Development of a liquid chromatography/atmospheric pressure photo‐ionization high‐resolution mass spectrometry analytical method for the simultaneous determination of polybrominated diphenyl ethers and their metabolites: application to BDE‐47 metabolism in human hepatocytes

Abstract

Polybrominated diphenyl ethers (PBDEs) are flame retardants widely used in electronic and domestic goods. These persistent pollutants are present in the environment and in humans, and their toxicological properties are of growing concern. PBDEs can be metabolised into compounds suspected to be responsible for their toxicity. These metabolites have been characterised quite well in rodents and fish, but available information in humans remains scarce. For their identification, an efficient method for the simultaneous analysis of PBDEs, hydroxylated PBDEs (OH-PBDEs), and other PBDE metabolites in a single run was needed and has been developed in this work. Atmospheric pressure ionisation modes were compared, and Atmospheric Pressure Photo-Ionization (APPI) was selected. After careful setting of APPI parameters such as dopant and operating temperature, the optimised method was based on APPI ionization coupled to High-Resolution Mass Spectrometry operating in the full scan mode at a resolution of 60 000. This provided excellent sensitivity and specificity, allowing the discrimination of signals which could not be resolved on a triple quadrupole used as a reference. The full-scan high-resolution acquisition mode allowed monitoring of both parent PBDEs and their metabolites, including hydroxylated PBDEs, with detection limits ranging from 0.1 pg to 4.5 pg injected on-column based on the investigated standard compounds. The method was applied to the study of BDE-47 metabolism after incubation with human primary cultures of hepatocytes, and proved to be efficient not only for monitoring the parent compound and expected hydroxylated metabolites, but also for the identification of other non-targeted metabolites. In addition to hydroxy-BDE-47, several conjugated metabolites could be located, and the formation of a dihydrodiol derivative was evidenced for the first time in the case of PBDEs in this work.

Maternal transfer of BDE-47 to offspring and neurobehavioral development in C57BL/6J mice

“…Specifically, the Barnes spatial maze was used to evaluate spatial learning, and it was used because it does not require swimming and avoids associated stress produced by water immersion. Similar to our earlier findings in the MWM [40], BDE-47 exposed mice showed altered performance in the Barnes spatial maze. However, while performance in the Barnes maze was impaired in all BDE-47 exposure groups in the present study (i.e., longer escape latency and longer distance traveled), performance of exposed mice in the MWM in our earlier study appeared to be better than controls (i.e., shorter swim distance to locate the submerged escape platform).…”

“…It should be noted that there is only one published study in the US that reported levels of BDE-47 in human fat and data from this study, therefore, may not accurately represent the degree of accumulation in human fat tissues [30]. Furthermore, metabolism of BDE-47 is higher in humans [39,76] when compared to mice [58,59] and this may explain in part why levels of the parent compound, BDE-47, are substantially higher in mouse tissue samples, and in particular fat, when compared to human data. However additional studies measuring BDE-47 levels in human fat should be carried out because while BDE-47 may be less biologically active when sequestered in fat, it appears to be readily mobilized into milk which may put the developing infant at risk [49].…”

“…In the studies by Eriksson et al male NMRI mice were used, and previous work indicates that this strain of mice shows increased cognitive impairment and decreased in spontaneous activity and exploration with increasing age [40]. Therefore the results from the Eriksson et al study which demonstrated a lack of habituation to a novel environment following an acute exposure to BDE-47 could be due in part to their choice of mouse strain and age of testing.…”

Cytochrome P450 3A1 Mediates 2,2′,4,4′-Tetrabromodiphenyl Ether-Induced Reduction of Spermatogenesis in Adult Rats

“…OH-BDEs have been detected in bile, urine, and feces in rats and mice treated with BDE47 [11] and in blood samples from women and children who were environmentally exposed to PBDEs [12]. The formation of OH-BDEs of BDE47 and BDE99 by rat and human hepatic cells and microsomes has been reported [13], [14], [15]. More recently, OH-BDEs have been regarded as a relatively new group of phenolic compounds that have attracted particular interest because of their biological effects, including disruption of thyroid hormone homeostasis and sex hormone steroidogenesis, which might mediate PBDE-induced reproductive toxicity [16], [17].…”

Mimicking of Estradiol Binding by Flame Retardants and Their Metabolites: A Crystallographic Analysis

“…The role of BFRs as endocrine disruptors might be further pronounced because of contribution of their metabolites/analogs, which have been previously detected in various species (Fini et al 2012; Hakk et al 2000; Schauer et al 2006; Shen et al 2012; Zalko et al 2006). Hydroxylated metabolites of BDE-47 have been detected in incubations with rat microsomes (Hamers et al 2008) and human hepatocytes (Marteau et al 2012), as well as in fetal and maternal blood samples (Qiu et al 2009). One of the metabolites detected by Hamers et al (2008) and Qiu et al (2009) was 3-hydroxy-2,2´,4,4´-tetrabromodiphenyl ether (3-OH-BDE-47).…”