One step salting-out assisted liquid-liquid extraction followed by UHPLC-ESI-MS/MS for the analysis of isoflavones in soy milk

We developed and validated a fast UHPLC-ESI-MS/MS in combination with one step salting-out assisted liquid-liquid extraction (SALLE) for high throughput analysis of 12 isoflavones in soy milks. Conventional sample preparation requires two steps composing time-consuming freeze-drying (72 h) and solvent extraction (2 h). The SALLE required only about 40 min, which was over 100 times faster without compromising the extraction efficiency. The baseline separation of 12 isoflavones was achieved in 2.5 min by the UHPLC-MS/MS which is the fastest chromatographic method ever reported. The new method was fast, simple, selective, sensitive, precise and accurate. The method was successfully applied to 22 commercial soy milks for the high throughput analysis of isoflavones. The new method would be a fast, simple, reliable, and useful measure for the analysis of isoflavones in soy milk especially in the laboratories facing the challenges of saving the analytical time, labor cost and solvent usage. (C) 2017 Elsevier Ltd. All rights reserved.