Construction of dissolved O₂ metric oxalate biosensor using PVC membrane bound sorghum leaf oxalate oxidase

Abstract

A portable dissolved oxygen (DO) meter based oxalate biosensor has been constructed by mounting a polyvinyl chloride (PVC) membrane bound sorghum leaf oxalate oxidase on sensing part of combined electrode of an aqualytic DO meter. Biosensor showed optimum activity within 10-12 s at pH 5.0 and 30°C. A linear relationship was observed between oxalate conc. and O₂ consumption [1.0-10 μM (low conc. range), 0.1-1.0 mM (high conc. range)]. Biosensor gave mean value of oxalic acid in urine [22.5 mg/l in males (n=6) and 19.3 mg/l in females (n=6)], and in serum [3.2μM/l in males (n=6) and 2.9 μM/l in females (n=6)]. Biosensor is unaffected by physiological concentrations of Cl^- and NO₃^-.