Simultaneous Determination of Lactic Acid and Methyl Lactate by Reversed-Phase High Performance Liquid Chromatography

During the research of the green chemical technique for conversion of lactic acid to methyl lactate,a new reversed-phase high performance liquid chromatographic(RP-HPLC) method was developed for the simultaneous determination of lactic acid and methyl lactate in the continuous esterification system in order to optimize the reaction conditions.The HPLC conditions were Prevail C18 column with a mixture of V(NaH_2PO_4/H_3PO_4 buffer(pH 2.0))∶V(methanol)=90∶10 as the mobile phase at a flow rate of 1.0 mL/min and with refractive index detector.The linear range of lactic acid and methyl lactate were both 0.2～20 μg.Recovery of lactic acid was 94.55%～106.94% with relative standard deviations 1.23%～2.01%(n=3).Recovery of methyl lactate was 91.03%～109.0% with relative standard deviations 1.25%～2.88%(n=3).This method is simple,rapid and accurate.