Tetrabromobisphenol A (TBBPA) is the most abundant brominated flame retardant (BFR) currently used in plastic polymers, electronic appliances and entertainment equipments (Okeke et al., 2022; Xie et al., 2020). Bisphenol A (BPA) is a major industry product widely used in resins and poly-carbonate plastics (Staples et al., 1998; Xie et al., 2020). TBBPA may degrade to less brominated compounds and bisphenol A through pyrolysis, chemical reaction, microbial degradation and biological metabolism (Liu et al., 2019; Arbeli et al., 2006; Liu et al., 2016). Due to their wide application and higher persistence, TBBPA and BPA have been detected in various environmental matrices and biological samples including air, dust, surface water, wastewater, sediment, soil, sewage sludge and aquatic organism (Han et al., 2013; Xie et al., 2020; Pan et al., 2022; Liu et al, 2016), however, very fewer data are available for plant samples, relatively. TBBPA and BPA, as a kind of typical endocrine disruptors, can pose potential threat to human and wildlife even in environmental relevant dosage (Covaci, A. et al., 2009; Pan et al., 2022; Liu et al, 2016; Wu et al., 2021). They both show toxic effects on plants by inhibiting the seed germination and causing lipid per-oxidation of plants (Dogan et al., 2010.). Moreover, BPA exhibits more toxic effects than TBBPA as to seed germination and oxidative stress (Dogan et al., 2010).
Plants exhibit essential roles in the translocation and transformation of organic compounds. Plant uptake of organic contaminant is a significant process associating with its ecology risk, environmental fate and the potential threat to the food chain (Collins et al., 2006; Wang et al., 2011). The ability of plants to absorb organic pollutants is a central process in biogeochemical cycling, which increases the risk of human exposure to them through the food chain (Collins et al., 2006). Understanding the behaviors of TBBPA and its derivatives in intact plants will help to elucidate its environmental behaviors. The metabolism of persistent organic pollutants is an important factor in determining their bioaccumulation, fate, and potential toxicity (Hakk et al., 2003). TBBPA could be reductively dehalogenated to bisphenol A (BPA) in slurry of anaerobic sediment (Ronen et al., 2000; Arbeli et al., 2003). For biotic experiment, tribromobisphenol A was found in the rat liver and was excreted into the feces via bile when TBBPA was administered to adult female Wistar rats (Hakk et al., 2003). Dehalogenation was observed in plants for other brominated flame retardants, such as polybrominated diphenyl ethers (Zhao et al., 2012; Wang et al., 2011; Huang et al., 2010). Previous studies have reported that uptake of TBBPA by plant root systems and the resulting translocation to the aboveground part by active transport through the vascular network is common in plants (Li et al., 2011). The previous study presented that derivatives of TBBPA including TriBBPA, as well as DBBPA, MBBPA and BPA, are more toxic than TBBPA from the microtox and algal assay (Debenest et al., 2010). Meanwhile, the effects of molecular species in different pH conditions on the uptake of TBBPA on plant are still unknown. Therefore, it is necessary to investigate metabolism derivatives of TBBPA in plants in different pH conditions.
There is a lack of information concerning the analysis and concentration of TBBPA in plant sample relatively, which need strict extraction and purification procedure due to the complicate lipid components of the plant sample. There have been many methods reported to date for determining TBBPA and its metabolisms in various samples (Covaci, et al., 2009; Okeke et al., 2022, Environmental Research), such as gas chromatography mass spectrometry (GC/MS), liquid chromatography-electrospray tandem mass spectrometry LC/MS(/MS)(Tolosa et al., 2021; Sánchez-Brunete et al.,2005; Okeke et al., 2022). Although LC/MS/MS exhibits higher sensitivity and better detection limits, GC/MS is more available with lower cost in the analysis laboratory. Moreover, the deficiency could be remedied by optimize the clean-up procedures in reduce the matrices effects. Therefore, the objectives of this study were to develop an analytical method for simultaneous determination of TBBPA and BPA in plant sample, including the improvement and optimization for the extraction and cleanup procedures. Then, the new developed method was applied to investigate the uptake and the effects of pH on the uptake of TBBPA in maize, which is regarded as a model plant to investigate the fates of persist organic compounds because of its extensive cultivation. Here, hydroponic exposures were adopted to focus on the plant metabolism of TBBPA without parallel soil microorganism interactions. Finally, the possible metabolites of TBBPA in maize were identified by GC-MS. This study will be helpful to assess the ecological risk of TBBPA in food chain, analyze its environmental behaviors and broaden the knowledge of its environmental fates comprehensively.