Determination of Poly(malic acid) in Fermentation Broth by RP-HPLC

For the detection of poly(malic acid) fermentation broth,a reversed phase high performance liquid chromatography method was developed.The samples was analyzed on a column of AlltimaTM C18(4.6 mm×150 mm,4 μm) with a mixture of acetonitrile and 0.025 mol/L KH2PO4 buffer(pH 2.5)(5:95,v:v) used as mobile phase at the flow rate of 1.0mL/min.The detection wavelength was 210 nm;the column temperature was 25 ℃ and the volum of injection was 5 μL.Before sampling,the fermentation broth was centrifuged to remove fungis,added with organic solvent to remove polysaccharide and hydrolysed.L-malic acid were completely separated and determined in 3 minutes.The recovery and relative standard deviation(RSD,n=3) of L-malic acid by RP-HPLC method were 98.70%~100.65%,and 0.40%~1.11%,respectively.The recovery and relative standard deviation(RSD,n=3) of L-malic acid by L-malic acid kit were 96.70%~97.23% and 0.57%-1.19%,respectively.The method was proved to be a effective way to determine the poly(malic acid) in fermentation broth.