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DOI: 10.1055/s-0032-1321195
Mutual interference problems in the simultaneous voltammetric determination of ultra-trace total mercury(ii) and toxic metals in medicinal herbs matrices
The work describes the the voltammetric determination of mercury (II), copper (II), lead (II), cadmium (II), zinc (II) by square wave anodic stripping voltammetry (SWASV) in medicinal herbs. The digestion of each matrix was carried out using a concentrated HCl-HNO3-H2SO4 acidic attack mixture. 0.01 mol/L EDTA-Na2 + 0.06 mol/L NaCl + 2.0 mol/L HClO4 was employed as the supporting electrolyte. The voltammetric measurements were carried out using a conventional three electrode cell, employing, as working electrodes, a gold electrode (GE) and a stationary hanging mercury drop electrode (HMDE). The analytical procedure has been verified on the standard reference materials Spinach Leaves NIST-SRM 1570a, Tomato Leaves NIST-SRM 1573a and Apple Leaves NIST-SRM 1515. For all the elements, the precision as repeatability, expressed as relative standard deviation (sr) was of the order of 3–6%, while the accuracy, expressed as relative error (e) was of the order of 3–7%. Once set up on the standard reference materials, the analytical procedure was applied to commercial medicinal herbs samples.
A critical comparison with spectroscopic measurements is also discussed.