Electrocatalytic performance enhanced of the electrooxidation of gamma-hydroxybutyric acid (GHB) and ethanol on platinum nanoparticles surface. A contribution to the analytical determination of GHB in the presence of ethanol

Abstract

The electrooxidation of GHB and ethanol on a glassy carbon/platinum nanoparticles/polyvinyl alcohol modified electrode (GC/PtNPs/PVA) in weakly acidic medium has been investigated by cyclic voltammetry and chronoamperometry. The study with the concentration, the scan rate and the analyses of j-t curves at several potentials for both compounds showed an enhanced electrocatalytic performance on the GC/PtNPs/PVA electrode.Cyclic Voltammetry of ethanol-GHB mixtures was also performed observing that the presence of GHB in ethanol solutions significantly suppressed the oxidation peak currents of ethanol. This fact has been discussed in different experimental conditions and suggests that this behaviour is due to a competition of both alcohols for the active sites of the platinum surface according to a Langmuir-type expression. Depression of the current density of ethanol in the presence of GHB opens up new prospects for the development of strategies for the determination of GHB. The interval of detectable concentrations comprises between 1 and 75mM (0.125 and 9.15mg/mL) within the known toxic dose for GHB that is 0.5mg/mL (4mM). Detection limit of GHB, under these experimental conditions, was 0.872mM (0.110mg/mL). Analyses of test samples including typical recreational alcoholic beverages (vodka, lemonade+vodka, gin, rum, tequila and whisky) on the surface with the modified electrode have been successfully carried out. Precision (% RSD) values of alcoholic drinks and spiked GHB samples were tested in intra-assay and inter-assay.