Rapid amperometric determination of H2O2 by a Pt nanoparticle/Vulcan XC72 composite-coated carbon paste electrode in disinfection and contact lens solutions

The presentwork describes the preparation of a simple, sensitive, and reliableH(2)O(2) sensor made fromcarbon paste surfacemodified with a composite of platinum nanoparticles (< 5 nm) on graphitized carbon (Pt-C, 10% Pt on Vulcan XC72) by simply dropcoating. The unmodified carbon paste electrode (CPE) and the modified one (Pt-C/CPE) were characterized by scanning electron microscopy in combination with energy- dispersive X-ray spectrometry and by cyclic voltammetry. The Pt-C/CPE showed remarkable electrocatalytic properties toward the electrochemical redox reaction of H2O2 compared to CPE in phosphate (0.1 mol dm(-3); pH 7.50) and acetate (0.1 mol dm(-3); pH 4.50) buffer supporting electrolytes. Amperometry of H2O2 in the concentration range from 0.15 to 1.45 mu g cm(-3) with the Pt- C/CPE showed acceptable linearity, while the obtained values of LOQs were 0.06 mu g cm(-3) (pH 7.50, working potential 0.20 V, stirred solution) and 0.10 mu g cm(-3) (pH 4.50, working potential 0.50 V). The proposed analytical methods were applied to the determination of the H2O2 content in commercially available personal care products: disinfection (pH 7.50) and contact lens cleaning (pH 4.50) solutions. In both cases, obtained amperometric results are in good agreement with those measured by the traditional spectrophotometric method and with H2O2 concentration declared by producers. The Pt- C/CPE was also tested for monitoring of the H2O2 residual concentration in contact lens solution during its neutralization/decomposition process by solid Pt catalyst. At 6 h of neutralization treatment, 24.68 mu g cm(-3) of the H2O2 was determined which is below allowed H2O2 concentration concerning the limit of eye irritation.