Improved Extraction and Detection Method for Bisphenols Using Stable Isotope Labeling Technique

A pair of permanently positively charged stable isotope labeling (SIL) agents, 2-(4-(((2,5-dioxopyrrolidin-1-yl)oxy)carbonyl)phenyl)-1,3-dimethyl-benzimidazolium iodides (d 0 -DPDBM) and its deuterated counterpart d 6 -DPDBM, were designed and synthesized for the analysis of bisphenols with the aid of ultra-high-performance liquid chromatography-tandem mass spectrometry (UHPLC–MS/MS). The UHPLC–MS/MS sensitivity of bisphenols was enhanced due to the introduction of positively charged DPDBM moiety into the molecules. Bisphenols were purified by a simple n-hexane extraction and subsequent alkaline back-extraction method, which could remove both hydrophilic and hydrophobic matrices. Matrix effect was effectively minimized by this strategy and the SIL strategy during which samples and standards experienced identical ionization process. The developed method was applied to the simultaneous determination of bisphenols in food and food contact materials with limits of detection (LODs) of 1.5–6.5 ng·L −1 , and the limits of quantitation (LOQs) of 4.9 − 21.5 ng·L −1 . Correlation coefficients for all analytes were higher than 0.9964. The intra-day precision for all analytes was in the range of 2.7–4.1%, whereas the inter-day precision was in the range of 4.6–6.3%. The recoveries were in the range of 90.2 − 96.4%, and the matrix effects for all analytes ranged from –5.6 to 4.5%.