DEVELOPMENT OF A MICROCOLUMN RADIOIMMUNOASSAY FOR SCREENING OF POLYCHLORINATED-BIPHENYLS IN MILK AND IN ANIMAL FATS

6-[I-125]Iodo-3,3',4,4'-tetrachlorobiphenyl and anti-3,3',4,4'-tetrachlorobiphenyl-6-azo-serum were used for the development of a Spheron microcolumn radioimmunoassay (RIA) which permits a screening detection of PCBs in cleaned up extracts from fat materials. The assay was negligibly sensitive to chlorinated pesticides and further aromatic and cyclic hydrocarbons. The developed method detected in the test tube 0. 1 ng of Delor 104, 105, or 106 (the corresponding formulations are Aroclor 1248, 1254, or 1260) and exhibited considerably lower sensitivity to Delor 103 (Aroclor 1242). The values obtained by means of RIA were comparable with those determined by GC in the detection range 0.088-5.58 mg of Delor 106 kg-1 of fat. Intra-assay variation coefficients in samples containing 0.5, 1.25, and 2.8 mg of Delor 106 kg-1 of fat were 21.2 (n = 40), 9.0 (n = 17), and 11.9% (n = 23), respectively; interassay coefficients for samples with concentrations of 0.5 and 2.8 mg of Delor 106 kg-1 of fat were 23.9 (n = 37) and 24.6% (n = 30), respectively. A specific application of the method for monitoring a contaminated cow herd is presented.