Determination of Polybromo Diphenyl Ethers and Hexabromobiphenyl in Soil by Gas Chromatography-Mass Spectrometry with Separation by Accelerated Solvent Extraction

After air-drying and rejecting mixed sand and stone, the soil was gound to pass the sieve with mesh-diameter of 0.18 mm. A portion (2.000 g) of the soil sample was mixed homogeneously with 2.0 g of diatomite, and to this sample mixture, 50 μL of the isotopic internal standard solution (2 000 μg·L^-1 MBDE-MXFS) and 40 μL of 5 000 μg·L^{-1 13}C₁₂-BDE-209 standard solution were added and this mixture was extracted by accelerated solvent extraction (ASE) with mixed solvent of n-hexane and dichloromethane (1+1). The extract obtained was evaporated to 1-2 mL, and purified by passing through multilayer silica gel column. Analytes on the column were then eluted with 100 mL of n-hexane, and the eluate was collected and evaporated to 1-2 mL and further concentrated to 0.1 mL by N₂-blowing. Then 50 μL of sample introducing internal standard solution of 2 000 μg·L^{-1 13}C₁₂-BDE-138 were added and its total volume was made up to 1.0 mL, which was used for GC-MS analysis. For determination of trilbrono- to hepta-bromo diphenyl ethers (PBDEs) and hexabromobiphenyl (BB-153), instrumental conditions of GC-EI/LRMS and chromatographic column of Rtx-1614 (30 m×250 μm, 0.10 μm) were used, while for determination of BDE-209, the instrumental conditions of GC-NCI/LRMS and the column of Rtx-1614 (15 m×250 μm, 0.10 μm) were used. Linearity range found for BDE-209 was 50.0-1 000 μg·L^-1, and those for the remainder 7 PBDEs and BB-153 were found same 5.00-500 μg·L^-1. Values of detection limits (3s) found ranged from 0.04 to 0.51 μg·L^-1. Recovery was tested by standard addition method, and values of recovery found were in the range of 82.6%-112%. RSDs (n=5) found ranged from 1.8% to 8.6%.