# Chemicals from Brominated Flame Retardants: Analytical Methods, Occurrence, Transport and Risks
## 2 Analytical Methods for the Detection of BFRs in Environmental and Biological Samples
### Air Samples  
Sampling methods for BFRs in outdoor air requires various techniques to collect air samples effectively for subsequent analysis. Major studies on BFRs in air that have been reported in the literature are performed using passive and active air techniques. Active air samplers offer precise control over sampling parameters and higher sampling rates, making them suitable for short-term or real-time monitoring; passive air samplers, on the other hand, are simpler, more cost-effective, and better suited for long-term monitoring or integrated sampling over extended periods. More often-used passive air samplers include polyurethane foam (PUF) Figure 1. and Glass Fiber Filters (GFFs). After air sampling for BFRs analysis, the collected samples need to undergo extraction to isolate and concentrate the BFRs from the sampling medium prior to analyses. The extraction method used depends on the nature of the BFRs and the sampling medium. Some common extraction methods include UAE or Soxllet extraction ([PERSON] et al., 2018), SPE ([PERSON] et al., 2018), and PLE ([PERSON] et al., 2018). The choice of extraction method for BFRs in air samples should be based on the specific analytical requirements, including the need for precision, time constraints, and budget considerations. Each method offers distinct benefits and trade-offs which have been described in sections above, and selecting the most appropriate technique will depend on balancing these factors to achieve optimal results. [PERSON] et al. (2018) identified and quantified the indoor levels of 41 legacy and novel FRs, which include 20 OPFRs and 21 HFRs (8 PBDEs, 3 HBCDDs, 5 NBFRs, and 5 DECs). The passive air sampling method employed PUF and GFFs for the collection of the contaminated air samples. Extraction was achieved with n-hexane/acetone (1:1, _v/v_) in an ultrasonic bath and dried under a gentle stream of nitrogen before the reconstitution with 5 mL of n-hexane. The extraction Clean-up was achieved by solid phase extraction (SPE) and eluted with hexane:DCM (1:2 _v/v_). Finally, samples were dried with a stream of nitrogen and reconstituted with 40 \(\mu\)L of toluene, then subjected to GC-EI-MS-MS and LC-MS/MS quantification. The results from the study showed recoveries of (41 and 119%), and LOQ values ranged from (2-86) pg/m\({}^{3}\). The occurrence and carcinogenic potential of airborne PBDD/Fs and PCDD/Fs around a large-scale municipal solid waste incinerator were investigated by [PERSON] et al. [54]. The air samples were collected using PUF, and the samples ultrasonically extracted with 30 mL dichloromethane. Sample clean-up was carried out by sequential purification through an acid silica gel bed, a multi-layer silica column, and a Florisil column and a Trace GC Ultra gas chromatograph coupled to a DFS magnetic sector mass spectrometer were employed for the quantification [54]. The recovery recorded from the study was between 38 and 128%. Further details are presented in Table 1.  
Figure 1: The passive air sampling device (**A**) and polyurethane foam disk (**B**) used in the study and the schemes of the device assembling (**C**) and passive air sampling principle (**D**); data are from [54]. \begin{table}
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