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Method Validation
Is Full Method Validation Compulsory Before Testing Active Concentration?
“Do I need to perform full method validation on my product before running the chemistry test to determine the concentration of actives?”
This is one of the most common questions we get from manufacturers. Before answering, let’s understand why method validation matters in the first place.
Why Method Validation Is Needed
Every disinfectant, antiseptic, or cosmetic product is a unique formulation — not just the active ingredient, but also surfactants, stabilizers, pH adjusters, fragrances, and other excipients. Any of these components can interfere with the analysis of the others.
When a laboratory first develops an analytical method, chemists typically work with the pure active substance in isolation. When that same method is later applied to a finished, formulated product, the other ingredients in the matrix can interfere with the signal — meaning the reading for active concentration may no longer be accurate.
Method validation is the scientific process of demonstrating that an analytical method is fit for its intended purpose — in this case, fit for your specific formulation.
What We Look at During Method Validation
- Selectivity – Can the method distinguish the target analyte from everything else in the sample?
- Linearity & Range – Does the analytical response increase proportionally with concentration across the intended working range, even in the presence of other formulation components?
- Accuracy – How close are the results to the true value?
- Precision – Does the method produce consistent results under the same conditions, and across different conditions/laboratories?
- Limit of Detection (LOD) – What is the smallest amount of analyte the method can reliably detect?
- Limit of Quantification (LOQ) – What is the lowest concentration that can be measured accurately and reliably?
- Robustness – Does the method continue to perform reliably despite small, deliberate variations in routine laboratory conditions?
Based on the outcome of validation, the method is fine-tuned to give the most accurate result for that specific product. A full method validation is not a quick, single-step process. It typically requires testing multiple prototype conditions and combinations before the method is confirmed as fit for purpose.
Short answer: in most regulated contexts, yes.
ECHA’s official guidance on this requirement (Guidance on the Biocidal Products Regulation, Volume I: Identity of the active substance/physico-chemical properties/analytical methodology, Parts A+B+C, Version 2.1, March 2022) explains what “suitable” means in practice: the analytical method must accurately determine the active substance content in the formulated product, and where a product contains more than one active substance, the method must be able to determine each active in the presence of the others. This is the regulatory basis for the selectivity/interference issue described above.
In practice, this means manufacturers need a one-time method validation to prove the method is reliable for their formulation. Once validated, that method is then used consistently for:
- Stability testing, and
- Routine testing of production batches.
When Is Full Method Validation Not Required?
Full method validation may be skipped only when both of the following apply:
- The product has a simple formulation, and the other components are not expected to interfere with the result, and
- The test report will not be used for regulatory registration — only for in-house or R&D purposes.
Even in this case, we still recommend a simple calibration check against your specific product to confirm the result is accurate — it’s a small step that protects you from misleading data.
How TECOLAB Can Help
At TECOLAB, we help you develop analytical methods tailored to your specific product formulation and perform comprehensive method validation where required. This ensures you have reliable, defensible data to support both internal R&D and regulatory submissions.
Whether you’re developing a new analytical method or validating an existing one, our experts are here to support your project.