It is widely recognised that, unless special steps are taken, analytical results from a group of laboratories engaged in a monitoring programme are likely to be of poor comparability. This in turn can prejudice the conclusions drawn from the results of monitoring. On the basis of previous studies, the problem is known to be particularly acute for measurements of trace metals in saline waters.
Recognising the difficulty, the Marine Pollution Monitoring Management Group (MPMMG) and the Water Research centre (WRc) have organised a programme of Analytical Quality Control (AQC). This has the objective of ensuring that analytical results for filterable cadmium and mercury in saline waters, obtained by water industry and other relevant laboratories, are of adequate accuracy and comparability for their intended uses. WRc is to coordinate a series of tests, some involving distributions of standards and samples, which the participating laboratories undertake; this series of tests, the background to the approach and some of the results obtained to date are described here.
