Abstract

Sensitive voltammetric determination of copper in three leafy vegetables using screen printed graphite electrode modified with thin mercury film

Author(s): Ruuta Tekeraoi, Rajendra Prasad

A thin mercury film electrode was fabricated by in situ electrodeposition over screen printed graphite electrode.Aparaffin oil paste of 15%HgCl2 in graphite (w/w) was used for the purpose. Copper(II) in acetic acid buffer showed two anodic striping peaks at -0.238 and -0.108VversusAg/AgCl, of which the peak current for the first peak showed linear concentration dependence. Electrode was used in the determination of copper in three leafy vegetables, viz. cabbage (Brassica rapa L. ssp. Chinensis), lettuce (Lactuca sativa) and tabua (Amaranthus gangeticus). The results of these determinations were found to be consistent with that obtained from standard AAS method. Cabbage and lettuce were found to contain 4.49 and 3.41 ppm of copper of the dry weight of the leaf, whereas tabua leaves contained signigicantly low amount, i.e. 0.31 ppm of the dry weight. Sensitivity and accuracy of the method were found to be comparable to that of standard atomic absorption spectrophotometric (AAS) determinations of copper. Anodic stripping voltammetry (ASV) is known for simultaneous determination of two or metal ions in small volume samples. Coupled with low cost and portability of the instrument,ASV could successfully be employed as a versatile method in the reliable determination of copper and other metals in food and vegetable samples, particularly in the small island countries.