CO-ORDINATION OF ANALYTICAL QUALITY CONTROL FOR DOE HARMONISED MONITORING SCHEME Final Contract Report to the Department of the Environment, covering the period 1974-1984
Report No DWI0224

Aug 1984

SUMMARY

This report summarises the progress made on the contract over the period 1974-1984.

The objective of the work has been to ensure that the analytical results obtained by different laboratories in the Harmonised Monitoring Scheme for River Water Quality are adequately comparable for their intended use. The report describes briefly the approach adopted for collaborative Analytical Quality Control to achieve this objective, and illustrates the results obtained for all the determinands examined in tests of inter-laboratory bias.

The AQC scheme has been successful in allowing the achievement of the required comparability of analytical results for the following determinands; chloride, ammoniacal nitrogen, total oxidised nitrogen (TON) nitrite-nitrogen, suspended solids, BOD (ATU), pH and electrical conductivity. In the case of the trace metals cadmium, copper, lead, mercury, nickel and zinc, the required degree of comparability has, however, not been achieved.

Reasons for the failure to attain the required comparability of analytical results for these determinands are considered, as are also reasons for the poorer progress than was originally expected. It is concluded that detailed re-assessment of the trace metals methods used by participating laboratories, and of their application, is necessary to determine the sources of bias and to rectify them. It is also concluded that progress has been impeded by the lack of well-tested methods for trace metals at the start of the work, and by the limited effort for the work available in participating laboratories. The technical approach to AQC adopted is, however, adjudged to have been successful.

Recommendations are made concerning the conduct of any future Analytical Quality Control work for national river water monitoring.

Copies of this report may be available as an Acrobat pdf download under the 'Pre 2000 Reports' heading on the DWI website.