SAMPLE CLEANUP BY SOLID-PHASE EXTRACTION FOR THE ULTRATRACE DETERMINATION OF POLYCHLORINATED DIBENZO-P-DIOXINS AND DIBENZOFURANS IN BIOLOGICAL SAMPLES

A sample cleanup method for the isolation of polychlorinated dibenzo-p -dioxins (PCDDs) and dibenzofurans (PCDFs) by solid-phase extraction i s described. A C18 bonded silica cartridge is used for the initial ext raction and enrichment of the analytes. Subsequent cleanup is achieved with a dual-cartridge arrangement consisting of a bonded benzenesulfo nic acid cartridge in series with a silica cartridge. A Florisil cartr idge is employed for the final cleanup step. Sample preparation proced ures used for blood plasma and animal tissues are described. The preci sion and accuracy of the method is validated by determining recoveries of 2,3,7,8-substituted PCDD and PCDF congeners spiked at various leve ls in blood plasma and in animal tissues. The effectiveness of the cle anup method is shown by the analysis of wild bird eggs which are highl y contaminated with a variety of pesticides and polychlorinated biphen yls. The application of this cleanup method to human plasma containing PCDDs/PCDFs at parts-per-quadrillion levels and results of analyses b y high-resolution mass spectrometry and low-resolution mass spectromet ry are presented. The validity of this method is demonstrated by the c omparable results obtained from this method and from other established methods.