Issue 17, 2015

Elucidation of several neglected reactions in the GC–MS identification of sialic acids as heptafluorobutyrates calls for an urgent reassessment of previous claims

Abstract

The current analytical protocol used for the GC–MS determination of free or 1,7-lactonized natural sialic acids (Sias), as heptafluorobutyrates, overlooks several transformations. Using authentic reference standards and by combining GC–MS and NMR analyses, flaws in the analytical protocol were pinpointed and elucidated, thus establishing the scope and limitations of the method. It was demonstrated that (a) Sias 1,7-lactones, even if present in biological samples, decompose under the acidic hydrolysis conditions used for their release; (b) Sias 1,7-lactones are unpredicted artifacts, accidentally generated from their parent acids; (c) the N-acetyl group is quantitatively exchanged with that of the derivatizing perfluorinated anhydride; (d) the partial or complete failure of the Sias esterification-step with diazomethane leads to the incorrect quantification and structure attribution of all free Sias. While these findings prompt an urgent correction and improvement of the current analytical protocol, they could be instrumental for a critical revision of many incorrect claims reported in the literature.

Graphical abstract: Elucidation of several neglected reactions in the GC–MS identification of sialic acids as heptafluorobutyrates calls for an urgent reassessment of previous claims

Supplementary files

Article information

Article type
Paper
Submitted
14 Jan 2015
Accepted
17 Mar 2015
First published
17 Mar 2015

Org. Biomol. Chem., 2015,13, 4931-4939

Elucidation of several neglected reactions in the GC–MS identification of sialic acids as heptafluorobutyrates calls for an urgent reassessment of previous claims

P. Rota, L. Anastasia and P. Allevi, Org. Biomol. Chem., 2015, 13, 4931 DOI: 10.1039/C5OB00081E

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