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Some aroma compounds found in alcoholic beverages are characteristic of a certain beverage (i.e. 2,4-decadienoic acid ethyl ester is characteristic of pear spirit and 5-butyltetrahydro-4-methylfuran-2-on “whiskey lactone” is characteristic of aged spirits like whiskey). These substances were detectable in beverages but not in blood samples. The aim of this investigation was to find a sensitive sampling technique for aroma compounds in whole blood samples. This technique may be used in forensic toxicology for examination of drinking claims. The method comprises dynamic headspace sampling using a purge and trap concentrator, followed by quantitative gas chromatography–mass spectrometry (dynamic HS–GC–MS). The influence of sample preparation, trap adsorbents and sample temperature as well as desorption time and purge time on the quality of the analytical results were investigated. The following optimal parameters were determined: stirred and diluted whole blood sample without salt addition, use of Carbotrap C as trap material, sample temperature at 80 °C, desorption time 20 min and purge time 30 min. These optimal parameters were used for the determination of detection limits (LOD). The LOD of aroma compounds by means of dynamic headspace sampling were compared with the results of conventional sampling: the static headspace technique. Limits of detection for the aroma compounds with conventional static headspace GC are in the range 400–10,000 μg L−1. Dynamic headspace–GC was found to be a more sensitive sampling technique for most of the aroma compounds investigated (e.g. C4–C8 ethyl esters, benzoic acid ethyl ester, linalool oxide and 4-ethylguaiacol) with detection limits between 1 and 50 μg L−1, but there were also limits to the sampling of substances with lower volatility like decanoic acid ethyl ester, 2,4-decadienoic acid ethyl ester, eugenol and whiskey lactone with detection limits of about 1,000 μg L−1.

In order to develop a liquid chromatography/electrospray ionisation tandem mass spectrometry (LC/ESI-MS/MS) method for identification and quantification of polar metabolites of explosives using a triple quadrupole system, the mass spectrometric ionisation and fragmentation behaviour of different nitrophenols, nitro- and aminonitrobenzoic acids, nitrotoluenesulfonic acids, and aminonitrotoluenes was investigated. Due to their different molecular structures, the substances concerned showed a very different ionisation efficiency in the ESI process. Interestingly, 2,4-dinitrobenzoic acid yielded no mass signals in the Q1 scan suggesting a thermal decarboxylation in the ion source, whereas the corresponding 3,5-isomer showed a high ionisation yield. Using negative ionisation polarity, carboxylic, phenolic, and sulfonic acid groups were deprotonated resulting in molecular anions, which could be fragmented in a collision cell. A pronounced dependency of the produced fragment ion series on the kind and position of substituents at the nitrobenzene ring (ortho effects) was observed and exploited for the development of substance-specific detection methods in the multiple reaction monitoring mode. In case of benzoic and sulfonic acids, decarboxylation and desulfonation, respectively, were observed as the most frequent fragmentation reactions. Furthermore, besides loss of NO(2), NO fragmentation occurred and preceded a decarbonylation of the benzene ring. The expulsion of the open-shell molecules NO and NO(2) led to a variety of distonic radical anions.

In the area of former ammunition plants, contaminations caused by explosives and their degradation products are of great environmental relevance because of the immediate vicinity of ground- and drinking water reservoirs. Beside the determination of selected explosive-related compounds by means of HPLC with UV detection, a LC-MS-MS coupling utilizing electrospray ionisation was developed, which is particularly suited for the determination of highly polar compounds. Therewith, 12 different explosive-related compounds were identified and quantified on the basis of specific precursor-/ product-ion traces using the high selectivity and sensitivity of multiple reaction monitoring mode (MRM) of a triple quadrupole mass spectrometer. The LC-MS-MS-technique was applied to water samples from the area of a former ammunition plant. In addition to dinitrophenols and aminodinitrotoluenes which could be determined also by HPLC-UV, some highly polar compounds were found in the contaminated water, for example 3,5-dinitrobenzoic acid and 2-amino-4,6-dinitrobenzoic acid. The highest concentrations (14–40 µg L−1) were found for two isomers of dinitrotoluenesulfonic acids. In order to assure the quantitative determination of polar substances in real samples with different composition, external calibration and standard addition method were compared. The presented LC-MS-MS-method is suited for screening and quantification of polar and hydrophilic explosive-related compounds from different classes of substances in a single analytical protocol.

