Chronoamperometric determination of lead ions using PEDOT:PSS modified carbon electrodes

A new simple chronoamperometry methodology was developed for the ultrasensitive determination of lead ions using a PEDOT:PSS coated graphite carbon electrode. The polymer was directly coated on a graphite carbon electrode and characterized using simple cycle voltammetric measurements. The presence of lead ions induced a cathodic peak starting at −550 ± 10 mV vs. Ag/AgCl, and an anodic peak starting at −360 ± 10 mV vs. Ag/AgCl. Electroaccumulation of lead ions onto the PEDOT:PSS modified electrode was performed at −650 mV vs. Ag/AgCl for 30 s in a pH 2.2 hydrochloric acid solution. Chronoamperometry measurements were carried out at −350 mV vs. Ag/AgCl allowing the oxidation of accumulated lead. Using this method, lead ions were detected for concentrations ranging between 2.0 nmol L⁻¹ and 0.1 μmol L⁻¹ (R² = 0.999). The detection limit was calculated to be 0.19 nmol L⁻¹ and the quantification limit of 0.63 nmol L⁻¹. The method was shown to be highly precise and sensitive, negligible interference was detected from other metal ions. The proposed method was successfully applied for the detection of lead ions in vegetables.