Hans-Jürgen Stan

Determination of clofibric acid and N-(phenylsulfonyl)-sarcosine in sewage, river and drinking water

Abstract Two polar compounds, the drug metabolite clofibric acid (2-(4)-chlorophenoxy-2-methyl propionic acid) and N-(phenylsulfonyl)-sarcosine, were detected as organic contaminants in groundwater samples from sewage farm areas near Berlin at maximum concentrations of 4 μg/l and 150 μg/l, respectively. Contaminations by these two compounds were also found in most of the drinking water samples collected from the 14 waterworks in the Berlin area. The maximum concentrations in drinking water samples were 270 ng/l for clofibric acid and 105 ng/l for N-(phenylsulfonyl)-sarcosine. The analytical results obtained correlate well with the percentage values of artificial groundwater enrichment and bank filtrate used by any particular water treatment plant in drinking water production. Thus, it can be assumed that both polar contaminants commonly leach into drinking water and are not eliminated by the drinking water treatment used by the Berlin waterworks. Positive findings in screening analyses of surface water sa...

Occurrence and Distribution of Organic Contaminants in the Aquatic System in Berlin. Part III: Determination of Synthetic Musks in Berlin Surface Water Applying Solid-phase Microextraction (SPME) and Gas Chromatography-Mass Spectrometry (GC-MS)

Polycyclic musks and nitro musks were found as environmental pollutants in screening analyses of 30 representative surface water samples collected from rivers, lakes, and canals in Berlin. These synthetic musks, which are used as fragrances in cosmetics, detergents, and other products, are discharged by the municipal sewage treatment plants into Berlinπs surface waters. In particular, the polycyclic musks 1,3,4,6,7,8-hexahydro-4,6,6,7,8,8-hexamethylcyclopenta-(g)-2-benzopyrane (HHCB; Galaxolide®, Abbalide®) and 7-acetyl-1,1,3,4,4,6-hexamethyltetraline (AHTN; Tonalide®, Fixolide®) were found in the receiving surface waters at considerable concentrations up to the μg/L-level. In the Wuhle, a small brook almost totally consisting of sewage effluents, maximum concentrations were 12.5 μg/L for HHCB and 6.8 μg/L for AHTN. Additionally, the polycyclic musk 4-acetyl-1,1-dimethyl-6-tert-butylindane (ADBI; Celestolide®, Crysolide®) and 1-tert-butyl-3,5-dimethyl-2,6-dinitro-4-acetylbenzene (musk ketone) were detected at low concentrations in most of the samples. Two other nitro musks, namely 1,1,3,3,5-pentamethyl-4,6-dinitroindene (musk moskene) and 1-tert-butyl-3,5-dimethyl-2,4,6-trinitrobenzene (musk xylene), were only detected in a single surface water sample. Solid-phase microextraction (SPME) with detection by gas chromatography-mass spectrometry (GC-MS) has proven to be a rapid and reliable tool for the screening of synthetic musks in surface and sewage water samples. Internal calibration with a suitable internal standard enables reproducible quantitation of the analytes down to the low ng/L-level. Vorkommen und Verteilung organischer Kontaminanten im aquatischen System Berlins. Teil III: Bestimmung von synthetischen Moschusverbindungen im Berliner Oberflachenwasser mittels Festphasenmikroextraktion (SPME) und Gaschromatographie-Massenspektrometrie (GC-MS) Polycyclische Moschusverbindungen und Nitromoschusverbindungen, die vor allem fur die Parfumierung von kosmetischen Mitteln und Bedarfsgegenstanden Verwendung finden, werden uber kommunale Abwasser durch Klarwerke in die Berliner Oberflachengewasser eingetragen. Im Rahmen eines Screenings von 30 reprasentativen Oberflachenwasserproben aus Flussen, Seen und Kanalen Berlins wurden insbesondere die polycyclischen Moschusduftstoffe-1,3,4,6,7,8-Hexahydro-4,6,6,7,8,8-hexamethylcyclopenta-(g)-2-benzopyran (HHCB; Galaxolide®, Abbalide®) und 7-Acetyl-1,1,3,4,4,6-hexamethyltetralin (AHTN; Tonalide®, Fixolide®) in Konzentrationen bis in den μg/L-Bereich im Oberflachenwasser detektiert. In der Wuhle, einem kleinen Gewasser, das zu grosen Teilen aus Abwassereinleitungen besteht, wurden maximale Konzentrationen von 12.5 bzw. 6.8 μg/L fur HHCB und AHTN gemessen. Weiterhin wurden die polycyclische Moschusverbindung 4-Acetyl-1,1-dimethyl-6-tert-butylindan (ADBI; Celestolide®, Crysolide®) und die Nitromoschusverbindung 1-tert-Butyl-3,5-dimethyl-2,6-dinitro-4-acetylbenzol (Moschus Keton) in den meisten der Proben gefunden. Zwei weitere Nitromoschusverbindungen, 1,1,3,3,5-Pentamethyl-4,6-dinitroindol (Moschus Mosken) und 1-tert-Butyl-3,5-dimethyl-2,4,6-trinitrobenzol (Moschus Xylol) wurden lediglich in einer Probe gefunden. Die Festphasenmikroextraktion (SPME) erwies sich in Verbindung mit der Kapillargaschromatographie-Massenspektrometrie (GC-MS) als schnelle und zuverlassige Methode fur das Screening von synthetischen Moschusverbindungen in Oberflachen- und Abwasserproben. Die interne Kalibrierung unter Verwendung eines geeigneten internen Standards ermoglichte die reproduzierbare Quantifizierung der Analyten bis in den unteren ng/L-Bereich.

