cylinder, spark‐ignited engine. High resolution capillary GC was used to determine the mole fractions of the exhaust hydrocarbon species. Temperature programmed chromatography on a single capillary column was sufficient to separate the major exhaust species. A library of approximately 160 hydrocarbon species was used to identify typically 90–95 % of the HC species present. GC‐MS was used selectively to verify peak assignments.

The effect of engine operating parameters (fuel‐to‐air ratio, spark timing, and speed) on reactivity was examined. Engine operating parameters affect both total emissions [g/mile] and the specific atmospheric reactivity [g ozone/g HC emissions] of these emissions. Changing the operating parameters to control total emissions may not be as effective as expected in controlling the total reactivity [g ozone/mile] of the emissions because the specific reactivity can also change simultaneously. Effects of changes in operating parameters differ significantly as the type of fuel is varied. The ability to measure exhaust hydrocarbon species emissions accurately and quickly will increase in importance as reactivity‐based emissions standards come into widespread use.
Simultaneous determination of volatile aromatic and halogenated hydrocarbons in water and soil by dual‐channel ECD/PID equilibrium headspace analysis
Authors: Kolb Bruno , Bichler Christine , Auer Maria , Voice Thomas C.
Published: May 2005

Volatile aromatic and halogenated hydrocarbons are determined in water and soil samples by equilibrium headspace gas chromatography. Simultaneous analysis is carried out in a dual column/dual detector arrangement with ECD and PID. Their determination in contaminated soil is performed with the same instrumental configuration. However, in contrast to water analysis, an increased sample temperature was found necessary for highly adsorptive soil specimens. At sample temperatures of 95 °C, recoveries near 100% have been found. Both adsorption and desorption processes were found to be strongly time‐dependent.