Direct determination of urinary oxalate by a continuous flow method.

A continuous flow method is described for estimation of urinary oxalate, using oxalate oxidase (EC 1.2.3.4) and ascorbate oxidase (EC 1.10.3.3) immobilised on the inner surface of O-alkylated nylon tubes. Linearity, precision, oxalate recovery, freedom from interference by other urinary substances, accuracy, specificity, absence of interaction between samples and correlation with an established enzymic method were all excellent. The method has advantages over other methods in terms of speed, ease of use and cost. As the immobilised enzyme system has been stable for 15 months the method is suitable for both research and routine use.