부산대학교 도서관

Mass spectrometry using 10 eV electron impact was employed in the analysis of Mirex residues in the presence of PCB's. Low voltage MS is a useful complementary tool for positive identification of both Mirex and PCB residues in organic extracts.The MS patterns of pure 2, 4, 5, 2′, 5′-pentachloro and 2, 5, 2′, 5′-tetrachlorobiphenyl and of mixtures of PCB isomers in Aroclor 1254- and 1260 are simple and distinguishable from the MS spectrum of Mirex. There is no overlapping of ions (molecular or fragment) of PCB's with those of Mirex. Each pure chlorobiphenyl has its base peak at the molecular ion (M) in contrast to Mirex which exhibits the intense M/2 ion (m/e 270) as base peak. In mixtures of PCB's, peak clusters, 34 mass units apart, correspond toC12H10-xClx where x = 4 to 9.A mixture of 500 μg of Mirex and 500 μg of Aroclor 1254 added to 5 g of pork fat was detected by low voltage MS in the crude recovery extract. A probe temperature of 90 or 100°C was satisfactory for identification of each component in the mixture. However, when the probe temperatures reached 140°C or above, interference by extraneous peaks became more serious and most of Mirex and PCB's were depleted. The presence of these extraneous peaks indicated that the treatment of fat extracts by either 24-hr stirring in concentrated H2SO4 or by a single florisil column chromatography did not remove fatty residues satisfactorily. Thus, “standard” techniques of Mirex residue cleanup may be inadequate.