Voltammetric studies of glutathione transfer across arrays of liquid-liquid microinterfaces for sensing applications

The simple and facilitated transfer of tripeptide glutathione across the water/2-nitrophenyl octhyl ether interface was studied via cyclic voltammetry at interface between two immiscible electrolyte solutions (ITIES). The micro-perforated membrane prepared with a laser with a femtosecond pulse was used for mechanical stabilization of the interface. The method of cyclic voltammetry was used to study the passive and facilitated interfacial transfer of glutathione and its complex with the crown ether dibenzo-18-crown-6 (DB18C6).The glutathione mass transfer mechanism was established and substantiated, the diffusion coefficients, thermodynamic characteristics of interphase transfer and the constant of complexation of the glutathione by DB18C6 were determined. Square wave voltammetry based on facilitated transfer was used for more accurate and sensitive determination of glutathione low detection limit (0.8 mu M) with wide linear dynamic range (from 3.0 to 80 mu M) was reached. The influence of various potentially interfering ions on the voltammetric determination of glutathione has also been investigated. The method developed was applied to determine glutathione in aqueous solutions and malt extract.