Accuracy of determination of trace concentrations of dissolved cadmium in river waters: Analytical Quality Control in the Harmonised Monitoring Scheme

Abstract

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 been closely associated with the development of this Scheme, and has introduced a similar scheme in Scotland in collaboration with the River Purification Boards. A programme of Analytical Quality Control (AQC) has been designed to ensure laboratories achieve the required comparability of results. In work on the determination of cadmium, it has not been possible to adhere to the recommended programme of AQC. An assessment of the comparability of laboratories' analytical results for the determination of dissolved cadmium in river water is presented. The accuracy requirements for this determinand (that the total error on a single result should be not larger than 0.1 µg l^–1 or 20% of sample concentration, whichever is the greater) was not achieved by participating laboratories.