Determination of germanium(IV) by catalytic cathodic stripping voltammetry

Germanium(IV) can be determined using adsorptive cathodic stripping voltammetry in the presence of 3,4-dihydroxybe-nzaldehyde (DHB). The sensitivity of the voltammetric technique was improved greatly by the addition of vanadium(IV) to the sample. The reduction current of the adsorbed germanium(IV)-DHB complex ion was measured by differential-pulse cathodic stripping voltammetry. The peak potential is at −0.47 V vs. AgAgCl. The effect of various parameters (ligand concentration, supporting electrolytic composition and concentration, concentration of V(IV) ion, pH, accumulation potential and collection time) on the response are discussed. The response was linearly related to the germanium(IV) concentration in the range 1 × 10−10 to 1 × 10−8 mol l−1 The limit of detection was 5 × 10−11 mol l−1 The relative standard deviation (at 1.2 × 10−9 mol l−1 germanium) is 3.7% (n = 8). Possible interferences are evaluated. The method was applied successfully to the determination of germanium in ore samples.