A novel system for sample introduction into a Gas Chromatograph (GC) using an automated in-column pyrolysis device has been developed. The in-column pyrolysis device is suitable for use with any GC or GC-MS system. Solid samples are dissolved or emulsions can be diluted and injected into the system. Because the system is designed for introducing liquid samples, a better control of the injected sample amounts is achieved. This leads to high reproducibility of the peak areas, offering new opportunities for quantitation of polymers or other high molecular weight materials. In addition, a better statistical representation of the material to be analyzed is given if the samples are dissolved in a solvent. The system can be operated both in a normal GC injection mode, and in the pyrolysis mode. As a conventional GC injector working in on-column or Programmed Temperature Vaporization (PTV) injection mode, (without the pyrolysis function), information on the volatile fraction of a sample can be obtained. Once the volatile materials in the sample have been separated, a second analysis on the non-volatile matrix can be performed by initiating the pyrolysis sequence, yielding information on the non-volatile fraction of the sample. Both features, on column or PTV injection mode and in-column pyrolysis can be used separately or in combination. This new technology is expected to be useful for the determination of additives, monomers, solvents and other volatile components in a non volatile matrix, such as polymers, as well as in the characterization of the non-volatile matrix itself, in a single run.

To enable high sample throughput, an automated solid-phase microextraction (SPME) method coupled with GC-MS for the trace analysis of technical nonylphenol, bisphenol A and 17alpha-ethinylestradiol was developed. The extraction performance of different SPME fibre coatings was examined, with polyacrylate proving most suitable. Although study of the extraction time showed that the analytes have not reached equilibrium after 3 h, as a compromise an extraction time of 1 h was applied in all the experiments with detection limits between 0.04 and 1 microg l(-1) for wastewater effluent. The mean reproducibility of the technique is 8% RSD. Carry-over effects are negligible. The linearity of calibration curves ranges over three orders of magnitude. The method was tested for determining the analytes in influents and effluents of constructed wetland plants and in model wastewater used in laboratory experiments.

A new system has been developed for rapid on-line SPE-LC-MS-MS analysis of a wide spectrum of trace level pesticides in drinking and surface water. The system employs a serial arrangement of two different turbulent flow columns (TFC; polymer based column in front, carbon based column back) for rapid extraction (Turbulent flow solid phase extraction; TFSPE) from small sample volumes (10 mL) at high flow rates (5 mL min−1). Purely organic eluent is used for TFC elution, and the effluent is re-mixed with water in a mixing chamber in front of the HPLC column to provide efficient analyte focusing. This methodology allows to use a short monolithic LC column for the following fast on-line LC-APCI-MS-MS analysis. This approach gives quantitative results for nearly 30 pesticide species (triazines, phenyl ureas, organophosphorous pesticides and others) in less than 14 min and, thus, allows considerably increased sample throughput. The method is well reproducible, robust and extremely sensitive achieving detection limits between 0.1 and 1 ng L−1. As the comparison of internal and external calibration methods showed, potential matrix effects on the quality of the results are managed by the method in a very effective manner. Real pesticide concentrations determined in drinking water and surface water samples showed significant temporal variations but were constantly below the concentration limit for individual pollutants of 100 ng L−1.

This review summarizes a presentation on ambient air analysis of volatile organic compounds given at the “Trace enrichment for GC and HPLC analysis” workshop at the ISC'02. Adsorptive enrichment of volatile organic compounds has become an important technique in ambient air analysis. The paper focuses on the use of adsorptive enrichment for sampling volatile organic compounds. Different techniques for sampling and desorption are reviewed and an overview of commonly used adsorbent materials is given. Furthermore, strategies for managing interferences, such as moisture, are discussed.

A rapid and simple method, pyrolysis gas chromatography coupled with mass spectrometric detection (Py-GC-MS), is introduced for qualitative determination of banned aromatic amines released from azo dyes on textiles. Use of Py-GC-MS can reduce absolute analysis time from three hours to thirty minutes, because no sample preparation is necessary. Qualitative determination of banned amines by Py-GC-MS was investigated for three pure azo dyes and six contaminated textile samples consisting of different matrices. Pyrolysates of pure azo dyes were identified as aromatic amines. Banned aromatic amines released from azo dyes could be qualitatively determined for four of six contaminated textile samples by Py-GC-MS.

