Determination of Bisphenols in Tea Infusion Samples Using a Three-Phase Solvent Bar Microextraction Based on a Deep Eutectic Solvent Followed by Ultra-High-Performance Liquid Chromatography with Fluorescence Detection

This paper describes a simple and sensitive method for determining the content of five bisphenols at the µg L−1 level in tea infusion samples. The procedure uses a polypropylene hollow fiber filled with a deep eutectic solvent as the acceptor phase and 1-octanol as the supported liquid membrane, and the optimal conditions for the three-phase stir bar microextraction method were established as follows: a menthol–octanoic acid mixture (1:1 molar ratio) as the hollow-fiber filling, an extraction time of 1 h, and 80 µL of methanol for analyte desorption. The method demonstrated good linearity over the ranges of 1.5–30.0 µg L−1 (BPF, BPA, BPAF, and BADGE) and 6.0–120.0 µg L−1 (BPZ), with limits of detection between 0.28 and 1.01 µg L−1, and the relative recovery values were satisfactory (99–120%) with acceptable precision (RSD < 17%). Thus, the method was successfully applied to quantitatively analyze twenty commercial tea infusions, in which BPF was detected at concentrations above the LOQ, and the greenness and overall applicability of the approach were confirmed using the AGREEprep and BAGI assessment tools.