Analysis of powder mixtures with the help of abrasive stripping voltammetry and coulometry

Summary

Abrasive stripping voltammetry was applied to the quantitative analysis of the following powder mixtures: MnO₂-FeOOH, HgS-HgO, HgO-PbO. Therefore, μg-amounts of the powder mixture were transferred onto a solid electrode and the electrochemical response of the solid sample is recorded. The calibration was made by measuring the percentage peak height of each component taking the sum of peak currents of both components as 100%. The relative standard deviation ranges from 3 to 15%. A calibration-free method based on microcoulometric measurements can be used in the case of powder mixtures of AgCl-AgI. The integration of staircase voltammograms directly yields the charges required to reduce AgCl and AgI and thus also gives the ratio of both components. The relative standard deviation was ≈10%. Microcoulometric measurements gave evidence that, in abrasive stripping voltammetry, the amount of electroactive substance ranges between 10⁻¹² and 10⁻⁹ mole.