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Over thirty years experience of laboratory intercalibration for the analysis of chlorinated hydrocarbons in the various environmental samples

Analytical methods commonly used in analysis of chlorinated hydrocarbons in environment are time consuming, labour-intensive, costly and often very dubious. This is because the investigated pollutants, which are present mostly at parts per billion (PPB) levels in soil, sediments and biota, and parts per trillion (PPT) in water, have to be concentrated and separated from the matrix (sample clean-up) so that they can be identified and measured – mainly by ECD gas chromatography applied in monitoring programmes. Applicability of monitoring data depends on their quality measured in terms of reliability, which depends on precision (reproducibility) and accuracy (true values). The accuracy of the results is evaluated applying participation in inter-comparison runs with the samples of composition similar to the environmental samples. To improve the reliability and accuracy of the obtained monitoring data, participating institutions have taken part in standardisation and inter-calibration exercises organized on national or international levels. Since 1973, the Monaco Laboratory of IAEA has organized regular inter-comparison exercises on a worldwide and regional scale. Rudjer Boskovic Institute (RBI) from 1974 took part in inter- calibration exercises organized by IAEA. Based on the frequency of participation and the quality of the data reported, the IAEA has issued a list of selected laboratories around the Mediterranean for trace organochlorine compound analysis. Of the 56 laboratories from 14 Mediterranean countries that participated in the inter-calibration runs to determine chlorinated hydrocarbons in marine samples, six were selected for excellent analytical performance. Among them was only RBI from former Yugoslavia. Even after these excellent results RBI laboratory continue to take part in inter-calibration exercises organized by IAEA for determination CHCl compounds in seven various samples (sediment – 2 samples, mussel – 3 samples, seaweed-fucus, and tuna fish in period from 1995 to 2005). In total, 14 to 87 laboratories, from 8 to 43 countries, took part in these exercises. In addition to IAEA inter-comparison runs, RBI took part in further inter-calibration exercises: 1) QUASIMEME Laboratory Performance Studies (Round 26 and Round 28 – altogether 3 sediment and 3 biota samples) 2) QualcoDanube inter-comparison study (waste water extracts and sediment samples – altogether 7 samples) 3) European Commission – The Fifth Framework Programme (Call Identifier INCO- COPERNICUS-ICFP501A2PR02) APOPSBAL Project. Exercises were done on two references samples (standards and soil) and “ home made” homogenous very polluted soil samples with PCBs. These exercises were international, with participation from many laboratories from Danube region countries for Danube exercises, and five laboratories from partners of APOPSBAL Project. The paper will present and discuss all results of RBI laboratory in before mentioned inter- calibration exercises.

PCB; DDT; intercalibration; chlorinated hydrocarbons; reference materials

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