Voltammetric determination of ultra-trace total mercury and toxic metals in meals

This paper reports the sequential voltammetric determination of Hg(II) and Cu(II) at the gold electrode (GE), and of Cu(II), Pb(II), Cd(II), Zn(II) at the hanging mercury drop electrode (HMDE) by square wave anodic stripping voltammetry (SWASV). Determination was performed in matrices involved in food chain as wholemeal, wheat and maize meal, using 0.01 mol/L EDTA-Na2 + 0.06 mol/L NaCl + 2.0 mol/L HClO4 as supporting electrolyte. The analytical procedure was validated by the analysis of the standard reference materials Wholemeal BCR-CRM 189, Wheat Flour NIST-SRM 1567a and Rice Flour NIST-SRM 1568a. For all the elements, precision as repeatability, expressed as relative standard deviation (sr) was of the order of 3–5%, while trueness, expressed as relative error (e) was of the order of 3–7%. Once set up on the standard reference materials, the analytical procedure was transferred and applied to commercial meals sampled on the market for sale.