Harun Parlar

Spectroscopic characterization of environmentally relevant C10-chloroterpenes from a photochemically modified toxaphene standard

Twenty-five pure environmentally relevant toxaphene components have been isolated from photochemically modified technical toxaphene by means of a combination of column chromatography on silica gel and preparative high resolution liquid chromatography. These compounds are 6 chlorinated camphenes (1–3, 5, 7, and 11) and 19 chlorinated bornanes (4, 6, 8–10, 12–16, 18–24, 26, and 27 according to Table 1). Two further chlorobornanes (17 and 25) have been isolated from a highly chlorinated mixture obtained by the excess chlorination of 2-exo,10-dichlorobornane. The structural elucidation of the isolated compounds has been carried out with spectroscopical methods.

Enantiomer selective separation of toxaphene congeners isolated from seal blubber and obtained by synthesis

Abstract Stationary phases based on dimethyl-t-butylsilylated heptakis(2,3,6-tri-O-methyl)-β-cyclodextrin diluted with different polysiloxanes were developed for the enantiomer separation of chiral toxaphene congeners by high resolution gas chromatography (HRGC). They allowed to determine the enantiomer ratio of an octa- and nonachloro congener isolated from seal blubber. The found ratios of 1,024 and 1,059 were very close to those of the racemates and indicate that enantiomer selective metabolisation is not significant in seals. Furthermore, the enantiomer separation of 11 racemic toxaphene congeners obtained by synthesis was also performed. Two of them had the same retention times as the isolated congeners on 3 or 5 stationary phases, respectively, and similar negative ion chemical ionisation mass spectra. First attempts are made to explain differences in the observed enantiomer separations by the steric structure of the congeners. In addition, general aspects and difficulties of enantiomer selective separations by HRGC are discussed.

Theoretical consideration of the structural variety in the toxaphene mixture taking into account recent experimental results

Abstract There are still wide differences in the number of congeners estimated and measured for the insecticidal toxaphene mixture. Purely theoretical considerations are not very helpful, since compounds with the most unlikely Cl substitution are counted and included just like those that are known and already isolated. Counting the substances with the aid of a high resolution GC-MS system can, aside from the errors that are involved, not provide any structural information except whether the compounds are saturated or unsaturated. For this reason it is not known what chlorine substitutions are possible for the bornanes and accordingly which are present in the mixture. Recent results on the isolation and structural elucidation of 27 congeners form the basis for postulates made in this contribution concerning the structure of chlorinated bornanes and a calculation of the number of significant toxaphene components. This allows a concrete picture to be formed of this class of substance.

HRGC-ECD and HRGC-NICI SIM quantification of toxaphene residues in selected marine organism by environmentally relevant chlorobornanes as standard

Abstract The HRGC determination of Toxaphene R residues in fish tissues is often difficult because of the differing accumulation behaviour and decomposition rates of the individual Toxaphene compounds. This problem can satisfactorily be overcome by using purely isolated environmentally relevant chlorinated bornane derivatives (Parlar Nr. 26, 32, 50, 42, 69). The method is highly selective for measuring Toxaphene residues in complex marine organism matrices.

Structure elucidation of the three most important toxaphene congeners by X-ray analysis

Abstract Three of the most frequently detected toxaphene components in environmental samples are the chlorobornanes 2-exo,3-endo,5-exo,6-endo,8b,8c,10a,10b-octachlorobornane (Parlar No. 26 ); 2-exo,3-endo,5-exo,6-endo,8b,8c,9c,10a,10b-nonachlorobornane (Parlar No. 50 ), and 2,2,5,5,8b,8c,9c,10a,10b-nonachlorobornane (Parlar No. 62 ), whose structures could not be completely elucidated by spectroscopical methods. This paper now describes the X-ray structure analysis of the three compounds and presents their exact crystal structure.

Isolation and characterization of environmental relevant single toxaphene components

Abstract The gaschromatographic determination of Toxaphene and its residues in different environmental compartments is often difficult. This problem can satisfactorily be overcome if purely high chlorinated bornane derivatives are available. In the present work it was able to isolate large quantities of eleven of these highly chlorinated Toxaphene components (7–17) and to elucidate their structures with the help of spectroscopical methods.

Quantification of toxaphene residues in fish and fish products using a new analytical standard

Toxaphene, the most heavily used chlorinated hydrocarbon insecticide, is difficult to quantify, because it is a mixture of more than 200 compounds, primarily polychlorinated bornanes1–5). These components elute over a wide range of GC retention times and are not completely resolvable even by capillary columns. Interferences with other organochlorine contaminants cannot be excluded6–8). Some of the interfering compounds can be eliminated by adsorption column chromatography9,10). Unfortunately, any additional clean-up procedure reduces recoveries, causes poor reproducibility and thus, compromises accuracy and sensitivity. Selectivity can be achieved by use of negative ion mass spectrometry - selected ion monitoring (NICI-SIM)11–14). The GC analyses of environmental samples are furthermore complicated by changes in the original composition of the chlorobornanes due to chemical and metabolic conversions9). Differences in the degree of chlorination or in positional isomerization influence NICI-SIM response significantly8). Quantification using a technical standard can therefore lead to erroneous results. Considering conversion and accumulation processes of toxaphene components in the environment, we have prepared a chlorobornane mixture, yielding a GC-NICI-SIM chromatogram, which resembles very much that of the residues obtained from different fish tissues. It was demonstrated, that this mixture can be used as representative standard for the exact quantification of toxaphene residues in fish and fish products.

Elimination of interfering compounds during GC determination of toxaphene residues by photodechlorination reactions

SummaryThe HPGC determination of Toxaphene in the presence of other chlorinated hydrocarbons with similar retention times is often difficult. This problem can be satisfactorily overcome by including photodehalogenation reactions of interfering substances. Irradiation of the extracts after clean-up procedures in protonated solvents with wavelengths at 254 nm lead to photodechlorinated products of these compounds with shorter retention times, while Toxaphene is mostly stable and can therefore be quantitatively determined by gas-chromatography.

Vergleichende Untersuchungen über das Vorkommen von Toxaphenrückständen

Zusammenfassung The concentration levels of polychlorinated bornanes (Toxaphene R ) were determined in different kinds of samples from Europe and Nicaragua using a new GC/EC method, basing on photodegradation of the interfering substances (e. g. PCBs) with wavelengths at 254 nm. Other polychlorinated compounds (PCBs and DDE) were also detected. Surprisingly high amounts of chlorinated bornanes were found in Europe in fish and fish products. The data confirm the general assumption, that chlorinated bornanes are present in environmental samples in high quantities.

The detection of aluminium complexes in forest soil solutions and beech xylem saps

SummaryAn ion-pair chromatographic method in which aluminium is quantitatively determined via derivatization with 8-hydroxyquinoline-5-sulphonic acid was evaluated for its utility as a method for speciating Al in soil solutions and xylem saps. The results show that aluminium fluoride and several five- or six-membered chelate complexes are stable enough to be analyzed chromatographically.