An enzymic method for the spectrophotometric determination of oxalic acid

A simple method is described for the measurement of urinary oxalate. Oxalate decarboxylase is coupled with NAD+ requiring formate dehydrogenase and the result recorded spectrophotometrically. Accurate determination can be carried out either on urine or a citrate extract or urine. Using the citrate extract procedure, the urinary samples can be stored for at least 3 months without any effect on the oxalate content.