DETECTION OF ALKYLATED POLYCHLORODIBENZOFURANS AND ALKYLATED POLYCHLORODIBENZO-P-DIOXINS BY TANDEM MASS-SPECTROMETRY FOR THE ANALYSIS OF CRUSTACEAN SAMPLES

In the present paper we report on a high resolution gas chromatography tandem mass spectrometer (HRGC/MS-MS) technique for the selective and sensitive detection of alkylated polychlorodibenzofurans (R-PCDFs) and alkylated polychlorodibenzo-p-dioxins (R-PCDDs). This method was compared to low resolution electron impact ionization, EI, while employing selected ion monitoring (SIM), as well as negative chemical ionization, NCI, with methane as reagent gas using available standards. It was found that the MS/MS technique was the most selective and sensitive method for analysis of these compounds. NCI showed low sensitivity and was therefore a poor alternative. EI (SIM) was the most sensitive method with high S/N ratios but did not provide the same selectivity as the new MS/MS method. HRGC retention indexes and relative retention times for R-PCDFs/R-PCDDs standards were calculated for positive identification purposes. Recoveries of R-PCDFs and R-PCDDs in different fractions using a clean up procedure for analyses of dioxins (PCDDs/PCDFs) in biological samples were acceptable for R-PCDFs and R-PCDDs. Analyses of crustacean samples confirmed these results. R-PCDFs were identified in crab samples from the Swedish west coast; we could not however identify R-PCDDs in the samples. Earlier research identified R-PCDFs in sludge and sediments and the bioaccumulation of these compounds is now suggested here. The R-PCDFs were present in these samples at concentration levels up to 10 times higher than those of the polychlorodibenzofurans (PCDFs). The congeners found in the samples had 1-4 chlorine atoms and 1-4 methyl groups.