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The concept of stationary-phase optimized liquid chromatography (POPLC) was studied in the context of separation and detection aspects for the determination of explosives. A tailor-made segmented column assembly with three complementary reverse-phase materials enabled the separation of 14 priority target nitroaromatic explosives. This experimental approach resulted in excellent selectivity without using gradient-elution protocols which can considerably deteriorate the performance of electrochemical detection. Consequently, the POPLC separations could be operated under isocratic conditions which were very important for the reliable use of electrochemical detection. Simultaneous UV and dual electrochemical detection resulting in three detection traces was exploited as an additional means for the further enhancement of selectivity in more complex samples.

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.

Zu den klassischen Aufgaben der analytischen Chemie wie Element- und Speziesanalytik kommen im Gefolge der Miniaturisierung immer mehr Anforderungen aus den Nachbardisziplinen. Angesichts der explosionsartigen Vermehrung von Nachweistechniken und Identifizierungsverfahren in Biologie und Molekularbiologie stellt sich die Frage nach einer Neuorientierung und Standortbestimmung der analytischen Chemie immer dringender.

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.

The present study is concerned with the application of nonaqueous capillary electrophoresis (NACE) with electrochemical detection (ED) to the separation and quantitative determination of hydrazine (Hy) and its methyl derivatives. The best performance of NACE-ED was found when using 4 mM sodium acetate/10 mM acetic acid/methanol: acetonitrile = 1:2 as the running buffer, with a bare platinum working electrode set at +1.0 V in an end-column amperometric detection cell. The choice and ratio of suitable solvents for the separation and injection media played an essential role for the performance characteristics of the method. The limits of detection for Hy, methylhydrazine, symmetrical dimethylhydrazine, and unsymmetrical dimethylhydrazine were 5, 2, 12, and 1 ng/mL, respectively. This is between one and two orders of magnitude lower than that achieved by previously reported CE-ED methods in aqueous buffer systems in conjunction with various types of chemically modified electrodes. The practical utility of the new NACE-ED methodology is demonstrated in terms of the determination of traces of Hys in spiked environmental samples containing a wide range of explosives and related compounds.

An analytical scheme was developed for the determination of rare-earth elements and gadolinium diethylenetriaminepentaacetate (Gd-DTPA) in river water by ICP-MS. Since the concentration of Gd-DTPA and the rare-earth elements in river water is often lower than the limits of detection in quadrupole ICP-MS applying pneumatic nebulization, a preconcentration procedure is essential. In this work, the capabilities of countercurrent chromatography (CCC) for preconcentration of REE were investigated. For preconcentration ethylhexylphosphates as stationary phase had been used. Acidified aqueous samples (pH 2) and river water spiked with REE and Gd-DTPA were under study. The procedure was compared with solid phase extraction (SPE) using the same samples and ethylhexylphosphates as stationary phase. The recovery of the light and middle REE was found to be at about 100%, which was found to be more efficient than applying SPE. In contrast, the recovery rates for Yb and Lu were low (and poorly reproducible) using CCC (57% and 73%, respectively) while significant better results were obtained with SPE (89% and 84%, respectively). The recoveries of Gd applying Gd-DTPA were 80 ± 4% in the investigation of river water samples.

Der Trend zu hochmolekularen Analyten scheint Miniaturisierung zu stimulieren. Fragen der klinischen Chemie und der Lebensmittelchemie rucken in den Vordergrund. Apparativ dominiert die Massenspektrometrie, auch als Detektor fur die Flussigchromatographie und die Kapillarelektrophorese. Bei den Trennverfahren spielt die Mehrdimensionalitat eine immer grosere Rolle. Mehr und mehr Publikationen stammen aus dem asiatischen Raum.

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.

Die Erfolgsstory der Gaschromatographie begann zur gleichen Zeit, als die Nachrichten aus Chemie und Technik gegrundet wurden. Diese Trenn- und Analysenmethode hat nicht nur die Kenntnisse uber die Zusammensetzung stofflicher Systeme wie Erdolfraktionen und Umweltproben betrachtlich erweitert, sondern auch der gesamten analytischen Chemie wesentliche Impulse verliehen.

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.

Large-volume injection (LVI) in capillary gas chromatography (CGC) is reviewed, describing imported sample introduction methods, such as programmed temperature vaporisation (PTV), on-column injection, and loop-type injection, as well as some new concepts and trends in LVI. Furthermore, a summary is given of LVI-based applications, including references to more specialised papers.

A review is given dealing with commonly used adsorbent materials in ambient air analysis of volatile organic compounds (VOCs). The adsorbents covered in the paper are selected in consideration of their compatibility with thermal desorption. Initially, we discuss the requirements that an adsorbent should fulfill, and useful parameters for the selection and evaluation of an appropriate material. Then, the most important materials are presented considering their properties, advantages, and drawbacks. A few applications are given, but a complete review of sampling techniques and applications dealing with adsorptive enrichment and thermal desorption is beyond the scope of this paper.

