Dispersive Micro Solid-Phase Extraction with Graphene Oxide for the Determination of Phenolic Compounds in Dietary Supplements by Ultra High Performance Liquid Chromatography Coupled with Quadrupole Time-of-Flight Tandem Mass Spectrometry

This report described the use of graphite oxide (GO) as sorbent in dispersive micro solid-phase extraction (DMSPE), together with ultra high performance liquid chromatography coupled with quadrupole time-of-flight tandem mass spectrometry (UHPLC-Q-TOF/MS), for the determination of phenolic compounds (protocatechuic aldehyde, caffeic acid, and rosmarinic acid) in dietary supplements. The extraction conditions such as sample agitation, agitation time, sorbent amount, and type and volume of the eluent were optimized. The results showed that GO-assisted DMSPE exhibited higher enrichment factors for tested solutes as compared to the normal extraction. Under the most favorable conditions, good limits of detection (0.07-0.21 ng/mL) and repeatability of extraction (RSDs below 5.6 %, n = 5) were obtained. The developed method was applied to determine phenolic analytes with satisfactory recoveries, which were 90.1-96.4 % for Danshen and 85.5-97.6 % for Danshen injection, respectively.