This work deals with the investigation of the possibilities and limitations using a commercially available software package Drylab for the fast optimisation of running conditions and the prediction of separation and retention times of a mixture consisting of fourteen neutral (nitramines, aminonitroaromatics and nitroaromatics) and six acidic (nitrophenols) explosive-related compounds.

Headspace solid-phase microextraction (HS-SPME) has been successfully applied to the determination of perfume components in scented candle wax, liquid laundry detergent, and fabric softener. Different fiber coatings (100 μm polydimethylsiloxane, 50/30 μm divinylbenzene/Carboxen/polydimethylsiloxane, 70 μm Carbowax/divinylbenzene, and 85 μm polyacrylate) were tested and the extraction conditions were optimized. For most compounds extraction efficiency, reproducibility, and long-term stability were highest for polydimethylsiloxane. The compatibility of SPME with fast gas chromatographic separation was investigated. The speed of conventional gas chromatography was increased by a factor of 2.5, without loss of separation efficiency, simply by reducing the column length and inner diameter and adjusting the separation conditions by use of method translation software. It was demonstrated that SPME is a suitable sample-introduction technique for fast GC if split injection is used.

This work describes methodical studies of thermally assisted hydrolysis and methylation (THM) of fatty acids (FA) and triglycerides comparing different derivatization reagents, such as tetramethylammonium hydroxide (TMAH), tetramethylammonium acetate (TMAAc), trimethylsulfonium hydroxide (TMSH), trimethylphenylamine hydroxide (TMPAH), and (m-trifluoromethylphenyl) trimethylammonium hydroxide (MethPrep 2). The performance of these reagents using different injection techniques, such as pyrolysis, hot split injection, and programmed temperature vaporization (PTV) has been investigated.

Thermally assisted hydrolysis and methylation (THM) provides an interesting alternative to other derivatizing sample preparation techniques because of its simplicity and rapidness. The paper presents THM–GC/MS data obtained from standard compounds (cholesteryl stearate, 2-hydroxypalmitic acid) and several types of wax (candelilla wax, beer wax, lanolin, beeswax) using tetramethylammonium hydroxide (TMAH) as reagent. Application of tetramethylammonium acetate (TMAAc) instead of TMAH enables selective analysis of free fatty acids in the presence of esters. Comparison of the results with those obtained from Py–GC/MS illustrates that THM provides a much higher extent of information. The thermochemolytic behaviour of several wax compounds is discussed. THM yields may differ from compound to compound due to specific thermal and chemical behaviour. While structurally simple wax esters, e.g. cholesteryl stearate, gave very efficient conversion within a wide temperature range between 350 and 600°C, compounds of less thermal stability (e.g. 2-hydroxyfatty acids) yielded substantial amounts of pyrolysis products (aldehydes) even at the lowest temperature applied (350°C). Some phytosterols present in candelilla wax showed less affinity to TMAH and were only partly converted into methyl ethers. Various applications of THM–GC/MS are described: analysis of lipid based leather polish, identification of wax content in spots in ancient Egyptian textiles, profiling of pharmaceutical lanolin batches, characterization of aging processes in lanolin. Fingerprints and characteristic marker compounds were employed for discrimination and identification purposes.

AGC method has been developed for the analysis of tricholoroacetic acid (TCA) in water samples. It entails large-volume injection (LVI) and programmed-temperature vaporization (PTV) of water samples, thermal decarboxylation of TCA to chloroform in the injector, and GC-ECD analysis of the decarboxylation product. Conditions such as final injector temperature, splitless time, and injection volume were optimized. The limit of detection is approximately 0.1 μg L−1 Several real samples were analyzed. The method presented is an easy means of determination of TCA and eliminates sample-preparation steps such as extraction and derivatization.

Laboratory experiments have been performed to examine the potential of adsorptive enrichment thermal desorption and gas chromatography for the analysis of low molecular-weight oxygenated compounds in gaseous samples. The experiments were conducted with test atmospheres containing, for example, acetaldehyde, propionaldehyde, acrolein, methacrolein, and acetone. The suitability of the graphitized carbon blacks Carbotrap X and Carbograph 5 for sampling these compounds was tested. In this context the influence of humidity on the recovery of the analytes and on the storage stability of the loaded adsorbent tubes over a period of seven days under different storage conditions was investigated. Losses of up to 60% propionaldehyde and acrolein were observed for Carbotrap X, even immediately after sampling. In contrast Carbograph 5 seems promising for the sampling of low molecular-weight oxygenated compounds, although with some limitations. The laboratory investigations were proved by use of an interlaboratory experiment.

