Accuracy of determination of biochemical oxygen demand in river waters: Analytical Quality Control in the Harmonised Monitoring Scheme

Abstract

The Department of the Environment in collaboration with the Reginald Water Authorities has initiated a Scheme for the Harmonised Monitoring of the Quality of Inland Fresh Waters in England and Wales. The Scottish Development Department has been closely associated with the development of this scheme, and has introduced a similar scheme in Scotland in collaboration with the River Purification Boards. To achieve the required comparability of results, each laboratory takes part in an analytical quality control (AQC) scheme; this work is co-ordinated by the Water Research Centre. The general approach adopted to AQC has already been described, and this paper presents the results of tests made on the determination of biochemical oxygen demand in river waters. Broadly, each of the 10 participating laboratories achieved total errors not greater than 1 mg l^–1 O₂. The need to define clearly the analytical procedure to achieve adequate comparability has been shown.