Accuracy of determination of chloride in river waters: Analytical Quality Control in the Harmonised Monitoring Scheme
The Department of the Environment, in collaboration with the Regional 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 introduced a similar scheme in Scotland in collaboration with the Scottish River Purification Boards. To achieve the required comparability of results from all laboratories involved, 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 been described, and this paper presents the tests made and results obtained in the determination of chloride in river waters. Broadly, each of the ten participating laboratories achieved total errors not greater than ±20% of the chloride concentration for concentrations greater than 5 mg l–1 of chloride.