Development and Validation of a GC-MS Method Based on Solid-Phase Extraction and Derivatization for Analysis of Free and Glucuronide-Conjugated Bisphenol F in Biological Samples.

Background: As one of the speculated bisphenols to replace bisphenol A (BPA), bisphenol F (BPF), naturally present in mustard, is structurally similar to BPA and may have similar estrogenic activity, but information on its toxicity is very limited compared to BPA.

Objective: In order to support the toxicology study of BPF at Heath Canada, a GC-MS method based on solid-phase extraction (SPE) and derivatization was developed for analysis of BPF in liver samples.

Methods: Samples were treated with β-glucuronidase to convert BPF glucuronide to free BPF for analysis of total BPF.

Results: The method was validated for free BPF at different spiking levels, and recoveries ranged from 90-97.5% with RSDs from 0.11-5.54%. The method was also validated for glucuronide-conjugated BPF at different spiking levels of BPF mono-β-D-glucuronide: recoveries ranged from 72.3-93.3% with RSDs from 1.7-8.94%. The method was used to analyze 60 liver tissue samples from rats dosed with BPF at different levels in a toxicology study. Free and glucuronide-conjugated BPF were not detected in any of the control samples, which were not dosed with BPF (average method detection limit: 0.31 ng/g) but detected in all the other liver tissue samples with levels increasing at higher doses. The percentage of glucuronide-conjugated BPF in total BPF varied among the liver samples, from as low as 9.8% to as high as 77.9%, indicating the importance of analyzing biological samples for BPF in both free and conjugated forms for total exposure.

Conclusion: A GC-MS method based on solid-phase extraction (SPE) and derivatization was developed for analysis of both free and glucuronide-conjugated BPF in liver samples. This method was validated not only for free BPF, but also for mono-β-D-glucuronide-conjugated BPF for the first time to confirm the efficiency of the deconjugation procedure with enzyme.

Highlights: This method can be adapted and applied for analysis of free and glucuronide-conjugated BPF in other biological samples with appropriate validation in target sample matrixes.