Fast determination of aristolochic acid I (AAI) in traditional Chinese medicine soup with magnetic solid-phase extraction by high performance liquid chromatography.

In this paper, a novel core-shell structure magnetic microsphere FeO@SiO-TPM@StVp(FeO@SiO-3-(trimethoxysilyl)propyl methacrylate@styrene and n-vinylpyrrolidone) was successfully synthesized and used as a magnetic solid-phase extraction adsorbent for extraction of aristolochic acid I (AAI) in traditional Chinese medicine soup. The prepared FeO@SiO-TPM@StVp was characterized by transmission electron microscopy (TEM), scanning electron microscopy (SEM), vibrating sample magnetometer (VSM) and Fourier-transform infrared spectroscopy (FT-IR). The microspheres have various advantages of excellent hydrophilicity and π-electron system, which is very suitable for determining target analytes followed by high performance liquid chromatography (HPLC). The main factors, including the pH of samples, amount of adsorbent, adsorption time, elution solvent and desorption time, were optimized. Under optimal conditions, the proposed method showed a wide linear range of 0.4-10 µg/mL and a good correlation coefficient (R = 0.9918). The pretreatment procedure was achieved within 10 min. The recoveries of aristolochic acid I in real samples range from 80.9% to 89.6% with relative standard deviations less than 4.9%, highlighting the accuracy of this method.