Sensitive adsorptive stripping voltammetric method for determination of lead in water using multivariate analysis for...

A sensitive adsorptive cathodic stripping voltammetric (AdCSV) method is presented for direct determination of Pb(II) at nanomolar levels in water based on metal complexation with 2-acetylpyridine salicyloylhydrazone (2-APSH) and subsequent adsorptive deposition onto hanging mercury drop electrode (HMDE). The instrumental and chemical factors were optimized using exploratory (Plackett-Burman) and sequential (Simplex) designs. Under optimal conditions (pH 5.6, -0.552 V for deposition voltage, 0.0083 V for voltage step and 0.87 s for time interval for voltage step) a limit of detection of 0.17 nM was obtained and the relative standard deviation of five measurements of 17.3 nM was 1.20%. The voltammetric responses increased linearly with metal ion concentrations ranging from 2.4 to 145 nM. The method was free from interferences of inorganic salts and trace metals usually present in seawater. The proposed method was successfully validated using certified reference estuarine water (LGC 6016) with relative error of -2.15% and applied to real seawater samples (relative errors of -4.40% and +1.84%).