Simultaneous Determination of Six Trace Elements in Plant Medicines by Derivative Adsorption Waves in Conjunction with a Microwave Technique

Abstract

Complex adsorption waves of Cu(II), Pb(II), Cd(II), Ni(II), Co(II), and Zn(II) in substrate solution (pH=9.26) of diacetyldioxime‐ammonia‐ammonium chloride‐sodium citrate‐gelatin‐sodium sulfite were studied and a new method for determination of the six trace elements in aqueous solutions was developed. The results show that there are sensitive adsorption waves of Cu(II), Pb(II), Cd(II), Ni(II), Co(II), and Zn(II) complexes at about −0.45, −0.61,−0.78, −1.07, −1.23, and −1.38 V, respectively. The method is easy to operate and is able to determine these trace elements in aqueous solutions rapidly and simultaneously. When the signal‐to‐noise ratio equals 3, the detection limits of copper, lead, cadmium, nickel, cobalt, and zinc are 3.2×10−4, 4.8×10−3, 1.9×10−3, 1.7×10−5, 2.1×10−6, and 1.0×10−3 µg/cm3. Good linear relationships exist between the concentrations and the current peaks when copper, lead, cadmium, nickel, cobalt, and zinc concentrations are within 6.5×10−4∼100, 9.3×10−3∼10, 4.1×10−3∼10, 3.2×10−5∼10−1, 4.0×10−6∼10−2, and 2.1×10−3∼10 µg/cm3, respectively. In conjunction with a microwave assimilation technique, the method has been used in the rapid and simultaneous determination of these trace elements in some plant medicines with satisfactory results.