Robustness in qualitative analysis: a practical approach

The growing importance of qualitative information as output in analytical laboratories in response to client’s demands is unquestionable. The number of reliable, validated, qualitative methods available for implementation in routine laboratories is therefore increasing in the same way. Unfortunately, metrological support for this type of measurement process is not yet available.In this article, we present a practical approach to assessing the robustness of a qualitative method. The procedure proposed is based on selecting the critical variables and estimating reliability and false positive and false negative rates. The qualitative procedure selected is automated and was developed for monitoring the degree of exhaustion of alkaline degreasing baths based on the total contents of oil/grease and surfactant. The study was carried out at two concentration levels for each family of compounds.