A method for the analysis of multiple novel halogenated flame retardants in cow’s milk

Abstract

ABSTRACTA method was developed for the extraction and analysis of cow’s milk to measure 21 halogenated flame retardants (FRs), including individual isomers plus eight methoxy-polybrominated diphenyl ethers (MeO-PBDEs). Extraction was performed using homogenisation with acetone:hexane with size exclusion chromatography followed by adsorption chromatography clean-up. Analysis was undertaken using gas chromatography high-resolution mass spectrometry. The method was validated in fortified cow’s milk with FRs and 2-methoxy-PBDE 68 at three levels (low [12.5–1250 pg g–1], mid [37.5–5000 pg g–1] and high [400–10 000 pg g–1]). Additional methoxy-PBDEs were tested at two fortification levels. Isotope dilution was used to correct for losses during sample preparation and average recoveries ranged from 58% (allyl 2,4,6-tribromophenyl ether [ATE]) to 121% (γ-tetrabromoethylcyclohexane (γ-TBECH)). Limits of detection ranged from 0.055 pg g–1 (6-methoxy-PBDE 47) to 38.9 pg g–1 (decabromodiphenylethane (DBDPE)). Matrix effects were overcome through the use of surrogate and performance standards. A single FR (1-bromomethyl-2,3,4,5,6-pentabromobenzene [PBBB]) and two methoxy-PBDEs were detected in commercially available cow’s milk collected from local supermarkets in Ottawa, ON, Canada. Detection frequency was < 25% for these compounds and, where present, concentrations were low.