Problems Encountered in the Determination of 2,3,4-2′4′5′ Hexachlorobiphenyl (CB 138) in Environmental Samples

Abstract
Selected individual chlorobiphenyls (CB) used for monitoring and tolerance purposes are checked on interferences using negative chemical ionization (NCI) mass spectrometry. An interference at the retention time of CB 138 (2,3,4-2′4′5′ hexachlorobiphenyl) was found. Quantitative results reported up till now and maximum residue limits (MRL) set for this compound are at least questionable.