A green extraction method based on aqueous two-phase system for trace-level enrichment of multi-residue pesticides in traditional Chinese medicine prior to HPLC-MS/MS quantitative analysis

At present, the matrix interference in traditional Chinese medicine (TCM) is still a great challenge for multi-residue pesticides analysis. Herein, an alcohol/salt aqueous two-phase system (ATPS) based on n-propanol and (NH₄)₂SO₄ was developed by comparing the binodal curve phase diagrams and the extraction rates of pesticides. The specific extraction conditions, including the composition of the ATPS, temperature, pH, and extraction time were explored through single factor experiments, and subsequently optimized using orthogonal array design and response surface methodology. The optimal conditions for the (NH₄)₂SO₄/n-propanol ATPS extraction were determined to be: extraction time of 30 min, (NH₄)₂SO₄ concentration of 22 %, temperature of 62.07 °C, n-propanol concentration of 30.13 %, and pH value of 7.66. In addition, the HPLC-MS/MS quantitative analysis of 25 pesticides in TCMs (i.e., honeysuckle and lily) was accomplished with recovery rates ranging from 64.2 % to 117.1 %. Moreover, the greenness of this method was evaluated using an analytical greenness calculator, and compared with other extraction techniques. The results indicate that the developed method is simple, efficient, and environmentally friendly, capable of trace-level enriching and simultaneously detecting multi-residue pesticides in TCM.