Case Study: Requirements for analytical method development and validation
Analytical methods in the food system are used to determine if there is a contaminant present in the feed or food stuff. It is important to ensure analysis methods are validated as fit for purpose.
A number of analytical methods are validated in the European Commission decision 2002/657. The validation allows the user to determine and demonstrate the methods performance and to challenge the method. This allows the user to verify the result for legal implications and assure the correct results are retrieved from a particular method.
The key validation parameters or performance characteristics of a method are outlined in the following table:
|Accuracy||Closeness of agreement between the average value obtained from a large series of test results and an accepted reference value|
|Precision||Expresses the closeness of agreement between a series of measurements obtained from multiple sampling of the same homogenous sample|
|Specificity||The ability to assess indisputably the target analyte in the presence of components which may be expected to be present (such as impurities)|
|Limit of Detection (LOD)||The lowest amount of analyte in the sample which can be detected but not necessarily quantified as an exact value|
|Limit of Quantification||The lowest amount of analyte in the sample which can be quantitatively determined with suitable precision and accuracy|
|Linearity||The ability (within a given range) to obtain test results which are directly proportional to the concentration (amount) of the analyte in the sample|
|Range||The interval between the upper and lower concentration (amounts) of analyte in the sample for which it has been demonstrated that the analytical procedure has a suitable level of precision, accuracy and linearity|
|Robustness||Shows the reliability of an analysis with respect to deliberate variations in method parameters|
|Stability||The degree to which the substance is subject to degradation in time|
Purpose of Validation
If we get a positive result: To be able to conclude with confidence that the target analyte is present in the sample at or above the legal limit
If we get a negative result: To be able to conclude with confidence that if the analyte is present at all then it must be below the legal limit or undetectable at ‘as low as reasonable achievable’ (ALARA).
What we would like you to do
Please answer the following questions in the comments section below:
Have you any experience in a laboratory or testing analytical methods for any of these performance characteristics?
Do you think method validation against these performance characteristics are important or necessary?