A recommended molybdenum-blue procedure for the determination of arsenic in steel

Abstract

A recent molybdenum-blue procedure suggested by Nall for the determination of arsenic in steel has been modified to give quantitative extraction of arsenic from the steel solution.

The new procedure differs from that of Nall in that reduction of arsenic in the solution of the steel is effected with tin(II) chloride instead of with copper(I) chloride and hypophosphorous acid, and arsenic(III) is extracted as the iodide rather than as the chloride. Recoveries of arsenic of greater than 95 per cent. were obtained consistently with the recommended procedure, which gives high precision and good reproducibility from day to day. Results in close agreement with the certified values, with relative standard deviations of less than 2 per cent., were obtained for the analysis of nine British Chemical Standards steel samples.

An extension of this procedure is also described in which the molybdenum blue is extracted into 1 + 4 v/v hexanol-3-methylbutan-1-ol, giving a five-fold increase in sensitivity.