Comparison of performances and analytical applications of two immobilized oxalate oxidase sensors

The enzyme oxalate oxidase was immobilized on a pre-activated Nylon membrane or on a collagen membrane after activation of the carboxyl groups with the aid of an acyl-azide reaction. Oxalate was quantitated amperometrically via electrooxidation of the hydrogen peroxide generated in the reaction between oxalic acid and oxygen. The specific activities for the collagen and Nylon membranes were 0.13 and 0.74 Ucm2, respectively. The enzyme activities for the two membranes were determined as a function of pH and ionic strength. The detection limits of oxalate were 1 × 10−5 M for the collagen sensor and 4 × 10−7 M for the Nylon sensor.