An adsorbent of molecularly imprinted polymer incorporating graphene quantum dots to extract and determine bisphenols in soft drinks and milk

A highly selective magnetic composite adsorbent composed of graphene quantum dots (GQDs) and molecularly imprinted polymer (MIP) was fabricated and applied for the extraction and quantification of three bisphenols in soft drink and milk samples. Magnetite nanoparticles incorporated into the MIP enabled the adsorbent to be isolated from the sample solution with a magnet. The extraction efficiency toward target bisphenols was enhanced by the selective recognition sites of the MIP layer and also the abundant adsorption sites in GQDs. In the optimum condition, the composite adsorbent coupled with high-performance liquid chromatography (HPLC) exhibited linearity in the range of 10.0–200.0 µg L⁻¹. The limit of detection was 3.0 µg L⁻¹ while the limit of quantification was 10.0 µg L⁻¹. Applied to determine bisphenols in real samples, the proposed method achieved relative recoveries from 84.3 % to 94.9 % with relative standard deviations (RSDs) of less than 7 %. The proposed method is simple, rapid, efficient and accurate. The adsorbent can be reused for up to four extraction and desorption cycles, thus reducing the cost of analysis.