A New and Simple Method for the Simultaneous Determination of Fe, Cu, Pb, Zn, Bi Cr, Mo, Se, and Ni in Dried Red Grapes Using Differential Pulse Polarography

Dried grapes are consumed in Turkey in high quantities. It is a very important fruit because of its high content of vitamins and elements. A new and simple differential pulse polarographic (DPP) method for the trace element determination in dried grapes has been established. With this technique, it is possible to determine very low quantities of elements with high accuracy. The polarograms were taken in various electrolytes and pH values in the presence of digested grape sample. According to these results, nine trace element determinations were made in acetate, potassium carbonate, and ammonia electrolytes at various pH values, with or without EDTA depending to ions under consideration. It was possible to separate and determine Pb, Cu, and Cr simultaneously in potassium carbonate at pH 11 with only one sample addition. For separation and determination of Ni and Zn peaks, ammonia buffer, pH = 9.8, was found suitable. Simultaneous determination of Bi, Mo, and Fe could be made in HAc–NaAc buffer at about pH = 7 and in the presence of EDTA. Selenite could be determined in HAc–NaAc buffer from its hydrogen catalytic peak in the presence of Mo(VI).