Determination of trace heavy metals in milk using an ionic liquid and bismuth oxide nanoparticles modified carbon paste electrode

A novel carbon composite electrode modified with bismuth oxide nanoparticles and the ionic liquid n-octylpyridinium hexafluorophosphate was fabricated and used to simultaneously determine cadmium and lead levels using square wave anodic stripping voltammetry. This electrode combines the unique advantages of nanomaterials and ionic liquid with the low cost and easy fabrication of the carbon composite electrode. Compared with the traditional binder based composite electrode, our electrode exhibited well-defined and separate stripping voltammetrie peaks for cadmium and lead. Furthermore, the antifouling capacity of the bismuth film electrode was significantly improved by the ionic liquid. Under optimized conditions, the linear range of the composite electrode was from 3.0 to 30.0 μg L^-1 for both metal ions with a detection limit of 0.15 μg L^-1 for cadmium and 0.21μg L^-1 for lead. Trial milk sample analyses showed that the modified electrode was sensitive, reliable and effective for the determination of trace heavy metals, holding great promise for routine analysis applications.