Potential confounders of bisphenol-a analysis in dental materials

• A cured experimental dental resin was analyzed for extractable bisphenol A (BPA).
• Extracted BPA appeared ∼30-fold higher when quantified by LC/UV vs LC/MS/MS.
• LC/UV results reflect confounding by a co-eluting EDMAB contaminant or derivative.
• Use of LC/MS/MS enables accurate and unequivocal identification of extracted BPA.

ObjectivesIn the published literature, a variety of analytical methods have been used to quantify and report bisphenol A (BPA) release from dental resins. The objective of this study was to compare results obtained for quantification of BPA in dental resin extracts using an LC/UV analytical method and an LC/MS/MS method.MethodsA cured Bis-GMA-based resin representative of commercial dental products was extracted according to ISO 10993 guidelines for medical devices. d16BPA was included as an internal standard. Sample processing followed expert recommendations for minimizing BPA sample contamination. Extracts were separated using HPLC methods and analyzed for BPA using LC/UV and LC/MS/MS detection methods.ResultsThe reported BPA concentrations were about 30-fold higher using LC/UV vs. LC/MS/MS. Full scan LC/MS/MS in both positive and negative modes showed that the apparent high BPA values seen with LC/UV were caused by co-elution of a previously unidentified chemical, thought to arise from one of the polymerization initiators.SignificanceThese results emphasize the potential difficulties in obtaining accurate analyses of BPA in complex mixtures such as dental resins and their extracts. Both good separation methodology and a detection method with high specificity and sensitivity are important to avoid incorrect identification of extractables, and consequent incorrect quantitative assignments for species of interest. Reliable methods are essential for accurate estimation of patient exposure to BPA and development of meaningful health risk assessments.