METHOD OF INVERSION-VOLT-AMPEROMETRIC DETERMINATION OF HETEROVALENT ARSENIC FORMS IN AQUEOUS SOLUTIONS Russian patent published in 1998 - IPC

FIELD: analytical chemistry. SUBSTANCE: method is based on electroaccumulation of As (III) on stationary mercury electrode in the presence of ions Cu²⁺ followed by recording curve of cathode reduction of concentrated copper arsenide. Method involves determination of As (III) content at background of 0.6 M HCl + 0.04 M N₂H₄ HCl + 50 mg/l Cu²⁺ by height of inversion cathode peak at potential (-0.72) V, chemical reduction of As (V) to As (III), measurement of total water-soluble content of arsenic and determination of As (V) content by concentration difference of total and trivalent arsenic. Method involves additional addition of HCl, KJ and Cu²⁺ to solution where As (III) content has been determined, Chemical reduction of As (V) to As (III) is carried out in background electrolyte which has the following components: 5.5 M HCl + 0.1 M KJ + 0.02 M N₂H₄ 2 HCl + 100 mg/l Cu²⁺. Electroaccumulation of arsenic is carried out at potential (-0.55 ± 0.01) V, cathode volt-ampere curve is recorded at the range of voltage from (-0.55) V to (-1.0) V and total arsenic content in solution is determined by height of inversion peak at potential (-0.76 ± 0.01) V. EFFECT: improved method of determination. 8 dwg