Biomonitoring: Polybrominated Diphenyl Ethers and Polybrominated Biphenyls Using Capillary GC with Electron-Capture Negative Ion Mass Selective

Polybrominated diphenyl ethers (PBDEs) have emerged as a significant class of persistent organic pollutants (POPs). These POPs join the organochlorine pesticides (OCs) and polychlorinated biphenyl (PCB) and polybrominated (PBB) biphenyl congeners as environmentally significant POPs that must be biomonitored continuously. Potential threats to human and animal health include developmental neurotoxicity, endocrine disruption, peripheral nervous system damage and cancer (1,2). Morland and colleagues (3) cite two reported adverse health outcomes in laboratory animals dosed with high levels of PBDEs to include neurologic deficiencies and endocrine disruption . Sjödin and colleagues (4) at the Centers for Disease Control and Prevention (CDC) report an increase in the concentration of PBDEs measured in 40 human serum pools collected in the southeastern United States from 1985 through 2002 and in Seattle, Washington, from 1999 through 2002. In contrast, 2,2',4,4',5,5'-hexabromobiphenyl (BB-153), the principal PBB congener from the original Firemaster (Formerly the Michigan Chemical Corporation, St. Louis, Missouri) fire retardant product that inadvertently contaminated livestock and entered the human food chain in Michigan in 1973 (5,6) as well as 2,2',4,4',5,5'-hexachlorobiphenyl (CB-153) also were measured and found to be decreasing over this time period. Sjödin and colleagues (7) at the CDC recently reported serum concentration levels of 10 BDE congeners and BB-153 in representative sampling of U.S. residents in 2003 and 2004. Out of 2062 serum samples, almost all serum samples contained detectable levels of BDE-47.

Covaci and colleagues (8) recently reviewed the literature on the isolation and recovery of PBDEs from both environmental and human samples. They stated that when it is impossible to use ¹³C-labeled PBDEs as internal standards, PBDE congeners that are not present in technical mixtures or environmental samples are suitable as internal standards. Fluorinated derivatives (F-PBDEs) also make suitable internal standards. Many laboratories cannot afford high resolution mass spectrometers that would allow use of ¹³C-labeled PBDEs to be able to quantitate PBDEs by isotope dilution. Korytár and colleagues (9) established elution orders for seven different GC stationary phases and concluded that one of the columns resulted in the least number of coelutions.

In this article, we demonstrate how a PTV injector was incorporated along with a 30-m WCOT column in a capillary GC–MS system utilizing electron capture negative ion with selected ion monitoring (ECNI-MSD) detection using methane as buffer or reagent gas to achieve sufficient chromatographic resolution of the most commonly detected PBDE congeners. Baseline chromatographic resolution of BB-153 from BDE-154 without resorting to a longer WCOT column was demonstrated. We show that the incorporation of an internal standard mode of instrument calibration led to a significant cost reduction to quantitate PBDEs and PBBs in sample extracts from biological matrices. To assess instrument sensitivity, we then studied the calibration data generated over a six-month period. Using an ordinary (nonweighted) least squares regression approach, the author established decision levels, decision limits, and instrument detection limits (IDLs) for each congener based upon calibration statistics using computer programs published elsewhere (11). Our objective was to achieve the lowest IDLs for nine BDE congeners and two BB congeners and, thus, to add value to an existing biomonitoring program in public health for the state of Michigan.