Clinical application of liver diseases diagnosis using ultrahigh-sensitive liquid chromatography-mass spectrometry for sialic acids detection

•Ultrahigh-sensitive analysis of sialic acids by LC-MS was developed.•Girard's P reagent was firstly introduced for sialic acid derivatization in this method.•No matrix effect existed in the quantification of sialic acid in human serum.•FSA and TSA of serum could be applied as early diagnosis indicators for severe liver diseases (such as HCC or liver failure).