Content determination of malic acid and lactic acid in cider by HPLC

A method to detect malic acid and lactic acid contents of cider by HPLC that containing UV detector and Symmetry C18(3.5μm×4.6mm×75mm) column was established.The column temperature was 25℃, mobile phase consisted of methanol containing 0.1%formic acid,the rate of flowing was 0.5mL/min,detection wavelength was 210nm,the injection volume was 20μL.Malic acid and lactic acid contents were detected by external standard method.The analysis results showed that correlation coefficient of the linear equation was high(it was R~2=0.9969 for malic acid and R~2=0.9999 for lactic acid).The relative standard deviation(RSD) of retention time within one day was less than 0.12%and the RSD of the peak area within one day was less than 2%, RSD of retention time in different days was below 0.12%and the RSD of the peak area in different days was below 1.82%.For malic acid,the limit of detection(LOD) was 0.43mg/L(S/N≥3),the limit of quantity(LOQ) was 1.30mg/L(S/N≥10).For lactic acid,the LOD was 1.12mg/L and the LOQ was 3.36mg/L.It was a suitable way to determine malic acid and lactic acid contents of cider with great linear relationship,favorable reproducibility and high sensitivity.