# 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  
Various methods such as LLE, SPE, and ASE are commonly employed for extracting BFRs from abiotic media like water, soil, sediment, dust, air, and food contact article samples. LLE involves partitioning BFRs between two immiscible solvents, while SPE utilizes solid-phase sorbents to selectively retain BFRs for subsequent elution. ASE offers automated extraction with elevated temperature and pressure, expediting the extraction process from solid samples like soil and sediment. BFRs are hydrophobic compounds, which indicates that they will have low solubility in water, and their levels in water, particularly in the dissolved phase, are expected to be very low as it is primarily governed by their water solubility. The hydrophobic nature of BFRs causes them to preferentially partition into organic phases, such as sediments, suspended particles, and organic matter, rather than remaining dissolved in water. This phenomenon is often described by the octanol-water partition coefficient (K\({}_{\text{ow}}\)), which quantifies the distribution of a compound between an organic solvent (octanol) and water. BFRs generally have high K\({}_{\text{ow}}\) values, indicating their propensity to partition into organic phases. Despite their low water solubility, monitoring and assessing BFR levels in water and aquatic ecosystems are essential for understanding their fate, transport, and potential impacts on environmental and human health. Techniques such as solid-phase extraction (SPE) [41], LLE [28; 42], and SPME [43] are commonly used to concentrate and extract BFRs from water samples for analysis. The simultaneous determination of ultra-trace TBBPA, tribromobiphenyl A (tri-BBPA), dibromobiphenyl A (di-BBPA), monobromobisphenol A (mono-BBPA), and bisphenol A (BPA) in Shuxi River water by solid phase extraction (SPE), and high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS), was developed by [PERSON] et al. [42]. The results showed recovery rates in water samples were over 80.28%. SPE was selected as the extraction method in the study because the sample could be completely concentrated and purified simultaneously. [PERSON] et al. [43] developed a method consisting of an online coupling of solid-phase microextraction and ultrahigh-resolution mass spectrometry for the rapid screening of eight PBDEs in water samples. The coupling of the SPME with ultrahigh-resolution mass spectrometry (UHRMS) was assisted by thermal desorption and solvent-assisted atmospheric pressure chemical ionization. The result showed limits of detection and quantification values ranging between 0.01-0.50 ng/mL and 0.05-4.00 ng/mL, respectively. The recoveries were 57.2-75.2% for quality control samples at spiking levels of 0.8-10 ng/mL (4-50 ng/mL for BDE209), with relative standard deviation less than 19.0%. This procedure was completed in 22 min, about 6 times faster than the routine workflow such as solid-phase extraction coupled with gas chromatography-mass spectrometry. The differences in recovery rates and detection limits among methods for extracting BFRs in water samples are influenced by several factors. Method-specific variables such as the choice of extraction technique, the optimization of extraction parameters, and sample preparation steps play a significant role. Sample matrix effects, including the composition of the water sample, the presence of organic matter, salinity, and interfering compounds, also affect these outcomes. Additionally, analytical considerations such as instrumental sensitivity, calibration methods, the use of internal standards, and thorough recovery studies are crucial. Understanding and optimizing these factors can improve the accuracy, precision, and sensitivity of studies of BFR in water. Depending on the soil's origin and the sampling technique used, soil samples may be pretreated by air drying, freeze drying, or mixing with anhydrous Na\({}_{2}\)SO\({}_{4}\) before drying.