Fluorous derivatization combined with liquid chromatography/tandem mass spectrometry: a method for the selective and sensitive determination of sialic acids in biological samples

We have developed a novel method for selective and sensitive analysis of sialic acids (N‐acetylneuraminic, N‐glycolylneuraminic, and 2‐keto‐3‐deoxy‐D‐glycero‐D‐galactonononic acid) utilizing liquid chromatography/tandem mass spectrometry (LC/MS/MS) combined with a fluorous derivatization technique. In this method, the carboxylic groups in the sialic acids are derivatized via amidation with heptadecafluoroundecylamine, a commercially available perfluoroalkylamine reagent. This reaction proceeds rapidly and readily at room temperature in the presence of a condensation reagent. Subsequently, the derivatives are retained specifically on an LC column with a perfluoroalkyl stationary phase by means of a fluorophilic or 'fluorous' interaction, and detected by positive electrospray ionization MS/MS. The detection limits of the examined sialic acids are in the range of 60–750 amol on column. We show that the proposed method can be used to analyze trace amounts of sialic acids in biological samples. Copyright © 2010 John Wiley & Sons, Ltd.