A new procedure for the determination of mercury(II), copper(II), lead(II), cadmium(II) and zinc(II) traces in food matrices by square wave anodic stripping voltammetry and standard addition method is proposed. A rapid, inexpensive and multi-analyte analytical method suitable for food safety control is provided. Comestible vegetables were chosen as samples. A two-step, sequential determination was defined, employing two working electrodes: a gold electrode (GE) for mercury(II) and copper(II), and subsequently a hanging mercury drop electrode (HMDE) for copper(II), lead(II), cadmium(II) and zinc(II). No sample pre-treatment was needed. Spinach leaves, tomato leaves and apple leaves were employed as standard reference materials to optimize and defined the analytical procedure. The new method shows good selectivity, sensitivity, detectability and accuracy. A critical comparison with spectroscopic measurements is discussed. Spinach, lettuce and tomato samples sold on the market were analysed as real samples. Lead(II) and cadmium(II) concentration exceeded the relevant legal limits. [...]
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The present work reports the critical comparison about the employment of three different supporting electrolytes (0.1 mol L−1 HClO4, 0.01 mol L−1 EDTA-Na2 + 0.06 mol L−1 NaCl + 2.0 mol L−1 HClO4 and 0.1 mol L−1 KSCN + 0.001 mol L−1 HClO4) and their instrumental and chemical optimisation for the simultaneous voltammetric determination of total mercury(II) and copper(II) in sediments and sea water at gold electrode, especially discussing the reciprocal interference problems. The differential pulse anodic stripping voltammetric (DPASV) measurements were carried out using a conventional three-electrode cell: a gold electrode (GE) as working electrode, a platinum wire and an Ag‖AgCl‖KClsat as auxiliary and reference electrodes, respectively. The analytical procedure was verified by the analysis of standard reference materials: Estuarine Sediment BCR-CRM 277, River Sediment BCR-CRM 320 and Mercury in Water NIST-SRM 1641d. Once set up on the standard reference materials, the analytical procedure was transferred and applied to sediments and sea waters sampled in a lagoon ecosystem connected with Adriatic Sea (Ravenna area, Italy).
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