Simultaneous determination of nine flavonoids in Polygonum hydropiper L. samples using nanomagnetic powder three-phase hollow fibre-based liquid-phase microextraction combined with ultrahigh performance liquid chromatography-mass spectrometry

A simple, inexpensive, and efficient nanomagnetic powder three-phase hollow fibre-based liquid-phase microextraction (HF-LPME) technique combined with ultrahigh performance liquid chromatography–mass spectrometry (UPLC–MS) was developed for the simultaneous analysis of nine flavonoids in Polygonum hydropiper L. samples. The final, optimised extraction conditions were as follows: an organic solvent of ethyl acetate, a donor phase of aqueous KH₂PO₄ at pH 3.0, an acceptor phase of aqueous NaHCO₃ at pH 8.5, a stirring rate of 1000 rpm, and an extraction time of 50 min. Under these conditions, analyte calibration curves were all linear, with correlation coefficients ≥0.9994. The relative standard deviation for all analytes in intra-day (0.8–2.2%) and inter-day (1.7–3.5%) precision tests was well within the acceptable ranges, as were the limits of quantitation (LOQ < 0.054 μg/L) and detection (LOD < 0.170 μg/L). Recoveries for all standard compounds were between 95.17% and 99.82%, with a RSD of no more than 2.3%. Correlative analyses demonstrated that the physicochemical parameters of the compounds themselves also influenced the extraction efficiency. This technology proved to be rapid, sensitive, and reliable for the quality control of P. hydropiper L. samples.