Determination of sialic acid in dietary supplement by liquid chromatography tandem-mass spectrometry (LC-MS/MS)

Simultaneous determination of sialic acids (N-acetyl neuraminic acid - NANA and N-glycolyl neuraminic acid - NGNA) in dietary supplement matrices by liquid chromatography tandem-mass spectrometry (LC-MS/MS) had been developed. Sialic acids were separated by using a C18 column (75 mm x 3.9 mm, 2.5 µm) and isocratic mobile phase of acid formic 0.1 %: acetonitrile (80:20, v/v). Sialic acids were totally hydrolyzed by formic acid 1M at 80oC in 2 hours before being analyzed by LC-MS/MS. It was proved that the method with the linearity range of 0.04 - 4.25 µg/ml had highly specificity, selectivity, repeatability, and recovery rate, that well satisfied AOAC requirements. The method has been applied to detect sialic acids in commercial dietary supplements.