Mass-Profile Monitoring in Trace Analysis: Identification of Polychlorodibenzothiophenes in Crab Tissues Collected from the Newark/Raritan Bay System

Tetra- and pentachlorodibenzothiophenes (TCDT and P₅CDT) and the sulfur analogues of tetra- and pentachlorodibenzofurans (TCDF and P₅CDF) were identified along with polychlorodibenzo-p-dioxins and dibenzofurans (PCDD/Fs) in tissues of crabs collected from the Newark/Raritan Bay system. The use of mass-profile monitoring of selected ions in capillary gas chromatography/highresolution mass spectrometry (GC/HRMS) resulted in a preliminary identification of an isomer of TCDT and of P₅CDT. Confirmation for this identification was accomplished by high-resolution peak matching and by acquiring a full spectrum by GC/MS. The accurate masses of three molecular ions, the full electron ionization (El) mass spectrum, and the chromatographic retention time are all consistent with those of a 2,4,6,8-TCDT standard. Levels of 2,4,6,8-TCDT in the crab tissues are more than 5–10 times those of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD); the highest level (12 ppb) occurring in the hepatopancreas tissue of crabs taken from Newark Bay. A good correlation was found between the levels of 2,3,7,8- TCDD and 2,4,6,8-TCDT (r² = 0.98) in the samples collected from four stations in the area, suggesting common sources of 2,4,6,8-TCDT and 2,3,7,8-TCDD.