Certified reference material for the quality control of cadmium, copper, nickel and zinc determination in estuarine water (CRM 505)

Analyses of estuarine water samples are routinely carried out by a number of laboratories to monitor the level of environmental contamination by toxic substances, e.g. heavy metals. A series of interlaboratory studies has been organised by the Community Bureau of Reference, BCR (now renamed Standards, Measurements and Testing Programme) to improve the quality of the determinations of selected trace metals in estuarine water samples. The improvement achieved allowed to produce a reference material (CRM 505) which was certified for its content of Cd, Cu, Ni and Zn. Further improvements were considered to be necessary for the certification of other trace elements, e.g. Pb. This material was collected in the Tagus Estuary, carefully prepared (filtered and acidified) and its homogeneity and long term stability were verified. This paper presents the work performed for the certification of Cd, Cu, Ni and Zn. Indicative values are reported for As, Co, Fe, Mn, Pb and V.