Disposable electrochemical sensor for rapid determination of Cd, Cu, Pb and Hg in fish by square wave anodic stripping voltammetry

To allow efficient control both in fish, simple, fast and reliable analytic protocols are the most suitable choice for heavy metals determination. In fact conventional approaches are unsuitable for on-site screening since related instrumentation is not portable and requires skilled personnel and long analysis times. Electrochemical-based approaches, i.e., stripping analysis using conventional electrodes although allowing fast analysis of heavy metals, employs instrumentation still intended for laboratory use and thus unsuitable for on-site heavy metal analysis. More recently, stripping analysis can be performed by pocket-size portable electrochemical analyzers coupled to disposable screen-printed electrodes (SPE). An optimized fast digestion method coupled to electrochemical detection to monitor Pb, Cu, Cd and Hg in fish tissues was developed. Square wave anodic stripping voltammetry (SWASV) coupled to disposable SPE was employed as fast and sensitive electroanalytical method for metals detection. Different approaches in digestion protocols were assessed. Among the different tested methods, best results were obtained by digesting fish tissue with hydrogen peroxide/hydrochloric acid mixture coupled with solid phase purification of the digested material. Sensitive, reproducible, fast multi-analyte detection of for Pb, Cd, Cu and Hg in Atlantic hake fillets by SWASV has been achieved. Validation of the method in the fish matrix was performed with CRMs (DORM-2 and NIST 2977). Extension of this fast, simple, sensitive and cheap approach for heavy metal analysis to other food tissue matrices can be foreseen. The portability of the instrumentation together with fast and simple sample pre-treatment makes this approach particularly appealing for on-site, multi-analytes detection.