A novel hollow fiber/graphene oxide/solvent bar microextraction coupled with high performance liquid chromatography for preconcentration and determination of tanshinones and salvianolic acids in Radix Salvia miltiorrhiza
In this paper, a novel hollow fiber/graphene oxide/solvent bar microextraction (HF-GO-SBME) coupled with high-performance liquid chromatography was developed and introduced for simultaneous preconcentration and determination of lipid-soluble active ingredients including dihydrotanshinone I, cryptotanshinone, tanshinone I, and tanshinone IIA, as well as water-soluble salvianolic acid B, danshensu, and protocatechuic aldehyde in Radix Salvia miltiorrhiza. To evaluate the technique, seven compounds of varying polarity were used as model analytes, and a polyvinylidene fluoride hollow fiber of 1.0 cm filled with graphene oxide attached n-octanol was used as a microextraction bar. The extraction conditions, including the amount of graphene oxide, the type and amount of organic solvent, sample phase pH, salt concentration, agitation speed, extraction time, and sample phase volume, were investigated and optimized in detail. The solid–liquid synergistic microextraction mechanism of HF-GO-SBME was analyzed and verified. Under the most favorable conditions, the enrichment factors of the target analytes were 2.4–905, the limits of detection were below 0.92 ng mL−1, and the recoveries were between 84.5% and 107.5%. Thus, HF-GO-SBME is a simple, effective, low-cost, high enhancement factor and practical microextraction mode with a wide range of potential applications for extraction and preconcentration of trace analytes.