Jürgen Burhenne

Primary photoproducts and half-lives

The photolytically induced decomposition of fluoroquinolone carboxylic acids (enrofloxacin, danofloxacin, ciprofloxacin and norfloxacin) at concentrations of 10 mg/l in pure water and an irradiation intensity of 200 W/m2 (xenon lamp) led to half-lives from 20.6 min (danofloxacin) to 105.9 min (norfloxacin). The environmental half-life of enrofloxacin was calculated by the GCSOLAR program and resulted in 1.8 to 55.4 hours, depending on the season and degree of latitude. During the irradiation procedure, products were built up which primarily demonstrated alterations involving the piperazine ring as compared with the parent compounds. The amount of14CO2 evolved by the photomineralization of14C-labeled enrofloxacin reached 26.4 % of the applied radioactivity. The main photoproducts were isolated by HPLC and their structural elucidation was carried out by different spectroscopic methods (MS, GC/MS and1H-NMR).

Preparation and structure of high-chlorinated bornane derivatives for the quantification of toxaphene residues in environmental samples

SummaryThe HRGC-determination of Taxophene® residues in the presence of other chlorinated hydrocarbons with similar retention times is often difficult. This problem can satisfactorily be overcome by using purely isolated high-chlorinated bornane derivatives (7–17) as standard. The method is highly selective for measuring toxaphene in complex environmental matrices, such as fish, and can also be used for evaluating the changes in the relative distribution that may have resulted from bioaccumulation and environmental transformation.

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.

Photolytic degradation of fluoroquinolone carboxylic acids in aqueous solution

Subsequent to irradiation with a xenon lamp simulating sunlight, fluoroquinolone carboxylic acids in aqueous solution form polar pyridone dicarboxylic and tricarboxylic acids. After liquid/liquid partition with chloroform/water these substances can be isolated by ion exchange chromatography of the aqueous phase. They can be regarded as intermediate compounds on the route to a complete photomineralization. The structural elucidation is performed by such mass spectroscopic methods as MS, GC/MS and HPLC/MS, whereby HPLC/MS shows the highest reliability. Additionally1H- and13C-NMR measurements confirm the structure of the main polar degradation product.Subsequent to irradiation with a xenon lamp simulating sunlight, fluoroquinolone carboxylic acids in aqueous solution form polar pyridone dicarboxylic and tricarboxylic acids. After liquid/liquid partition with chloroform/water these substances can be isolated by ion exchange chromatography of the aqueous phase. They can be regarded as intermediate compounds on the route to a complete photomineralization. The structural elucidation is performed by such mass spectroscopic methods as MS, GC/MS and HPLC/MS, whereby HPLC/MS shows the highest reliability. Additionally(1)H- and(13)C-NMR measurements confirm the structure of the main polar degradation product.

Polar photodegradation products of quinolones determined by HPLC/MS/MS

The photochemical degradation of quinolones in aqueous solution proceeds in two main steps. The first step is the degradation of the piperazine substitution forming 7-amino compounds which are more stable against photolysis than the corresponding parent compound. Further photochemical degradation down to CO2 formed intermediate polar substances. By liquid/liquid partition with chloroform/water, ion exchange chromatography and semipreparative HPLC the polar compounds could be isolated. The structures of the photolytically formed pyridone tri- and dicarboxylic acids were elucidated on the basis of HPLC/MS/MS measurement. Additionally the half-life of the main polar compound, 1-cyclopropyl-pyridone-2,3,5-tricarboxylic acid was analysed by HPLC.

Isolation and structural elucidation of polar photometabolites.

Subsequent to irradiation with a xenon lamp simulating sunlight, fluoroquinolone carboxylic acids in aqueous solution form polar pyridone dicarboxylic and tricarboxylic acids. After liquid/liquid partition with chloroform/water these substances can be isolated by ion exchange chromatography of the aqueous phase. They can be regarded as intermediate compounds on the route to a complete photomineralization. The structural elucidation is performed by such mass spectroscopic methods as MS, GC/MS and HPLC/MS, whereby HPLC/MS shows the highest reliability. Additionally1H- and13C-NMR measurements confirm the structure of the main polar degradation product.Subsequent to irradiation with a xenon lamp simulating sunlight, fluoroquinolone carboxylic acids in aqueous solution form polar pyridone dicarboxylic and tricarboxylic acids. After liquid/liquid partition with chloroform/water these substances can be isolated by ion exchange chromatography of the aqueous phase. They can be regarded as intermediate compounds on the route to a complete photomineralization. The structural elucidation is performed by such mass spectroscopic methods as MS, GC/MS and HPLC/MS, whereby HPLC/MS shows the highest reliability. Additionally(1)H- and(13)C-NMR measurements confirm the structure of the main polar degradation product.

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.