Naked-eye determination of oxalate anion in aqueous solution with copper ion and pyrocatechol violet

Abstract

A novel strategy for the determination of oxalate anions was successfully established using a copper ion and pyrocatechol violet (PV) ensemble. The sensor ensemble can discriminate oxalate over other common anions including F⁻, Cl⁻, I⁻, Br⁻, HPO₄²⁻, PO₄³⁻, AcO⁻, CO₃²⁻, SO₄²⁻, ClO₄⁻, P₂O₇⁴⁻, S²⁻ (deposited by Ag⁺), CN⁻ (shielded by Fe³⁺) and can detect oxalate at low microgram levels in quasi-physiological aqueous solutions. The detection of the oxalate anion gives rise to a rapid observable visual color change from blue to yellow.