Kinetic Spectrophotometric Method for the Determination of Trace Amounts of Oxalate by an Activation Effect

A new, simple and inexpensive kinetic catalytic spectrophotometric method for the determination of oxalate is described. The method is based on an activation effect of oxalate on a catalytic effect of iron(II) on the oxidation of iodide by bromate. The reaction is monitored by measuring the absorbance of triiodide ion at λmax = 352 nm. A calibration graph was obtained from 0.10 - 7.0 µg cm-3 of oxalate with a detection limit of 0.080 µg cm-3. The standard deviations for ten replicate determinations of 0.50, 1.0 and 5.0 µg cm-3 of oxalate were 4.0, 2.6 and 1.8%, respectively. The applicability of the method was demonstrated by the determination of oxalate ion in real samples.