DETERMINATION OF URINARY OXALATE WITH OXALATE OXIDASE AND PEROXIDASE IMMOBILIZED ONTO GLASS-BEADS

We have reported the immmobilization of barley oxalate oxidase on to a lkylamine glass beads through glutaraldehyde coupling (Pundir, C. S., Satyapal and Kuchhat, N. K. (1993) Clinical Chemistry 39, 1750-1751). The present report describes the immobilization of commercially availa ble horseradish peroxidase on to zirconia-coated arylamine glass beads through diazotization and a new method for the discrete assay of urin ary oxalate using both immobilized oxalate oxidase and peroxidase, In the method, urinary oxalate is precipitated with CaCl2, redissolved in HCl and then assayed using immobilized enzymes, The oxalate in 24 h u rine samples from apparently healthy male adults was measured by this method and found to be in the range of 12.2-28.0 mg with a mean of 19. 8 mg. The percentage recovery of added oxalate (17.5 mg/l) was 96.7 +/ - 3.4 (mean +/- SD). The mean value of urinary oxalate by our method i s comparable with those obtained by the Sigma kit method. The cost of oxalate determination in 100 urine samples by the present method has b een compared with that of the Sigma kit method.