Determination of 36 Kinds of Halogenated Flame Retardants in Soils by GC/MS with an Accelerated Solvent Extraction-Online Purification Method

Halogenated flame retardants (HFRs) are persistent organic pollutants and have attracted much attention due to their bioaccumulation, long-range migration, and potential health risks. HFRs usually exist in trace levels in soil. Due to the complex soil matrix, severe interference, and significant differences in polarity, thermal stability, etc. among different types of HFRs, it brings challenges to the synchronous and accurate analysis of multiple types of HFRs. In the actual environment, HFRs often exist in the form of combined pollution. Therefore, it is necessary to establish an analytical method for the simultaneous extraction and detection of multiple HFRs to effectively monitor their residual levels in the soil environment. A method for the simultaneous analysis of 36 kinds of HFRs including polybrominated diphenyl ethers (PBDEs), polybrominated biphenyls (PBBs), dechlorane plus (DPs), polychlorinated biphenyls (PCBs) in soil has been established. By adding ethylenediamine-N-propyl (PSA) and Florisil to the sample through matrix solid-phase dispersion extraction (MSPDE), organic acids, pigments, lipids and polar interfering substances can be effectively removed, reducing matrix interference. After the samples were thoroughly ground for 5min, accelerated solvent extraction (ASE) was conducted at 80℃ and 1500psi using n-hexane-dichloromethane (1∶1, V/V) as the extraction solvent, static extraction for 10min, and two extraction cycles. After extraction and purification of the samples, the matrix interference was significantly reduced, and the recovery of each compound was higher than 60%. Using diatomite instead of the sample and undergoing the same pretreatment process to prepare the matrix-matching solution for the calibration curve effectively reduced the interference introduced in the experimental process. After correction by this curve, the recoveries of Syn-DP, Anti-DP, PBDE 206, and PBDE209 reached 72.8% to 123.5%. This method had a good linear relationship among PBBs, DPs and PCBs within the concentration range of 10–500μg/L (PBDEs: 50–500μg/L), with a coefficient of determination (R²) of no less than 0.998 and a detection limit of 0.15–4.5μg/kg. The method was applied to spiked actual samples, with recoveries ranging from 65.9% to 132.1%, and relative standard deviations (RSD) ranging from 2.1% to 24.3%, meeting the requirements of relevant standards and being suitable for the analysis of large quantities of complex samples.