2013 ISPAM Mid-Year Mtg Book
For validated qualitative methods, the relevant performance characteristic for verification is: - Level of detection (LOD). For validated quantitative methods (colony count or MPN), the relevant performance characteristics for verification are: -Intralaboratory reproducibility (intermediate precision). -Measurement uncertainty (U). -Repeatability (s r ). -Trueness (bias; if the reference method is available). 5 Verification The objective of method verification is to assess the performance of a method in the user laboratory against the specifications of the method established during the primary validation and to assess the method performance on non-validated matrices. It is not necessary to determine all performance characteristics again, only those that are dependent on the user laboratory, for example sample types, operators, equipment, media, etc. The laboratory shall demonstrate that it is capable of performing the method. The laboratory shall demonstrate that the method performs satisfactorily on the matrices tested. Table 1 summarizes the relevant performance characteristics of microbiological methods for validation and verification.
Performance Characteristic Trueness (bias) Levelof Detection
Qualitative Methods
Quantitative Methods
Validation
Verification
Validation
Verification
+
+
+
+
Limit of Quantification Repeatability
+ (if relevant)
+
+
+ (intralaboratory reproducibility)
Reproducibility
+
Inclusivity Exclusivity
+ +
+ +
Measurement uncertainty
+
+
+
+
6 Selection of sample types and number of samples and replicates tested The choice of matrices depends on the sample types routinely tested in the laboratory. A laboratory shall demonstrate that the selected method is suitable for all their sample types, including any sample types not included in the validation study.
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