Conversion of linoleic acid hydroperoxide by soybean lipoxygenase in the presence of guaiacol: Identification of the reaction products

Linoleic acid hydroperoxide formed by soybean lipoxygenase was metabolized by the same enzyme in the presence of guaiacol. The products of this reaction included trihydroxyoctadecenoic acids, hydroperoxydihydroxyoctadecenoic acids, hydroxyepoxyoctadecenoic acids, dihydroxyoctadecenoic acids, hydroxyoctadecadienoic acids, and oxooctadecadienoic acids.

Determination of residues of anabolic drugs in meat by gas chromatography-mass spectrometry.

The residues in meat of seven estrogenic drugs used in anabolic preparations for animal production were analysed as trimethylsilyl ethers by electron-impact gas chromatography-mass spectrometry following a simple clean-up procedure. The compounds under investigation were: 17 beta-estradiol,l diethylstilbestrol,l hexestrol, dienestrol, stilbestrol, ethynylestradiol and zeranol. The method includes extractive homogenization of 10 g of meat in tetrahydrofuran, followed by liquid-liquid partition between acetonitrile and hexane and finally a chromatographic purification step on a small silica gel column. Gas chromatography was carried out on a 10-m glass capillary column coated with SE-54 using a temperature program from 100 to 250 degrees C. The capillary column was connected to the ion source by an all-glass open-split interface with a scavenger gas-line. Detection of anabolic residues was performed with selected ion monitoring on intensive ions in the mass region above m/e 400, resulting in a detection limit of 1-5 ppb (10(9)). Quantitative determinations were performed using dodecyl gallate as an internal standard applying the signal ratio of the drug and the standard.

Analysis of Phenoxycarboxylic Acids and Other Acidic Compounds in Tap, Ground, Surface and Sewage Water at the Low ng/1 Level

Abstract Solid-phase extraction with RP-C18 phase has been successfully applied for the determination of more than 30 acidic herbicides and related compounds from environmental water samples. Detection of these contaminants was performed after pentafluorobenzylation at the low ng per liter level using gas chromatography/mass spectrometry. With multiple-component SIM programming simultaneous detection of all compounds in one single gas chromatographic run was possible. Increased reliability of acidic herbicide analysis from water samples with high matrix content was achieved by using a surrogate as well as an internal standard. 2-(4-chlorophenoxy) butyric acid, being a structural isomer of clofibric acid and mecoprop, was chosen as surrogate standard because cloflbric acid was found to be a widespread contaminant in environmental water samples from the Berlin area. Mecoprop, dichlorprop and 1-naphthylacetic acid were also found in field studies of some of these samples. A few examples of positive findings ...

