[Chemical and effect-related analysis of dioxins and dioxinlike PCB's]. / Chemische und wirkungsbezogene Analytik der Dioxine und dioxinähnlichen PCB.

Dioxins and dioxinlike PCBs are high toxic and persistent compounds. They accumulate in the feed and food chain. Because of their occurrence in a very low concentration range, the established requirements for analytical methods are restrictive. Commission Directive 2002/69/EC of 26 July 2002 lays down sampling methods and methods of analysis for the official control of dioxins and dioxinlike PCBs in foodstuff. Confirmatory methods are high resolution gas chromatography/high resolution mass spectrometry (HRGC/HRMS). Screening methods could be used to select samples with significant levels of dioxins. Bioassay--for example the EROD-Bioassay--can be used as a screening method.

Results of an "emergency quality control study" as confirmation of a PCDD/PCDF-contamination of milk and butter samples.

Elevated PCDD/F levels in four butter samples and one milk sample had to be confirmed under considerable time pressure. These samples should demonstrate a raising dioxin contamination in different regions of Germany caused by the use of Brazilian citrus pulp as feedstuff. Above all, the increase of 2,3,7,8-TCDD and 1,2,3,7,8-PeCDD had to be confirmed. Thus, an "emergency quality control study" was performed including five laboratories from the official food control in Germany. The results had to be reported about two to three weeks after the first announcement of the samples (including time for shipment). The five laboratories applied different extraction and clean-up methods, used different GC-columns and GC/MS-equipment and different standard solutions. The results are in a good agreement. Slightly different results for most individual congeners were of minor importance. A difference was observed only in the 2,3,7,8-TCDF content of one laboratory which was not relevant for the evaluation of the increase of the dioxin contamination in milk and dairy products. The laboratory's individual methods proved to give correct results even under a very tight schedule.

Direct chemical ionization mass spectrometry of short-chain polysaccharides.

Underivatized short-chain polysaccharides such as two inulins from different plants containing up to 35-40 monosaccharide units with molecular weights of up to 6500 Da and dextran T 1.5 containing up to 16-20 monosaccharide units with molecular weights of up to 3200 Da have been investigated by direct chemical ionization. Under soft ionization conditions such as ammonia chemical ionization and reduced ion-source temperature, it was possible to obtain spectra of the native polysaccharides showing dominant ion series corresponding to ammonia adduct ions of oligosaccharides, and also ion series corresponding to ammonia adduct ions of anhydro-oligosaccharides.