Comparative Studies of the Determination of Divalent Cadmium, Lead and Copper in the Boiling Medicinal Herbs by Stripping Voltammetry and by Atomic Absorption Spectrometry

Abstract

Cadmium, lead and copper were determined in ten Libyian boiling medicinal herbs samples by differential pulse anodic stripping voltammetry as well as by atomic absorption spectrometry. Voltammetric method was done at Hanging Mercury Dropping Electrode (HMDE) in Briton-Robinson buffer solution of pH ~2.1 at 25± 0.1°C. The sample preparation was carried out by boiling 2.0g of a finely pulverized plant sample for 10 min, cooled, filtered and completed to 50 mL measuring flask by deionized water. The optimal preconcentration potentials and times for the detection of these metal ions in all sample solutions have been studied. The concentration of each metal ion was determined by the standard addition method. The statistical parameters i.e. slope, standard deviation, correlation coefficient and confidence have been calculated. The levels of Cd(II), Pb(II) and Cu(II) ranged from 0.006-0.103, 0.205-1.751 and 0.198-2.124 µg g^-1 respectively. Copper was determined by Flame Atomic Absorption Spectrometry (FAAS) and the mean level was ranged from 0.202-2.010 µg g⁻¹ . On the other hand the mean levels obtained for determination of cadmium and lead by Graphite Furnace Atomic Absorption Spectrometry (GFAAS) ranged from 0.006 to 0.085 and from 0.220-1.850 µg g^-1 respectively.