A procedure is described for the volatilization of inorganic arsenic(III) and arsenic(V) as AsH3 and the absorption of AsH3 in a silver nitrate solution. For the absorption of AsH3, a specially designed glass cell has been used which cycles the absorption solution, utilizing the principle of a mammouth pump. In the adsorption solution, arsenic(III) is determined by differential-pulse voltammetry. The procedure is applicable in the concentration range from 1 Ã 10^{â 6} to 5 Ã 10^{â 5} mol l^{â 1}.