# Chemicals from Brominated Flame Retardants: Analytical Methods, Occurrence, Transport and Risks
## 2 Analytical Methods for the Detection of BFRs in Environmental and Biological Samples
### Sample Collection and Extraction Methods
#### 2.1.2 Abiotics Samples
Further pretreatment may involve sieving the samples through a stainless-steel wire mesh of different sizes. Pretreatment methods for sewage sludge and biosolids may include centrifugation to separate solids, filtration to remove particulate matter, and the addition of chemicals such as acids or bases for pH adjustment. Additionally, the samples may undergo freeze drying or lyophilization to remove excess water content before further processing. Extraction and clean-up techniques take into account the matrix effects which can arise from the presence of organic matter, mineral content, and soil particles that may co-extract with BFRs and interfere with their detection during analysis. Similarly, in sewage samples, matrix effects can stem from the complex mixture of organic and inorganic compounds, suspended solids, and microbial content, which can impact the efficiency of extraction and the accuracy of BFR quantification. SE [44; 45] and PLE [46] were the major techniques reported for extraction of BFRs from sediment, sewage sludge, and biosolids. Both methods achieved high extraction efficiency and good recoveries of different BFRs. ASE has also been widely employed for the extraction of these samples. SE is a dependable, long-established technique known for its high recovery rates of non-polar compounds, though it requires a substantial amount of time and solvent. PLE enhances efficiency and recovery rates compared to SE, with lower solvent consumption and shorter extraction durations, making it effective for a wider variety of compounds. ASE delivers the highest efficiency and recovery rates, using minimal solvent and achieving the fastest extraction times, making it ideal for contemporary, high-throughput laboratories. Ultimately, the choice of extraction method should be guided by the specific requirements of the analysis, including the type of target compounds, the matrix involved, and the available resources and equipment. [PERSON] et al. [42] developed a simultaneous determination of ultra-trace TBBPA, tribromobiphenyl A (tri-BBPA), dibromobiphenyl A (di-BBPA), monobromobisphenol A (mono-BBPA), and bisphenol A (BPA) in soil and sediment samples found in Shuxi River by ASE and HPLC-MS/MS. The results showed recovery rates of over 79.40% and 75.65% in soil and sediment, the minimum detection limit was 0.0225\(\sim\)0.0525 ng g\({}^{-1}\), and RSD was less than 7.19%. Employing selective pressurized liquid extraction (S-PLE) and gas chromatography coupled to tandem mass spectrometry (GC-MS/MS) quantification, [PERSON] et al. [46] examined the presence of eight PBDEs and six NBFRs in biosolids samples from 15 wastewater treatment plants (WWTPs) in Western Australia. The extraction was followed by clean-up in a column containing Florisil and acidified silica eluted with 50:50 hexane/DCM, and reconstitution solvent was iso-octane and toluene (80:20). The result showed recovery values in the range of (80-120)% and LOQ values in the range of 0.03-120 ug/kg dw.