Enzymatische und immunchemische Verfahren sowie Chemo- und Biosensoren prasentiert der abschliesende Teil des Trendberichts zur den wichtigsten Fortschritten in der Analytik der vergangenen zwei Jahre, Teil 1 beginnt auf Seite 455.

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.

Die Analytica in Munchen bietet alle zwei Jahre den richtigen Anlas, uber die Veranderungen und Fortschritte in der Analytischen Chemie zu berichten. Die wichtigsten Stichworte im ersten Teil des Berichtes: Life Sciences, kombinierte Methoden, HTS, Chiptechniken…Ein Nachtrag “Spektroskopie” vervollstandigt im nachsten Monat den Trendbericht.

Systematic investigations were performed to study the dependence of the extraction efficiency of persistent organic pollutants (POPs), including chlorobenzenes, HCH isomers, DDX, PCB congeners, and PAHs, on the accelerated solvent extraction (ASE) operating variables solvent and temperature. Mixed soil samples from two locations with considerable differences in soil properties and contamination in the Leipzig-Halle region (Germany) were used. The objective was to optimize ASE for the extraction of POPs from real soil samples and to improve on the results achieved with Soxhlet extraction (SOX). Solvents with differing polarities were tested. Quadruple and triple determinations were performed on the two soils, respectively, between 20 and 180 degrees C in 20 degrees C steps. All the results were compared with those obtained by SOX, as well as, in some cases during preliminary studies, by ultrasonic extraction (USE). In ASE, the optimum conditions proved to be two extraction steps at 80 and 140 degrees C (average RSD 10.7%) with three static cycles (extraction time 35 min) using toluene as solvent and at a pressure of 15 MPa. Owing to the superior analyte/matrix separation by ASE, in many cases for real soil samples analytical values better by up to 1 order of magnitude or even more were obtained compared to SOX results.

In the context of evaluating air sampling methods, laboratory experiments were performed to investigate the stability of eleven selected low boiling hydrocarbons (e.g. 1,3-butadiene, isoprene) adsorbed on four different carbon based adsorbents. The carbon molecular sieves Carboxen 569, Carboxen 1003, Carbosieve SIII and the graphitized carbon black Carbotrap X were tested. The influence of storage duration on the recovery of the analytes was examined by loading the adsorbent tubes with the test compounds via a sample loop under inert gas. Furthermore, the influence of sampling the hydrocarbons continuously from air on the recovery of the analytes was investigated using a simple experimental set-up providing a flow of synthetic air spiked with the hydrocarbons. Analysis of the loaded adsorbent tubes was performed by thermal desorption and capillary gas chromatography. Losses up to 80% of 1,3-butadiene and isoprene were observed for the carbon molecular sieves, occurring even immediately after the sampling step. In contrast, no significant losses of these reactive constituents were detected for Carbotrap X over a storage time of seven days. The laboratory investigations were confirmed in a field 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.

The use of Solid Phase Microextraction (SPME) for the qualitative and quantitative determination of Linear Alkylbenzenesulfonates (LAS) in waste water samples was investigated. A Carbowax/Templated Resin (CW/¶TPR) coated fiber was directly immersed into influent and effluent samples of a sewage treatment plant (STP). Extraction conditions such as time, pH, ion strength were investigated. The extracted LAS were desorbed with a solvent in a specially designed SPME-LC interface for analysis with HPLC-FLD and Electrospray Ionization Mass Spectrometry (ESI-MS). The combination of SPME with ESI-MS proved to be an alternative technique for the LAS determination in waste water. Linear ranges of the external calibration were found from 0.5–100 ng/mL, with detection limits of 0.5 ng/mL for each individual LAS homologue. The reproducibility of the method is 15% (relative standard deviation).

In reversed phase liquid chromatography, the retention indices of some neutral and acidic explosives and related compounds (nitramines, nitroaromatics, aminoaromatics, and nitrophenols) based on the alkan-2-one, alkyl aryl ketone, and 1-nitroalkane retention index standards have been determined by the application of a new mathematical adaptation method, viz. a multiparametric least-squares regression iterative method. This method was applied to two types of columns. The first group includes six octadecyl-C18 columns with different packing materials and obtained from different manufacturers, while the second group comprises one octyl-C8 column. The retention indices have been extensively studied using either methanol-water or methanol-phosphate buffer mobile phase systems. The calculated multiparametric retention indices values were compared with those obtained by Guardino's, Grobler's, and Kovats' methods. The influences of the concentration of the organic modifier in the mobile phase, aqueous mobile phase pH, and the column packing material on the retention indices of the explosives were also investigated. Good agreement was observed between the retention indices calculated by the use of the four mathematical methods for both neutral and acidic explosives.

In reversed phase liquid chromatography (RP-HPLC), the validity of a multiparametric non-linear least-squares regression iterative method for the determination of the column dead time tM and the regression parameter (slope b), based on the use of alkan-2-ones, alkyl aryl ketones, and 1-nitroalkanes has been evaluated. The determination of tM and b has been extensively studied for two mobile phase systems acetonitrile-water and methanol-water on seven octadecyl-C18 and one octyl C8 analytical columns. The calculated tM and b values were compared with those obtained by Guardino's and Grobler's methods. The influence exerted thereon by the nature of the homologous series, the mobile phase composition, and the packing materials were investigated.

