Determination of glutathione in baker's yeast by capillary electrophoresis using methyl propiolate as derivatizing reagent

• Methylpropiolate for derivatization of thiols in CE.
• First application of methylpropiolate in CE.
• Determination of glutathione in baker's yeasts.

In this study we demonstrate – for the first time – the suitability of methyl propiolate – an alkylester of propiolic acid – as a thiol derivatizing reagent for capillary electrophoresis. Glutathione (as analyte in yeast samples) and N-acetylcysteine (as internal standard) were selected as model compounds. Several parameters affecting the separation efficiency (buffer pH, concentration, and separation voltage) and the derivatization yield (pH, reaction time and reagent concentration) were thoroughly investigated. Validation was carried out towards the determination of glutathione in commercially available yeast samples. The LOD was 1.5 μmol L−1 and the linearity was obeyed in the range of 25–200 μmol L−1. The accuracy in terms of recoveries ranged between 95.9% and 113.6%. The approach proved to be free from matrix effects, while the results were confirmed by a corroborative method based on liquid chromatography coupled to post-column derivatization.