Evaluation of trace heavy metal levels in soil samples using an ionic liquid modified carbon paste electrode.

An ionic liquid n-octylpyridinium hexafluorophosphate (OPFP) modified carbon paste electrode was developed. This ionic liquid modified carbon electrode showed better electrochemical activities compared with the traditional carbon paste electrode which employed the paraffin oil as the binder. With the electrochemically deposited bismuth film, the developed electrode exhibited well-defined and separate stripping voltammetric peaks for cadmium and lead. The linear range of the bismuth film electrode was from 1.0 μg L(-1) to 100.0 μg L(-1) for both metal ions with a deposition time of 120 s and a deposition potential of -1.2 V in pH 4.5 acetate buffer solution. The detection limit was 0.10 μg L(-1) for cadmium and 0.12 μg L(-1) for lead with a deposition time of 180 s. The electrode was also applied to determine cadmium and lead in soil sample extracts. Results suggested that the proposed electrode was sensitive, reliable and effective for the determination of trace heavy metals.