Flow-injection determination of boric acid concentration with conductometric detection

Abstract

The flow-injection determination of boric acid with conductometric detection in technological environments of the primary circuit of WWER-type nuclear power plant is described. The method consists in periodical dosing a fixed sample volume into the flow of the mannitol solution. As a of the Formation of an anionic boric acid complex with mannitol and equivalent amount of hydroxonium ions, results in an abrupt increase in the electrical conductivity, which is recorded by a conductometric detector. The hydraulic and measuring circuits of the analyzer are implemented using standard ionochromatographic equipment. It is shown than in the concentration range of the analyte 1 – 16 g/liter, the correcting additives of ammonium and potassium hydroxides do not interfere with the results of the analysis. To eliminate the interfering effect of correcting additives at low concentrations of boric acid (0.2 – 1.0 g/liter) we propose to use a Donnan dialysis through a cation exchange membrane. Optimal conditions of the analysis are specified and the metrological characteristics are determined. At a concentration of boric acid of 0.2 g/liter, the standard deviation does not exceed 2%.