An alternative approach for quantification of glyceraldehyde and dihydroxyacetone as trimethylsilyl derivatives by GC-FID

A method for quantification of glyceraldehyde (GA), dihydroxyacetone (DHA) and glycerol (GLY) by gas chromatography coupled to a flame ionization detector (GC-FID) involving one-step derivatization into trimethylsilyl ethers is presented. In pyridine, DHA and GA showed predominant peaks assigned to dimeric structures and smaller peaks corresponding to the monomers. The later were identified by GC-MS as their completely derivatized molecules and were useful for construction of calibration curves with high linear correlation. On the other hand, DHA dimers were completely dissociated in water but GA dimers remained whereas with both, intermediates peaks arose which were associated to hydrated trymethyil silyl species. A calibration approach involving the sum of areas of most relevant peaks associated to aqueous solutions of GA and DHA was developed. Replicates measurements of a problem solution were in accordance with the results obtained by a well stablished HPLC technique. The coefficient of variation was below 5% for GLY and below 12% for GA and DHA. Compared with the HPLC method, the new GC-FID method presented a similar limit of quantification in the case of GA whereas for GLY and DHA a one-order-of-magnitude increase of sensitivity was achieved. TMS derivatives of GA and DHA without prior oximation enable a useful technique to study the equilibrium of the different tautomeric forms in solution.