DETERMINATION OF PROTOBERBERINE ALKALOIDS IN COPTIS CHINENSIS BY MICROEXTRACTION AND HIGH PERFORMANCE LIQUID CHROMATOGRAPHY

摘要

Sample preparation technique based on an organic filter membrane (pH-resolved filter membrane microextraction) (pH-RFMME) was developed, coupled with high-performance liquid chromatography, and used to determine protoberberine alkaloids (jatrorrhizine, epiberberine, coptisine, palmatine, and berberine) in Coptis chinensis at different pH values through a one-step procedure. This green procedure provides a desirable sample pretreatment technology. The main variables affecting the extraction such as filter membrane area (or volumes of extraction solvents), sample pH, eluent pH, ionic strength, extraction stirring rate, extraction time, and sample volume were optimized. Under the optimized conditions, the enrichment factors of the analytes were 40.4–52.0, the linear ranges were 3.2–6250 ng ·mL~(-1) for jatrorrhizine and epiberberine, 6.0–12000 ng ·mL~(-1) for coptisine, 1.8–3600 ng ·mL~(-1) for palmatine, and 18.8–18800 ng ·mL~(-1) for berberine, with r~2≥0.9945. The limits of detection were less than 0.3 ng ·mL~(-1). Satisfactory recoveries (84.8%–115.5%) and precision (1.8%–10.0%) were also achieved. These results confirmed that pH-RFMME is a simple, rapid, practical, and environmentally friendly method to isolate analytes that exhibit significant differences in acidity or alkalinity from complex samples.