2013 ISPAM Mid-Year Mtg Book

Therefore verification is divided into two steps: - Demonstration of the competence of the laboratory to perform the method in accordance with the parameters established during the validation for a defined matrix. Use of at least? one relevant matrix is required. - Verification of the method on other matrices. The types of matrices to be tested depend on the diversity of the matrices tested routinely by the laboratory. The selected matrices shall be representative of the types tested by the laboratory and shall also be relevant to the target microorganisms of the method. However, for laboratories testing a broad range of products (foods, feeds, environmental and primary production stage samples) this approach is not practicable. In such cases, the laboratory shall verify a selection of relevant matrices with different properties. The number of matrices to be tested must be defined. 7 Protocol for verification of qualitative methods 7.1 General The relevant performance characteristic for verification of a qualitative microbiological method is the level of detection. The level of detection is “the lowest concentration of microorganisms that may be determined with a given probability under the experimental conditions of the method under evaluation” (see ISO 16140-1). The theoretical level of detection for microbiological methods is 1 CFU per test portion. However, in practice, the level of detection may be affected by the sample matrix. For example, in the presence of high numbers of competitive flora it is not always possible to detect a single and often sub-lethally damaged cell. For microbiological methods the level of detection is expressed as LOD 50. NOTE For current ISO standard qualitative methods there is no validation data for LOD 50. For alternative (proprietary) methods, evaluation of the level of detection shall be performed by calculating the relative level of detection (RLOD) which is defined as the ratio of the LOD 50 of the alternative method and the reference method. Use of RLOD will be discussed with WG2. 7.2 Determination of LOD 50 In this study, the laboratory shall is encouraged use Certified Reference Material (CRM) with a concentration of 1-5 CFU per test portion. The number of samples for each matrix is 10 with a recommended acceptance criterion of 100 %. When no CRM is available, the laboratory should produce low level inocula as described in Annex A ( to develop ). 8 Protocol for verification of quantitative methods

Comment [M1]: Paul will provide altrenate language or clarification.

8.1 General