THE CERTIFICATION OF A REFERENCE MATERIAL FOR THE EVALUATION OF THE ISO METHOD FOR THE DETECTION OF SALMONELLA

A reference material (RM) containing Salmonella typhimurium was certif ied as CRM 507 by the Standards, Measurements and Testing Programme of the European Commission. The material consists of a gelatin capsule f illed with artificially contaminated milk powder. The material is cert ified for the evaluation of presence/absence methods based on the ISO 6579 procedure for the detection of Salmonella. In the certification s tudy 11 laboratories determined the presence/absence of Salmonella fro m each of 50 capsules. They also determined the mean number of colony- forming particles (cfp) and the homogeneity of the batch of RM accordi ng to an enumeration procedure. Certified values were calculated for b oth procedures separately. Based on the presence/absence procedure a f raction of capsules in which no Salmonella could be detected of 2.7% ( one-sided 95% confidence upper limit 4.4%) was as certified, for the e numeration procedure this fraction was 0.61% (one-sided 95% confidence upper limit 1.69%). The certified mean number of Salmonella cfp in on e capsule is 5.9 (two-sided 95% confidence interval 5.3-6.4). Data on the preparation, identification, stability (at-storage and higher temp eratures) and homogeneity of the material are presented.