Polychloro-n-alkanes (PCAs), also known as chlorinated paraffins (CPs), are chlorinated organic compounds, that are produced since the beginning of 1930´s for industrial application. Today, this class of compounds represents the largest group among the chlorinated hydrocarbons, that are produced and find application. The PCA formulations consist of a mixture of thousands of PCA components, which can be categorised into short chain (C10-C13), medium chain (C14-C17) and long chain (C>17) compounds. Because of the complex composition of the PCA mixtures and the difficulties involved in the work-up, identification and quantification of their components, compared to the other anthropogenic compounds, world wide relatively little useful data are available on PCA concentrations in the ecosphere. In the frame of this work, primarily, a selective clean-up technique is developed for separation of the short and medium chain PCAs from lipid impurities and interfering organochlorine compounds (OCs), especially from toxaphene, in selected fatty foods. Furthermore, for determination of the PCA residues different independent detection methods and several external standards are applied. The results thus obtained with the different methods are compared with each other and their environmental relevance assessed. The clean-up technique developed here consists of three (work-up) steps. The first one includes the simultaneous column extraction of the fatty material, the PCAs and other interfering OCs accumulated into the fat, as well as the decomposition of the fat and other H2SO4-labile compounds. The second step involves the decomposition of the remaining lipids (0.01%), as well as the separation of the PCAs from the most part of the interfering compounds. In the concluding third step the quantitative PCAs separation from the rest of the interfering substances is carried out by a final Gel Permeation Chromatography step. The recoveries of C10-C13 PCAs with 45%, 56% and 63% chlorine content (w/w) amounted about 90%, 92% and 94%, respectively. By C14-C17 with 52% chlorine content (w/w) the recovery averaged to 93%. The quantification of PCA residues in the selected fatty samples (the fish, mussel, fish oil and cod liver oil samples as well as deep sea shrimps and fish feed) is carried out by three independent detection methods (HRGC/ECD, HRGC/LRMS-ECNI in SIM mode with time windows and SCGC/LRMS-ECNI in full scan mode). By using the ECD technique PCA residues (C10-C13, C14-C17 und C>17 PCAs) are detected in about 67% of the selected samples. For a selective determination of the individual C10 to C17 PCAs, as well as C10-C13 and C14-C17 PCA mixtures in the environmental samples, SCGC/LRMS-ECNI in full scan mode and HRGC/LRMS-ECNI in SIM mode with time windows are utilised. As external standards, pure laboratory synthesised C10, C11, C12, C13 PCAs with 45 to 70% chlorine content (w/w) and C14-C17 with 52% chlorine content (w/w) are used. The results show that the quantification using pure synthesised components mixtures gives more accurate residue values. Owing to these facts, for the assessment of PCAs contamination in the food samples examined only those ascertained values are considered, that have been obtained by SCGC/LRMS-ECNI in full scan mode with pure synthesised C10 to C13 PCAs with 45 to 70% chlorine content (w/w). In most of the samples the part of the C10-C13 PCAs, compared to the total quantified PCAs (116.0-1719.3 µg/kg fat), lies between 60 and 80%. The ratio of short chain to medium chain PCAs depends, in general, on the nature of the sample investigated. In the fish feed samples from Germany, as well as in the cod liver oils from France and the U.S.A., however, the medium chain PCAs are the most predominant. Remarkable are the C14-C17 PCA residues in the fish feed (1550.2 µg/kg fat), for which occurrence no satisfactory explanation could be given.     «

Polychloro-n-alkanes (PCAs), also known as chlorinated paraffins (CPs), are chlorinated organic compounds, that are produced since the beginning of 1930´s for industrial application. Today, this class of compounds represents the largest group among the chlorinated hydrocarbons, that are produced and find application. The PCA formulations consist of a mixture of thousands of PCA components, which can be categorised into short chain (C10-C13), medium chain (C14-C17) and long chain (C>17) compounds...     »