A new PLOT column (CP-LOWOX) designed specifically for the analysis of oxygenated compounds has been used for the gas chromatographic determination of semi-volatile carbonyl compounds. The separation behavior of the new column was investigated by comparing it with the widely used non-polar polydimethylsiloxane and polar poly(ethylene glycol) columns. The CP-LOWOX column has unique selectivity for aldehydes and ketones enabling a selective separation of these analytes from predominating hydrocarbon matrices. Application of the CP-LOWOX column for the analysis of polar compounds in ambient air is demonstrated. Sampling was performed by adsorptive enrichment coupled with thermal desorption. The suitability of Tenax TA and a multi-bed adsorbent trap Carbotrap C and Carbotrap) was tested for the sampling of semivolatile carbonyl compounds.

THM–GC/MS was applied to the analysis of natural waxes (bleached beeswax, lanolin, yellow carnauba wax). By means of flash heating the wax samples in the presence of tetramethylammonium hydroxide (TMAH) as an alkaline derivatization reagent, the wax constituents, mainly high molecular weight esters, were hydrolyzed and converted into their methyl derivatives. Subsequent GC analysis of the methylation products resulted in chromatograms showing very specific signal patterns for each of the materials investigated. Mass spectrometric detection of the yielded methyl derivatives enabled the identification of more than ninety compounds present in the wax samples, i.e. fatty acids, hydroxy fatty acids, fatty alcohols, diols and sterols, respectively. Additionally to the analysis of real wax samples, several wax-relevant compounds (waxy esters, fatty acids, fatty alcohols) were studied with regard to their methylation behaviour. The investigations show that THM–GC/MS is able to overcome problems that arise from conventional Py–GC analysis of waxes, where thermal fragmentation can lead to rather non-specific pyrolysis products. Therefore, THM–GC/MS is an advantageous technique for the comprehensive analysis of natural waxes.

Three natural waxes (bleached beeswax, lanolin, yellow carnauba wax) were investigated by means of pyrolysis–gas chromatography–mass spectrometry (Py–GC–MS). Pyrograms were obtained showing very characteristic signal patterns. Mass spectrometric detection enabled the structural identification of the pyrolytically formed fragments. For a more detailed investigation of the thermal degradation behaviour of waxy materials, relevant model compounds were selected. Hexadecylpalmitate, cholesterylstearate, heptadecanoic acid and 1-hexacosanol were examined under identical Py–GC–MS conditions. From the resulting product distribution general statements were able to be derived according to the thermal degradation pathways of typical wax constituents. The findings obtained from the model compounds were then applied to the interpretation of the real wax pyrograms. As a result, conclusions according to their origin from corresponding wax constituents were drawn for the majority of pyrolysis products. Thus, the extended potential of the method for the compositional analysis of natural waxes is demonstrated.

The introduction of large sample volumes in capillary gas chromatography using programmed temperature vaporisers (PTV) is reviewed. The development of the different strategies as well as the state of the art are described. As the analytes are normally enriched in the insert in large-volume PTV injection, the quoted papers are subdivided depending on whether the enrichment was carried out from organic solvents, from water or from gaseous media. Furthermore, the possibilities of PTVs for online coupling with sample preparation methods or other separation techniques and their use as thermoreactors are mentioned.

The potential of large-volume PTV injection was studied for the analysis of triazine herbicides in water samples. Direct water injection and in-vial extraction were described and compared. Detection limits were between 0.01–0.02 μg L−1 and relative standard deviations were

The combination of headspace solid-phase microextraction with atomic-emission detection enables highly selective and sensitive determination of itro musk compounds in cosmetic products. Sample preparation is considerably simplified; there is no solvent extraction step. Enrichment is influenced by the type and amount of cosmetic product investigated. The lowest amount giving well detectable peaks is 1 mg musk compound per kg sample. Calibration curves obtained from spiked solutions of selected reference cosmetics in water show very good linearity. Relative standard deviations of peak areas from repeated measurements are usually

A method was developed for the determination of nitrobenzoic acids and nitrophenols as well as of diaminoaromatics and was applied to the analysis of water samples from the former ammunition plant at Elsnig (Saxony, Germany).

