AOAC GFA Stakeholder Program Meeting Book (March 15, 2023)

3.2 Biological Replicate One sample is extracted with a given number of replicates. Example for three biological replicates: Three separate test portions should be weighed, and each test portion should be tested following the testing method as specified by the method developer. 3.28 Technical Replicate One extracted sample is analyzed more than one time. Example for two technical replicates: A sample is extracted once and the resulting extract is tested on two separate lateral flow devices. “Biological Replicates” – These 2 terms here, “Biological” vs “Technical” replicates are confusing, non-specific and apt to cause confusion and misunderstanding. You can use other, more specific terms to describe the procedures. This definition is inadequate. If you must use, I would suggest that the first sentence here is not a definition really. It should be: “Replication whereby multiple test portions are extracted and analyzed separately as individual, independent trials.” Rationale: AOAC should be using terms that utilize the recent advances in statistical sampling theory. The best resource for terms are the AAFCO Good Samples and Good Test Portions guidance documents. The terms “biological replicate” and “technical replicate” and the associated concepts are not used in the contemporary literature. “Technical Replicate” – In a qualitative LFD method, there are any number of unspecified places where a replicate split could be performed post-extraction. For example, in many LFD methods there is a step where the operator dilutes an extract in buffer. Do you do this replication split step before or after the addition of buffer? This lack of specificity may lead to confusion and problems in the future. I prefer this term not be used in the document and be replaced by more specific instructions where used. Notes TheAAFCO document doesn’t address this level of replicate analysis in their definitions – these terms address the re-use (or not) of a test portion extract. Document will be reviewed to ensure all use of the word “sample” are used with the appropriate modifier.