Methods that deliver qualitative response are commonly applied – especially for fast screening purpose – in many analytical areas. Such methods are often based on immunoassays and used e.g. to detect allergens, GMOs, residues such as pesticides, contaminants such as mycotoxins, and ingredients in food and feed.
These methods are also called binary qualitative methods that produce one out of two possible responses i.e. yes or no.
Using a qualitative method and getting a positive result is important to have confidence that the compound analysed (analyte) is present at the concentration level of interest, e.g. a legal limit in the sample that was tested. Getting a negative result is essential to have confidence that the analyte is not present or at least at a concentration below a specified low level
To-date there was no internationally accepted guidance on the validation of qualitative testing methods in contrary to quantitative methods for which a harmonised IUPAC1/AOAC2/ISO3 protocol exists. Due to its role to provide quality assurance tools (e.g. validated methods, reference materials) for the implementation of European legislation, the JRC was well aware of the lack of a sound guidance protocol. Therefore, already in 2005, JRC scientists initiated a project to develop guidance for the validation of qualitative methods within IUPAC.
The IUPAC working group, chaired by Christoph von Holst of the JRC Institute for Reference Materials and Measurements (IRMM) began its work on the harmonised protocol in 2006, joining forces from some corresponding European projects and IUPAC. It was then submitted to the AOAC International in 2011, and has been recently included in a general guideline for method validation of qualitative binary methods.
"We are delighted that this important protocol has been now adopted internationally," stated Elke Anklam, Director of the JRC-IRMM. "This new guideline is based on our expertise in the field of method validation and will ensure that fast screening methods are fit-for-purpose."
The protocol was successfully tested on screening methods for the detection of meat and bone meal in animal feed, and of peanut protein in food products.
1 IUPAC: International Union for Pure and Applied Chemistry
2 AOAC: Association of Analytical Communities
3 ISO: International Standardisation Organisation
AOAC: Guidelines for Validation of Qualitative Binary Chemistry Methods (Chemistry Guidelines)