Effect of Silver Salt on the Determination of Chemical Oxygen Demand by Flow Injection Analysis

Abstract

Use of silver salt was examined to enhance reliability of the flow injection analysis (FIA) for the chemical oxygen demand with potassium permanganate (COD_FIA⋅Mn). To compare with CO_Dm based on a Japan Industrial Standard, pertinent operating conditions of the FIA were investigated for waste water samples by using D-glucose or lactose as a standard. It has turned out that the most reliable results could be obtained by adding O.05% of silver nitrate into the flow of acidic permanganate solution as a catalyst. Under the proposed conditions, chloride up to 1000 mg⋅l^-1 did not interfere with the determination. The newly proposed FIA method could be successfully applied to industrial waste water samples.