Often paints contain oils that bind together the components (pigments, fillers, etc) of the paint. Analysis of these oils requires derivatization, but which derivatization method is the best for a quantitative approach?

The work on this topic began with the need of our cultural heritage group to have a routine method for the determination of fatty acid composition of oils with gas chromatography (GC). The analysis of oils with GC requires derivatization and for this a wide variety of procedures have been applied. It turned out there are only few comparisons of derivatization methods in the literature and all are quite limited by scope. For that reason, it was decided to explore this important topic comprehensively and, importantly, in the terms of absolute (not relative) quantification.

A member of our group – PhD student Eliise Tammekivi – implemented four common and well-known derivatization procedures to perform the absolute quantification of fatty acids with GC-MS and GC-FID. The four compared derivatization methods were: (1) methylation with m-(-trifluoromethyl)phenyltrimethylammonium hydroxide (TMTFTH), (2) two-step derivatization with sodium ethoxide (NaOEt) and N,O-bis(trimethylsilyl)trifluoroacetamide (BSTFA), (3) two-step derivatization with KOH and BSTFA and (4) acid-catalyzed methylation (ACM).

This study has now been completed and the results have been published in the journal Analytical Methods by E. Tammekivi, S. Vahur, O. Kekišev, I. D. van der Werf, L. Toom, K. Herodes and I. Leito. In the publication, a comprehensive and wide-scale quantitative comparison of the four derivatization methods is presented. The results demonstrate that methylation with TMTFTH is the least work-intensive and most accurate derivatization method – both in terms of reproducibility and derivatization efficiency (yield).  For further information see: Analytical Methods, 2019, 11, 3514 – 3522