Application of experimental design by differential pulse voltammetry for determination of rare elements as complexes with diethylenetriaminepentaacetic acid (Dtpa)

Abstract

Rare earth elements have been known as the importance material in modern technology. Since the presence of these materials in environment is very small concentration, the development method for fast and sensitive detection is challenging. Instead of relatively expensive ICP-MS instrument, the utilization of voltammetry method to answer the task of fast and sensitive detection is considerably cheaper. In the present work, a complex of Gadolinium (Gd) and Terbium (Tb) with diethylentriaminepentaacetic acid (DTPA) ligand was studied by experimental design to obtain the optimum condition detection of differential pulse voltammetry. The Plackett-Burman design was selected as the method. The positive response was optimized based on Box-Behnken. Optimum experimental condition was achieved by using scan rate of 0.05 Vs-1, amplitude pulse of 0.5489 V, ligand concentration of 267.67 mgL-1, pH of 5.15 and the electrolyte solution of ammonium chloride of 0.1 M. Under the optimum experimental condition, the precision and accuracy were found as 99.7% and 97.4% for Gd-DTPA; and 99.5% and 91.4% for Tb-DTPA. The detection limit and quantization limit values for Gd-DTPA were 27.11 mgL-1 and 92.33 mgL-1, respectively; and Tb-DTPA were 27.69 mgL-1 and 92.34 mgL-1, respectively.