The capillary gas chromatographic retention behavior of α-pinene and tricyclene has been investigated on stationary phases of different polarities. On all but one of the columns employed, tricyclene eluted before α-pinene; only permethylated β-cyclodextrins dissolved in moderately polar polisiloxanes gave a reversed elution order. The intermolecular interactions which caused the unexpected retention behavior were investigated in detail, applying methods of computer simulation. To achieve this, we have developed a calculation algorithm on the basis of molecular mechanical optimizations and programmed it in a macro. This makes it possible to systematically investigate a given configuration space in which all the possible interactions can take place. It was shown that permethylated β-cyclodextrin as host molecule for both guest molecules offers an optimum cavity size. As a result the number of energetically favorable contacts between host and guest molecules as well as the strength of the interactions in this stationary phase were larger. As a consequence the elution order, normally only influenced by the vapor pressure of the compounds at a given temperature, was changed. Nonspecific interactions played an especially important role for these kinds of substances.

Electrochemical detection (ED) in the oxidative and reductive mode was applied to the analysis of nitroaromatics, nitramines, aminoaromatics and nitrophenols in groundwater samples from the surroundings of a former ammunition plant. Settings for working potential and eluent composition were optimized in terms of detection limit, linearity and selectivity. The results were compared with those obtained by UV detection and the advantages of combined UV-ED detection for the analysis of complex samples are shown.

A method for the gas chromatographic trace analysis of underivatized nitrophenols in ground-water is presented. Using a highly de-activated separation system a satisfactory precision for their quantitative GC analysis could be achieved by avoiding condensation of the solvent and by fast injection of the sample. The reproducibility of the peak areas of eleven nitrophenols in ethylacetate was 0.992.

α-Campholene and fencholene derivatives are compounds with interesting odour properties, e.g. sandalwood and woody notes. They have one (derived from the initial product, α-pinene) or several stereogenic centres. The stereoisomers of these compounds may have different odour properties; therefore, analysis methods are developed for the complete separation of the diastereomers and enantiomers. It is shown that the alcohols with one stereogenic centre as well as of the esters and ethers of α-campholene and fencholene derivatives with two stereogenic centres can be separated on permethylated α- und β-cyclodextrins dissolved in polysiloxanes. Factors influencing the separation are discussed.

Flumecinol and related compounds can, without derivatization, be separated into their enantiomers by gas chromatography on cyclodextrin phases; permethylated β-cyclodextrin dissolved in OV-1701 can be particularly recommended. Thermodynamic data describing the different intensities of interaction of the individual enantiomers with the stationary phases were determined. The values measured imply different separation mechanisms for the compounds investigated.

The separation of racemic side-chain fluorinated alkylbenzenes and bromofluorinated analogues by capillary gas chromatography using permethylated α, β and γ-cyclodextrins dissolved in polysiloxanes of different polarity as stationary phases is described. The influence of the achiral polysiloxane matrices on the separation of enantiomers is discussed in the light of the results obtained with the different phases. For a part of the tested compounds thermodynamic data are determined which describe the interaction of enantiomers with the stationary phase. The mechanism of separation is discussed on this basis and by comparison with data for structurally similar compounds.

A GC method is described for the determination of pollutants in aqueous samples by direct enrichment out of large sample volumes in a PTV injector. The vaporized water is eliminated through the split vent and the analytes are concentrated on an adsorbent inside the insert of the PTV. For the selection of suitable adsorbents, breakthrough volumes of selected pesticides and nitroaromatics on Tenax TA, Tenax GR, Chemipack C18 and graphitized carbon blacks have been determined by experiment. The determination of the breakthrough volumes was carried out directly in the PTV insert. Tenax TA proved to be the best sorbent with regard to the breakthrough volumes and its inertness to the analytes to be determined. As the result of the investigations, 500 μl of aqueous standard solutions of pesticides and nitroaromatics (concn.=0.02 ... 2 μg/l) were analyzed with an average relative standard deviation of 10%. The procedure was successfully applied for the analysis of real samples.

Needles of the Macedonian Pine,Pinus peuce Griseb., a conifer growing in the Balkan mountains, were extracted by a Likens-Nickerson simultaneous distillation-solvent extraction device. The components of this essential oil were identified by the retention times obtained on two columns differing in polarity and by GC-MS. Because of the complex nature of such plant extracts, a multidimensional GC method for enantiomer analysis, using a non-chiral pre-column and a chiral main column has been developed. The enantiomeric ratios of five monoterpene hydrocarbons were estimated by GC-GC and GC-GC-MS.

