Dispersive micro-solid phase extraction of bisphenol A from milk using magnetic nylon 6 composite and its final determination by HPLC-UV

Herein, a new method for the determination of bisphenol A (BPA) in milk samples is presented. This method comprises a precipitation process, bearing in mind that the analyte has a high tendency to interact with the fatty compounds of the milk, and a magnetic micro-solid phase extraction prior to the determination by high-performance liquid chromatography with UV detection. The presented precipitation process combines EDTA-McIlvaine buffer (the common precipitation agent) with acetonitrile to facilitate the transference of the analyte to the supernatant (only the 30% is transferred in the absence of acetonitrile). The employed sorbent, a magnetic nanoparticles-nylon 6 composite, was synthesized in a quick and one-step method, and was also characterized by several instrumental techniques (SEM, TEM, FT-IR, and SQUID). The developed methodology provides a limit of detection of 3.05 μg/L, which is in accordance with the specific migration limit (SML) established by the European Union. The repeatability of the method, in terms of relative standard deviation, was better than 9.1% (at 100 μg/L) and 16.8% (at 25 μg/L). The recovery study provided values in the range from 86 ± 7 to 99 ± 5%.