Determination of eight polybrominated diphenyl ethers in marine sediments by ultrasonically assisted alkaline degradation extraction and gas chromatography-electron capture detection

Abstract

For determination of the eight polybrominated diphenyl ethers (PBDEs) in marine sediments based on gas chromatography-electron capture detection (GC-ECD), a rapid and effective method for simultaneous sample extraction and purification was developed, in which ultrasonically assisted alkaline hydrolysis was combined with solvent extraction. The sediment sample was processed in an ultrasonic bath in 2. 00 mol/L NaOH-methanol solution for 30 min, and subsequently extracted by n-hexane. The organic phase was then separated and purified by silica column and concentrated to 100 µL for GC-ECD analysis. Under the optimized conditions, the recoveries and relative standard deviations (RSDs) for eight PBDE congeners ranged from 63.6% to 110.3% and from 1.7% to 10.5% (n = 5), respectively. The limits of detection (LODs, S/N = 3) ranged from 0.002 to 0.011 ng/g except for deca-brominated diphenyl ether (BDE-209), which was 0.097 ng/g. With high accuracy, good stability and adequate recovery, the established method was successfully applied to the analysis of PBDEs in the surface sediments from Bohai Sea. The concentrations of ∑8PBDEs (sum of 2,4,4'-tribromodiphenyl ether (BDE-28), 2,2',4,4'-tetrabromodiphenyl ether (BDE-47), 2, 2', 4, 4', 5-pentabromodiphenyl ether (BDE-99), 2, 2', 4, 4', 6-pentabromodiphenyl ether (BDE100), 2, 2', 4, 4', 5, 5'- 1.566 to 6.760 ng/g and from 1.461 to 6.438 ng/g, respectively. A decreasing gradient of concentration was basically observed with increasing distance off the shore, indicating that anthropogenic activities, surface runoff and river inputs may be the sources of PBDEs in the sediments from Bohai Sea.