Retention indices of 6 selected hydroxy compounds (aliphatic and bicyclic alcohols, phenols) were determined on 2 HP-5 fused-silica, capillary columns with different film thicknesses (0.11 μm and 0.33 μm) at 8 different oven temperatures between 80 and 150°C. For some substances the I-T plot was found to show a minimum which cannot be explained by the common retention-index temperature-dependence in gas-liquid chromatography. This result is discussed in terms of adsorption at the liquid-solid interface of the capillary column.

An indirect GC method is described for the determination of Ethephon in drinking water on the basis of the headspace analysis of the ethylene formed from Ethephon. In order to reach the necessary detection limit, the entire volume of the static headspace distribution is transferred into a cold injection system (CIS). There, the ethylene is adsorbed on Carbosieve SIII at 10°C and, subsequently, desorbed at 300 °C. The water vapour included in the headspace is completely eliminated through the splitting system. By means of this technique, a detection limit of 0.05 μg/l water was reached.

Using achiral stationary phases of different polarity in capillary gas chromatography it is demonstrated that the hydration of 1,2–5,6-dibenzocycloocta-1,5-diene yields five isomers of the tricyclo[10.4.0.04,9]hexadecanes. With highly polar stationary phases all isomers of the tricyclic hexadecanes and the semihydrated products in the mixture were also separated from each other. The chiral isomers were separated on cyclodextrin stationary phase. Moreover, with columns of achiral and chiral phases coupled in series, in a double oven gas chromatograph, it was possible to estimate the configuration of the isomers. The separation of diastereomers on chiral stationary phases is a useful means for structural assignment of isomeric compounds.

A quantitative method for the determination of organic acids in atmospheric particles is developed. The method couples a derivatisation step (thermally assisted hydrolysis and methylation) and a Curie point pyrolyser as a thermal desorption technique and gas chromatography–mass spectrometry (CPP-GC–MS). Among the reagents tested (tetramethylammonium hydroxide (TMAH), tetramethylammonium acetate (TMAAc) and phenyltrimethylammonium hydroxide (TMPAH)), the best performance was found using TMAAc as a derivatisation reagent for the reaction time of 4 s at 510 °C as heating temperature. Calibration was performed for a series of fatty acids (FA), dicarboxylic acids (DCA) and terpenoic acids (TA) under these conditions. Coefficients of determination (R2) were between 0.94 and 0.98. Limits of detection (LOD) were in the nanogram-range between 0.1 and 3.6 ng. The method is applied on atmospheric particle samples to obtain the quantification reproducibility and quantification limits. Reproducibility was determined in terms of relative standard deviations (RSD) for ambient aerosol samples collected by a high-volume-sampler (HVS, RSD = 6–45%, n = 10) and a Berner impactor (BI, RSD = 5–34%, n = 10). Based on 24 h sampling time the developed method enables quantification of all three classes of acids for both sampling techniques. Calibration data and presented volume concentrations are compared with literature data. A comparison with an off-line methylation-GC–MS using BF3 as a derivatisation reagent and capillary electrophoresis coupled mass spectrometry (CE-MS) showed a good agreement. Minimal sample preparation is the main advantage of the developed method. Depending on the sensitivity requirements the present method can be a fast and simple alternative to GC–MS techniques with conventional sample preparation steps for semi-volatile organic acids.

Structure - Chromatographic Retention Relationships of Stereoisomeric Methyl-substituted Isochromanes Retention times of 13 mono-, di- and trimethylsubstituted isochromanes are determined on both polar (PEG) and nonpolar (OV-1) stationary phases and KOVATS retention indices (I) are calculated. The significant retention index differences (ΔI) between stereoisomers (up to 30 units) are discussed with respect to the configurational and conformational arrangement of the substituents. Retention indices determined by gas-solid-chromatograhpy (GSC) on graphitized thermal carbon black (GTCB) complete the research.

After a short survey of the variants of multi-dimensional gas chromatography resulting from the combination of different columns and operating parameters, the possibilities of the use of the retention index concept in systems of series-coupled columns without intermediate trapping for the identification of individual components in complex mixtures are discussed. This technique allows a greater reliability of chromatographic identification by the use of the retention index concept for the simultaneous determination of Kovats retention indices on the two columns, the calculation of isothermal retention indices on the second separation column with temperature-programmed operation of the first column and the predetermination of system retention times of individual components on the basis of known retention indices on either column alone.

