Magnetic Solid Phase Extraction-HPLC Determination of Rhodamine B in Wine

The sample solution (pH 4.0, 10 mL) was extracted with homemade magnetic graphene (CoFe₂O₄-G) of 20 mg at the flow rate of 1.0 mL·min^-1, and acetone of 1 mL was used as the eluent. Rhodamine B in the above solution was determined by HPLC. Linear relationship between peak area and mass concentration of rhodamine B was found in the range of 0.50-10 μg·L^-1, with detection limit (3S/N) of 0.08 μg·L^-1. Test for recovery was made by standard addition method, giving results in the range of 99.0%-101%, with RSDs (n=11) ranged from 1.6% to 4.0%.