Electrochemical determination of free and total glutathione in human saliva samples

Glutathione (GSH) is a small peptide of great relevance in many biological processes. Its determination is a valuable aid to understand the cellular health status. Important information is obtained not only from the quantification of its free reduced form (GSH) but also of its oxidized form (GSSG) and both the ratio and absolute amounts of these two species. We report an electro-analytical methodology for determining the reduced and total GSH using square wave voltammetry and a screen-printed electrode modified with carbon nanotubes (CNT-SPE). For the total glutathione determination, sodium borohydride was chosen as a reducing agent for its effectiveness and inert electrochemical activity. Human saliva samples were successfully analysed by the developed methodology as a proof-of-concept and validated independently with a commercially available enzyme assay kit. (C) 2015 Elsevier B.V. All rights reserved.