The adsorption of moelcules on the nonspecific and nonporous adsorbent graphitized thermal carbon black (GTCB) is mainly determined by their intermolecular dispersion interaction with the flat graphite surface. Since the retention values strongly depend on the geometrical configuration and shape of the investigated molecules and their arrangement on the graphite plane, it is possible to separate compounds with only small differences in their molecular shape on short columns packed with particles of pure or modified GTCB.

For calculating retention ( t R ) times from retention indices in series-coupled column systems with different flow-rates in the individual columns, the dependence of the dead time and of the parameters a and b of the log t R versus carbon number plots for n -alkanes on the pressure of the medium is discussed. It is shown that the intercept a of the log t R versus carbon number plots is composed additively of an easily determinable flow-independent term and a flow-dependent term. On this bases, a method was developed for the precalculation of the retention times of any substances from their retention indices under the condition of selectivity tuning by varying the flow-rates in a system of series-coupled GC columns. The method allows statements on the presence or absence of compounds of interest by comparing calculated and measured system retention times. By repeating the identification algorithm at different pressure settings and, consequentl, flow-rates, the peak shifts expected in selectivity tuning can be pursued on the one hand; on the other, a degree of certainty about the positive identification of compounds can be achieved owing to the feasible avoidance of peak overlapping, which is not possible by means of the classical retention index concept.

In a series-coupled system of two capillary columns with different polarity, a controlled overlapping of sulphur-containing and sulphur-free compounds can be achieved by means of different mid-point pressure settings. By means of this selectivity tuning it is possible to measure exactly the quenching of the flame photometric detector signal for a sulphur compound coeluted with an excess of a sulphur-free compound. With the example of a complex sample it is shown that, with a suitable system of columns, selectivity tuning can give quench-free FPD chromatograms or chromatograms with quench-free regions.

An integrated on-line SPE–HPLC–MS/MS system has been developed for the rapid analysis of various trace level priority pesticides in surface and drinking water. Eleven pesticides were included in this study, with various phenylureas, triazines and organophosphorous species among them. Use of turbulent-flow chromatography columns (TFC, 50×1 mm, 30–50 μm particle size) as extraction cartridges enables fast on-line SPE at high sampling flow-rate (5 ml/min). Polymeric and carbon based TFC columns (Oasis HLB, Cyclone, Hypercarb) allow complete extraction with good recoveries from water volumes up to 50 ml. On-line coupling to HPLC is performed with re-mixing of the organic TFC eluate with water in front of the analytical column to ensure efficient band focussing. For fast HPLC analysis, a short monolithic column is applied in combination with highly selective API–MS/MS detection. Matrix effects on the APCI–MS/MS signal were found to be reduced by the system to an acceptable minimum. Limits of detection, determined for 10-ml samples of river water were in the range between 0.4 and 13 ng/l typically, except trifluralin (approximately 280 ng/l), which is less susceptible to ionization under atmospheric pressure conditions. At an enriched water volume of 10 ml, the whole SPE–HPLC–MS/MS procedure requires less than 14 min. The method was successfully applied to the analysis of drinking and surface water samples taken from several sampling sites around the city of Leipzig, Germany. Concentrations measured (maximum: 16 ng/l simazine in river water) were far below the concentration limits scheduled by law.

The API–MS signal response of several pesticides (atrazine, simazine, isoproturon, diuron, chlorfenvinphos, chlorpyrifos, alachlor, trifluralin) depending on the flow-rate of eluent entering the MS interface was investigated. The investigations were based on API–MS–MS analyses of standard pesticide mixtures in the flow injection mode (FIA) at systematically varied eluent flow-rates using both an ESI interface (Turboionspray) and a heated nebulizer type APCI source. In the result, the individual compounds included in this study showed significant differences in their signal response behaviour depending on the flow-rate of eluent applied. The most hydrophobic compounds among the investigated pesticides (chlorpyrifos and trifluralin) showed drastic losses of sensitivity with increasing eluent flow-rate in both ESI and APCI, while more hydrophilic compounds like atrazine, simazine and isoproturon showed the expected signal response (concentration-sensitive in ESI, mass-flow-sensitive in APCI) at least within a certain range of flow-rates (200–600 μl/min in ESI, 200–2000 μl/min in APCI). These findings lead to the conclusion that application of a programmed HPLC eluent flow-rate may be advantageous to achieve maximum sensitivity of API–MS detection for all pesticides of interest. This is exemplified by the implementation of a flow gradient into an online SPE–HPLC–APCI–MS/MS method for improved analysis of pesticides in drinking water.

