Solid-State Voltammetric Determination of Gaseous Hydrogen Peroxide Using Nanostructured Silica as the Electrolyte

Abstract

By a base-catalyzed sol-gel process, solids were prepared that extracted hydrogen peroxide from the gas phase and served as electrolytes for the voltammetric oxidation of HO2− in the absence of a contacting liquid phase. A combination of a 60-min preconcentration by solid-phase extraction into the pore water of the xerogel and differential pulse voltammetry provided a detection limit of 10.2 ppbv H2O2. The linear least squares calibration plot parameters over the range 96–5400 ppbv were: slope 58.5 nA(ppmv)−1; intercept −1.70 nA; and r 0.999. The sensitivity was increased by including Triton X-114 well-above its critical micelle concentration and 1.3 M MgCl2 in the sol. The former is known to provide domains that serve as templates for obtaining nanoporous silica, and the latter acts as an internal humidistat that controls the pore water of the resulting xerogel in the 50 % (by weight) range.