Application of Plackett-Burman and Box-Behnken experimental designs in differential voltammetry for determining Gadolinium concentration

Middle group rare earth elements, such as Gadolinium, have an important role in a variety of applications, mostly used in high-tech industries because they have good mechanical strength. However, the rare earth elements of this middle group are difficult in their analysis because each element has almost the same physical and chemical properties. Gadolinium is one of the rare earth elements that have high paramagnetic properties. The purpose of this study was to determine the gadolinium content by differential pulse voltammetry using an experimental design. Plackett-Burman experimental design was used to obtain selected factors that have positive results to the method. A total of 11 factors that have the potential as the main influence in this study were selected at the highest (+) and lowest (-) levels, and then measured 12 times according to the Plackett-Burman experimental design. Furthermore, optimization was carried out with the Box-Behnken experimental design by performing 15 measurements to obtain the optimum conditions for each factor. Response data was processed and obtained factors with optimum conditions, deposition potential of -2.0 V, modulation of the amplitude of 0.1 V, and a deposition time of 120 seconds. The detection limit and the quantitation limit were 3.97 mg/L and 10.71 mg/L, respectively. The recovery of Gadolinium was 95%, which is satisfactory. (paper)