Column-free matrix solid-phase dispersion extraction based on cucurbit[8]uril used for the determination of the flavonoid content in Oroxylum indicum (L.) Vent.

A simple, rapid and environmental method named column-free matrix solid-phase dispersion (FMSPD) has been investigated for the extraction of three flavonoids (oroxin A, oroxin B and baicalein) from the seeds of Oroxylum indicum (L.) Vent. In this study, cucurbit[8]uril was used as the sorbent of FMSPD to selectively extract three flavonoid compounds and transferred them into an aqueous solution for direct determination using HPLC-UV based on the recognition interaction of cucurbit[8]uril toward the compounds. The variables that influenced the extraction efficiency were investigated, which include the amount of cucurbit[8]uril, grinding time, volume of water, and pH of the solution. A good linearity was exhibited with correlation coefficients > 0.9991 for all three flavonoids. The intra- and inter-day precisions were 1.7–2.6% and 3.1–5.5%, respectively, and the limit of detection was between 0.1 and 0.18 μg mL–1. The recoveries ranged from 90.8% to 101.4%, with relative standard deviations of 2.9–6.8% under the optimized conditions. The developed method was applied to analyze four kinds of Semen Oroxyli from different regions of China. F- and t-tests showed that the results had no significant difference when comparing the traditional ultrasound-assisted extraction method to the novel FMSPD extraction method, but the method was simpler, faster and did not use organic solvents.