Residue analysis of pesticides in food by two-dimensional gas chromatography with capillary columns and parallel detection with flame-photometric and electron-capture detection

Abstract Two-dimensional gas chromatography on two capillary columns is used for pesticide residue analysis in food samples. Both columns are connected by effluent splitting to the selective flame-photometric and electron-capture detectors, which are linked on-line to independent data processing channels. About 100 halogenated and organophosphorus pesticides, together with three internal standards, are screened on the first column with methylsilicone as the stationary phase. The compounds are recognized by their retention data and response to the two selective detectors. In a second analysis, peaks eluted from the first column are transferred by means of pneumatic switching to the second column with phenyl cyanopropyl methylsilicone as the stationary phase. This cutting of narrow fractions can be executed with high accuracy and reproducibility (“live chromatography”) by using time programming of the cutting valve. The final identification of all investigated pesticides is achieved by evaluating the set of linked retention data and, additionally, the response ratio of the two detectors characteristic for each compound. The application of the method to two real food samples, fortified with chlorinated and organophosphorus pesticides, is demonstrated.

Large-volume injection in residue analysis with capillary gas chromatography using a conventional autosampler and injection by programmed-temperature vaporization with solvent venting

Large-volume injection in capillary gas chromatography may be used to compensate for the limited detection sensitivity of selective detectors when further evaporation of sample extracts is not feasible owing to increasing losses of volatile solutes or because the analytical method can no longer be performed automatically. Large-volume injection using programmed-temperature vaporization (PTV) with solvent venting has proved its worth as an on-line pre-chromatographic sample concentration technique that permits the reproducible analysis of pesticide residues over a wide volatility range. Automated sampling and injection of a 12.5-μl volume of toluene extract using an HP 7673A autosampler with a 25-μl Hamilton syringe is described. The various parameters, including design of injector inlet, speed of injection, retention gap and initial column temperature, are discussed and the optimization procedure for split flow-rate, solvent evaporation temperature, solvent venting time and splitless or transfer time is reported. A test mixture containing C12, C14 and C16 hydrocarbons, 1,7-dibromoheptane, 3,4-dichloroaniline, pentachlorobenzene, hexachlorobenzene and the pesticides heptenophos, propachlor, naled, lindane, heptachlor, aldrin, tetrachlorvinphos, dieldrin, p,p′-DDE and endrin in toluene was used, representing moderately volatile to high-boiling solutes and thermolabile compounds. Complete recovery of all compounds in the test mixture was achieved with the method developed. No degradation of the thermolabile pesticides naled and endrin was observed. The precisions of quantitative determinations of 12.5-μl autosampler injections at different concentration levels were good to excellent down to concentration levels representing 1–2.5 ng per pesticide injected when applying atomic emission detection (AED). Data on standard deviations and the wide dynamic range of all test solutes are reported.

Determination of phenoxyalkanoic acids and other acidic herbicides at the low ppt level in water applying solid-phase extraction with RP-C18 materi

Abstract A method for the determination of 34 phenoxyalkanoic acids and other acidic compounds in water samples was developed. Recoveries were made from 11 of d

Determination of thermolabile urea pesticides after derivatization with HFBA using GC-ECD and confirmation by means of GC-MSD

SummaryThe determination of urea pesticides is difficult by means of gas chromatography because they undergo thermal decomposition when applying standardized chromatographic conditions as used in multiresidue analysis. A method is therefore described to make possible the detection of these compounds by gas chromatography after derivatization with HFBA using either electron capture and nitrogen-phosphorus detection or a mass spectrometer as detector.

Application of capillary gas chromatography with mass selective detection to pesticide residue analysis

Abstract A random sample of 76 pesticides with good gas chromatographic properties has been collected in order to test the applicability of the mass selective detector HP MSD for pesticide residue analysis. Using a capillary column, mass spectra of good quality were produced with 10 or 20 ng of each pesticide. Seventy two compounds were not only identified at this concentration with the PBM (probability based matching) search routine in the NBS library, but also remarkably with the best fit in the corresponding hit list. Lower concentrations can be detected only with selected ion monitoring (SIM). A mixture of 18 chlorinated pesticides was added to green pepper at the 10 ppb level. All compounds were detected with SIM using special time programming in one gas chromatogaphic analysis. The detection sensitivity of the mass selective detector in SIM mode approaches that of established selective detectors. The reliability of the results with respect to the identity of a pesticide residue, however, is orders of magnitude better. Therefore, this detector is a valuable tool for performing confirmatory analysis.