Validation and Verification: the ISO 16140 scheme to choose the best method for your microbiological laboratory

Laboratory managers can choose between plate-based reference methods or proprietary methods. Faster but often more expensive, how can we be sure proprietary methods meet or exceed reference method performance?

IntroductionAnalytical methods and their performance parameters have been defined as one of the components of a microbiological criterion for food safety (Codex Alimentarius 2013). When making a decision based on an analytical result, one must ensure the robustness of the sampling approach, how the sample was taken, and, lastly, how it was analysed. To achieve either short time-to-result or high throughput, food business operators often consider using alternative (and sometimes proprietary) methods. For compliance, they must have the same efficacy (specificity, sensitivity, reproducibility) as the reference method, as defined by the various sections of ISO 16140. This standard has been in place in Europe since 2005. Article 5 of Commission Regulation (EC) No 2073/2005 states that “The use of alternative analytical methods is acceptable when the methods are validated against the reference method in Annex I and if a proprietary method, certified by a third party in accordance with the protocol set out in EN/ ISO standard 16140 or other internationally accepted similar protocols, is used.”
The new ISO 16140 Scheme: from one standard to six parts (for now)ISO 16140:2003 underwent a lengthy revision that split the regulation into six parts:Part 1: Vocabulary (published June 2016)Part 2: Protocol for the validation of alternative (proprietary) methods against a reference method (published June 2016)Part 3: Protocol for the verification of reference methods and validated alternative methods in a single laboratory (published January 2021)Part 4: Protocol for method validation in a single laboratory (published July 2020)Part 5: Protocol for factorial interlaboratory validation for non-proprietary methods (published July 2020)Part 6: Protocol for the validation of alternative (proprietary) methods for microbiological confirmation and typing procedures (published November 2019)The former standard took into consideration all aspects of development, implementation, and monitoring of an alternative method. In order to facilitate the process, the split aims to specify the roles and responsibilities of the analytical solution provider and the end-user (i.e. analytical laboratory). In the present article, the focus is on parts 2 and 3. The verification process was omitted in the previous version of ISO 16140, leading to endless discussion at the laboratory level regarding accreditation and customer acceptance that alternative methods were being properly implemented.
Validation vs. verificationFor those involved in method development, there is always a discussion about the proper use of the terms validation and verification. - The purpose of validation is to demonstrate the equivalence of an alternative method to the reference method for the matrices validated, based on defined method criteria.- The purpose of verification is to demonstrate that in the hands of the user the method can be performed to meet the defined method criteria.In short, validation is the responsibility of the manufacturer and verification is the responsibility of the laboratory. Validation is done once, under the scheme of ISO 16140 Part 2, by a recognized validation body (AFNOR, MICROVAL, AOAC, NORDVAL, etc.) and regularly updated. Verification is done by