DEVELOPMENT, PRODUCTION AND CERTIFICATION OF MICROBIOLOGICAL REFERENCE MATERIALS

Since 1986 the National Institute of Public Health and Environmental Protection (RIVM) in the Netherlands has been developing and testing reference materials (RMs) for use in the field of water and food microbiology within the framework of the 'Measurements and Testing Programme' (former BCR) of the European Union. The materials consist of gelatin capsules filled with artificially contaminated spray dried milk. Individual and collaborative studies on stability and homogeneity of the materials are described. The positive results obtained are followed by certification studies on certain reference materials. The results of two certification studies have now satisfactorily been completed, and certified values, related to the methods used, have been given for two certified reference materials (CRMs) containing the bacterial strains Salmonella typhimurium (5 cfp/capsule) and Ente-rococcus faecium (500 cfp, capsule), respectively. Two other RMs containing Bacillus cereus and Enterobacter cloacae will be certified by the end of 1994.