The coupling of high-performance liquid chromatography (HPLC) and atmospheric pressure ionisation mass spectrometry (API-MS) seems to be the method of choice if good separation and selective detection of semi-volatile, thermolabile, and polar substances is required. Libraries of mass spectra will make the identification of unknown substances in complex environmental samples easier and more user-friendly. Unfortunately, existing GC-MS libraries are not applicable to HPLC-API-MS analysis. Thus, new and extensive mass spectral libraries were constructed. Several investigations of chromatographic (composition and salt concentration of the eluent) as well as mass spectrometric (orifice voltage) parameters and a few applications of real environmental samples are used to discuss the possibilities and limits of these libraries.

The application of programmed temperature vaporisation (PTV) in capillary gas chromatographic analysis is reviewed. The development of the different strategies as well as the state of the art are described. As the analytes are normally enriched in the PTV insert, the quoted papers are subdivided depending on whether the enrichment was carried out from organic solvents, from water or from gaseous media. Furthermore, the possibilities of PTVs for on-line coupling with sample preparation methods or other separation techniques and their use as thermoreactors are mentioned.

Molecular structure and retention behaviour. V. Calculation of adsorption energies for aromatic hydrocarbons on graphitized carbon black The energies of adsorption are calculated for some aromatic hydrocarbons and methyl-substituted benzenes by use of empirical potential functions. Suggestions about the orientation of adsorbed molecules on the graphite surface are made. It is necessary for explanation of the partly small differences in adsorption energy for aromatic and conjugated systems to include both changes of the energy of non-bonding interactions and the electronic structure. The participation of charge-transfer interactions in adsorption is discussed for compounds of this type.

Molecular structure and retention behaviour. XII. Refention behaviour of alkylnaphthalenes by gas-liquid and by gas-solid chromatography The retention indices of 1-alkyl- and 2-alkylnaphthalenes, of isomeric dimethylnaphthalenes, of some trimethylnaphthalenes and methylazulenes have been determined by gas—liquid chromatography (GLC) on glass capillaries of different polarity (methylsilicone OV-1, Ucon LB 550 X and Ucon 50 HB 280 X polar) and by gas—solid chromatography (GSC) on graphitized thermal carbon black, respectively. The retention within homologous series of straight chain 1-alkyl- and 2-alkylnaphthalenes, of isomeric butylnaphthalenes and dimethylnaphthalenes is discussed by means of homomorphic factors and index differences and compared with corresponding values of alkylbenzenes. The different retention behaviour of the isomeric dimethylnaphthalenes by GLC and by GSC can be described by an incremental approach.

For the study of relationships between retention behaviour and molecular structure in GLC and GSC the retention indices of alkenylbenzenes with 2–6 carbon atoms in a straight or branched side chain and of isotopological alkylbenzenes were determined on capillary columns coated with OV-1 and Ucon LB and on a micropacked column filled with graphitized thermal carbon black. From the values obtained index differences corresponding to the increments of the double bond in the side chain were derived. These differences depend significantly on the structure of the side chain and of the position of the double bond.

Molecular structure and retention behaviour. Retention behaviour of cycloaliphatic hydrocarbons in gas—solid chromatography and in gas—liquid chromatography The retention indices of cycloalkanes, cycloalkenes, and some cycloalkadienes of the ring size C6C13 have been determined on a column packed with graphitized thermal carbon black, and compared with the corresponding data on squalane. The relationships between molecular structure and retention indices as well as homomorphism factors are discussed. According to the different separation principles of gas—solid chromatography and gas—liquid chromatography, respectively, the homomorphism factors are negative on graphitized thermal carbon black, but positive on squalane.

Die Retentionsindices von Alkylbenzolen der C-Zahlen 9 bis 14 wurden bei der GAC an einer mit graphitiertem thermischem Rus gepackten Saule gemessen. Die daraus abgeleiteten Homomorphiefaktoren sind fur Benzolderivate mit mehreren Methylgruppen positiv, fur die ubrigen Alkyl-und Dialkylbenzole negativ. Es werden Zusammenhange zwischen Molekulstruktur und Retention diskutiert und die Ergebnisse mit entsprechenden Resultaten in der GVC verglichen. Die Vorteile dieses Adsorbens zur Trennung von Alkylbenzolen mit verzweigten Seitenketten werden demonstriert.