Analytical applications of oxocarbons. Part 3. Specific spectrophotometric determination of oxalic acid by dissociation of the zirconium( IV )–chloranilate complex

Oxalic acid can be determined spectrophotometrically, as it dissociates the chloranilate complex of zirconium(IV) at pH 2. The decrease in the absorbance at 335 nm is proportional to the amount of oxalic acid present. Optimum conditions for the method are described. The sensitivity of the method is high, allowing the determination of 0.035 ppm of oxalic acid. Because of the very high stabilities of the zirconium(IV) complexes of chloranilate or oxalate, few compounds interfere, particularly hydroxy acids. D-Glucose and alditols did not interfere, which could be useful in studies on solutions of biological interest.