DETERMINATION OF GALLIUM BY SQUARE-WAVE VOLTAMMETRY ANODIC-STRIPPING,BASED ON THE ELECTROCATALYTIC ACTION OF 2,2'-BIPYRIDINE IN DIMETHYLSULFOXIDE - COMPARISON WITH AN AQUEOUS NASCN NACLO4 ELECTROLYTE/

Deposition potential, deposition time, square-wave frequency, 2,2'-bip yridine concentration, and gallium concentration have been studied in detail, for the determination of trace concentration levels of the met al by square-wave voltammetry anodic stripping analysis, in dimethylsu lphoxide. Optimum conditions have been found for gallium(III) determin ation and results compared to those obtained in 0.5 M NaSCN + 4.2M NaC lO4 aqueous electrolyte by obtaining calibration graphs for the range 1 x 10(-8) x 10(-5) gallium. Accuracy (+/- 3%) and precision (4-6% SD) of this method were assessed with both 4 x 10(-8) M and 4 x 10(-7) M gallium solutions used as synthetic samples. The efficiency of solvent extraction of gallium with di-isopropyl ether was found to be 99.98% at a 4 x 10(-7) M gallium concentration. The proposed method was appli ed to the determination of the gallium content in rock mineral samples (using the above mentioned solvent extraction procedure), and results compared to those obtained with the NaSCN-NaClO4 based electrolyte. N o statistically significant difference was observed. Analytical proced ures followed are given in detail.