DEVELOPMENT, PRODUCTION AND CERTIFICATION OF MICROBIOLOGICAL REFERENCE MATERIALS

Since 1986 the National Institute of Public Health and Environmental P rotection (RIVM) in the Netherlands has been developing and testing re ference materials (RMs) for use in the field of water and food microbi ology 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. Indiv idual and collaborative studies on stability and homogeneity of the ma terials are described. The positive results obtained are followed by c ertification studies on certain reference materials. The results of tw o certification studies have now satisfactorily been completed, and ce rtified values, related to the methods used, have been given for two c ertified reference materials (CRMs) containing the bacterial strains S almonella typhimurium (5 cfp/capsule) and Ente-rococcus faecium (500 c fp, capsule), respectively. Two other RMs containing Bacillus cereus a nd Enterobacter cloacae will be certified by the end of 1994.