SOLID-STATE VOLTAMMETRIC DETERMINATION OF GASEOUS-HYDROGEN PEROXIDE USING NANOSTRUCTURED SILICA AS THE ELECTROLYTE

By a base-catalyzed sol-gel process, solids were prepared that extract ed hydrogen peroxide from the gas phase and served as electrolytes for the voltammetric oxidation of HO2- in the absence of a contacting liq uid phase. A combination of a 60-min preconcentration by solid-phase e xtraction into the pore water of the xerogel and differential pulse vo ltammetry provided a detection limit of 10.2 ppbv H2O2 The linear leas t squares calibration plot parameters over the range 95-5400 ppbv were : slope 58.5 nA(ppmv)(-1); intercept -1.70nA; and r 0.999. The sensiti vity was increased by including Triton X-114 well-above its critical m icelle concentration and 1.3 M MgCl2 in the sol. The former is known t o provide domains that serve as templates for obtaining nanoporous sil ica, and the latter acts as an internal humidistat that controls the p ore water of the resulting xerogel in the 50% (by weight) range.