A Novel Green Sample Pretreatment Method Column-Free Matrix Solid-Phase Dispersion Extraction: Application in a High-Performance Liquid Chromatography Experiment for Undergraduate Chemistry

Here, we describe a student experiment that uses a novel column-free matrix solid-phase dispersion (FMSPD) extraction combined with high-performance liquid chromatography (HPLC) for quantitative determination of oroxin A (OA) and oroxin B (OB) from Semen Oroxyli (the seeds of Oroxylum indicum (L.) Vent.). Compared with traditional sample pretreatment methods, which are time-consuming and complex and use a large amount of organic solvents, the new FMSPD method is fast, safe, simple, and easy to operate. It does not use organic solvents and is convenient for undergraduate teaching experiments. By comparing retention times of the OA and OB standards at the same chromatographic conditions, students were able to identify these two components present in Semen Oroxyli and to quantify their contents using calibration curves of OA and OB. In addition, the same Semen Oroxyli sample was extracted using the traditional ultrasonic-assisted extraction method reported in the literature and determined using HPLC. Any significant difference between the two methods was evaluated using F- and t-test statistical methods. The results indicated that the new sample preparation can be used instead of the traditional ultrasonic-assisted extraction method. The experiment provides an opportuni students to be exposed to a new extraction technique to enrich their horizons. At the same time, students can learn some new theoretical knowledge such as solubilization, host-guest interaction, and inclusion complexes while also consolidating their learning of the key theoretical concepts including the liquid chromatography separation mechanism, sample preparation and cleanup method for complex samples, and statistical analysis of the data.