Measurement methods and problems in the reproduction of mass concentrations of total and free chlorine in natural and industrial water media

Industrial and other sites, in which the mass concentration of total and free active chlorine must be monitored in natural and industrial water media, are indicated. The creation of reference working standards reproducing the size of the mass concentration unit of total and free chlorine is needed for assurance of measurement uniformity. Features of measurement methods and the reproduction of this unit are examined.