Quadrupole ion storage tandem mass spectrometry and high-resolution mass spectrometry: complementary application in the measurement of 2,3,7,8-chlorine substituted dibenzo-p-dioxins and dibenzofurans in US foods

The US Food and Drug Administration has simultaneously utilized both high-resolution mass spectrometry (HRMS) and quadrupole ion storage tandem mass spectrometry (QISTMS) in the measurement of polychlorinated dibenzo-p-dioxins/dibenzofurans (PCDD/Fs) in 147 food samples collected in 1998 and 1999 in the US. In 1998, 20 egg samples, six scallop, 10 blue crab, eight American lobster, 10 pollack, 15 striped bass, five rockfish, 10 crawfish, seven aqua-cultured and 13 wild-caught salmon, along with 19 cream and 18 mozzarella cheese samples were measured for PCDD/Fs. QISTMS provided limits of detection (LODs) close to those produced using HRMS for many congeners in 56 samples analyzed by both techniques in 1998 and three salmon and three striped bass collected in 1999. The I-TEQs of the mean levels for measured congeners in 40 samples of fish and shellfish and 16 cheese and eggs from 1998 analyzed by HRMS and QISTMS were 0.99 and 1.1 ng/kg wet weight, respectively. The I-TEQ for mean congener levels in the 40 fish and shellfish measured by HRMS was 1.4 ng/kg wet weight. A higher sample throughput with greater data quality at a lower cost is achievable by using both QISTMS and HRMS.