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.

A pyrolysis–GC (Py–GC) method for the quantitative determination of poly(ethylacrylate-methylmethacrylate) (PEAMMA) layers on granules for pharmaceutical use is described. The PEAMMA copolymer layer ensures a sustained release of the active agent after oral intake of the granules by the patient. Because of the substantial influence of the copolymer content on the kinetics of the drug release, a reliable method for the PEAMMA quantification had to be developed. The method includes a pre-treatment step, separating the PEAMMA layer from the granule matrix by its selective dissolution in acetone. Employing the pyrolytically formed monomers ethylacrylate and methylmethacrylate as the target compounds and by means of external calibration, the PEAMMA content of the drug granules was determined with a relative standard deviation of less than 5%. Finally, the Py–GC data obtained from different batches of granule material were compared with the corresponding results of kinetic dissolution tests. For one of six samples investigated a too fast drug release was found to correlate with a too low PEAMMA content.

The capabilities of three extraction techniques (solid-phase microextraction, solid-phase extraction, and liquid-liquid extraction) for the GC trace analysis of di- and tetrachlorinated haloethers in natural water samples were studied. The extraction procedures are described and evaluated with respect to recoveries, precision and detection limits using FID and MS detection. The results are compared. Investigations of the matrix influence show that efficiency and precision of the extraction procedures tested are not significantly influenced by dissolved organic matter in the relevant concentration range. Combined with GC-MS in SIM mode all three extraction techniques are generally suitable for the haloether analysis at ng/L level. However, the precision of solid-phase microextraction (SPME) is poor in this concentration range. Nevertheless, because of several advantages (low time consuming for sample preparation, no employment of solvents) the SPME is favorable for the determination of haloethers ...

Ein segmentiertes Kartuschensaulensystem fur die HPLC optimiert Analysenzeit und Auflosung bei schwierigen Trennaufgaben, etwa bei der Analyse von Explosivstoffen und sprengstofftypischen Verbindungen. Zusatzlich machen ein UV-Detektor und ein elektrochemischer Detektor, kombiniert eingesetzt, die Analysenergebnisse zuverlassiger.

Accelerated solvent extraction (ASE) was used for the simultaneous extraction of semivolatile organic compounds (SOCs) including chlorobenzenes (1,2,3,4-tetra-, penta-, hexachlorobenzene), HCH isomers (α-, β-, γ-, δ-, e-HCH), DDX (p,p‘-DDT, -DDE, -DDD), PCB congeners (28, 52, 101, 138, 153, 180), and PAHs (phenanthrene, anthracene, fluoranthene, pyrene, benzo[a]pyrene) from mosses (Pleurozium schreberi) growing in regional locations (central Germany) and pine needles (Pinus sylvestris L.) from southern Russia (near the Caspian Sea). The results were compared with those obtained by ultrasonic extraction (USE). Using mixed moss samples (thorough cleanup, only minor interference during GC/MSD analysis) from one location mainly served to optimize two parameters, extraction solvent and temperature. The most favorable extraction conditions proved to be n-hexane as the extraction solvent, two temperature stages of 40 and 120 °C, a pressure of 15 MPa, and three static cycles in each case. These conditions were th...

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

This chapter deals with the basic theory of GC. Instead of presenting an in-depth theoretical background, we kept the theory, in particular the equations, to a minimum, restricting it to the most fundamental aspects needed to understand how gas chromatography works. Whenever possible, the practical consequences for the application in the laboratory are discussed. Retention parameters, separation factor, resolution, peak capacity, band broadening including plate theory, as well as van Deemter and Golay equations are discussed. Furthermore, aspects of selecting the optimum gas flow rate are reviewed.

This chapter deals with the chromatographic column. It is often called the heart of the chromatographic system, because the separation takes place here. In the first part, packed, micro-packed and both types of capillary columns (WCOT and PLOT) are introduced and compared. A more detailed examination of the widely used WCOT columns is given. Technical aspects of column production and protocols for column performance characterization, such as the “Grob test,” are discussed. The second part of the chapter deals with the most important liquid and solid stationary phases. Special emphasis is placed on the different polysiloxane phases. Approaches to characterize the polarity of liquid stationary phase, such as the Rohrschneider/McReynolds constants, are highlighted.

For the comprehensive characterization of ambient air concentrations of a broad spectrum of volatile organic compounds (VOCs) an analytical method is described, consisting of adsorptive enrichment, thermal desorption without cryofocusing, and capillary gas chromatographic separation. The method was applied during two-week measuring campaigns in winter and summer 1995, and in the winter of 1996. Long-term sampling was carried out at sampling points in residential areas in the suburbs and near the city center of Leipzig. About 70 VOCs – mainly hydrocarbons from propene to hexadecane – were identified both by GC-MS and chromatographic retention data and quantified after external calibration. Mean values of VOC concentrations obtained during the sampling periods are reported and discussed with regard to the topographical location of the sampling points in the Leipzig area, seasonal variations, and possible emission sources.