Determination of EDTA species in water by square-wave voltammetry using a chitosan-coated glassy carbon electrode

The electrochemical behavior of Fe(EDTA)-/2- on a chitosan-coated glassy carbon electrode (GCE) and the determining method of the EDTA species in water samples by square-wave voltammetry (SWV) have been investigated. Fe(EDTA)- can be adsorbed on the positively charged chitosan membrane assembled on a GCE and be reduced at a potential of –0.095 V vs. Ag/AgCl. On the chitosan-coated GCE, the cathodic stripping peak current is proportional to the concentration of EDTA after the operating parameters of SWV were optimized. The measuring range of EDTA was from 2.0×10^-6 to 8.0×10^-5 mol/L with a correlation coefficient of r=0.998 and a detection limit of 2.0×10^-7 mol/L. The relative standard deviation was less than 6.4% (n=5) and the recovery was in the range of 98–105% for the determination of practical samples. The result was consistent with that from the HPLC method.