Effervescence-Enhanced Microextraction Based on Acidic Ionic Liquids and In Situ Metathesis Reaction for Bisphenol Detection in Milk Samples

Herein, we developed an effervescent reaction-enhanced dispersive liquid–liquid microextraction method for the preconcentration/extraction of bisphenols (BPs) in milk and milky tea samples. This microextraction method was based on the utilization of acidic ionic liquid (AIL) and in situ metathesis reaction (AI-EDLM). Compared to the traditional imidazolium-based ionic liquid, AIL can not only be used as an extractant, but also as an acidic source in the effervescent reaction. Under such a case, it can avoid the use of additional acidic source and also achieve a rapid dispersion effect due to vigorous CO 2 bubbles, which simplify the experimental procedures and decrease the preparation cost of effervescent tablets. By employing the one-factor-at-a-time approach, the main parameters were optimized as follows: 400 mg of [BMIM][HSO 4 ] as extractant, 100 mg of Na 2 CO 3 as alkaline source, 400 mg of Li[NTf] 2 as the ionic-exchange reagent, 4% of NaCl, 5 min of centrifugation and 1.5 mL of ether as the elution solvent. Under optimized conditions, the limits of detection ranged from 0.12 to 0.32 μg L −1 , and the extraction recoveries for BPA, BPB, and BPAF spanned the range of 85.7–106.2% in five kinds of milk samples. Therefore, the AIL ([BMIM][HSO 4 ]) played dual roles, i.e., extractant and pH regulator, in the AI-EDLM procedures. Overall, this proposed method is simple, quick, and environment-friendly with low detection limits and high recoveries for BPs, and thus has excellent application value in the sample pretreatment field in milk and milky tea samples.