A dynamic electromagnetic field assisted boronic acid-modified magnetic adsorbent on-line extraction of cis-diol-containing flavonoids from onion sample

For the isolation of flavonoids, a novel magnetic and efficient boronic acid (BA)-functionalized iron oxide particle was prepared and applied to a dynamic electromagnetic-field-assisted solid-phase extraction (DeMF-SPE) device. With the help of the dynamic electromagnetic field, it is possible to form a microcolumn with dynamic dispersion of boronic acid-modified magnetic sorbents. As the sample passes through the extraction region, the magnetic sorbent in its dynamic motion enables high-efficiency extraction through active and countless contacts with the target. Meanwhile, five flavonoids (quercetin (Qu), wogonoside (Wo), isoquercetin (Is), daidzin (Da), and baicalein (Ba)) were selected to investigate the selective entrapment of boronic acid modified magnetic particles during the DeMF-SPE process. Several parameters affecting adsorption and desorption conditions were investigated and optimized. Under optimal conditions, the DeMF-SPE–HPLC–MS/MS approach has a wide linear dynamic range and good linearity (R2 > 0.99), low detection limits (0.16–1.25 μg L–1), and satisfactory recovery (94.9–106.2%). The analytical method was applied to real samples and showed satisfactory adaptability. Therefore, dynamic electromagnetic field-assisted solid-phase extraction (DeMF-SPE) using the prepared magnetic particles can be considered an efficient and rapid analytical method for extracting flavonoids from onion samples.