Validation of analytical procedures is imperative in demonstrating that a drug substance is suitable for a particular purpose. Common validation characteristics include: accuracy, precision (repeatability and intermediate precision), specificity, detection limit, quantitation limit, linearity, range, and robustness. In cases such as changes in synthesis of the drug substance, changes in composition of the finished product, and changes in the analytical procedure, revalidation is necessary to ensure quality control.
All analytical procedures should be validated. Identification tests are conducted to ensure the identity of an analyte in a sample through comparison of the sample to a reference standard through methods such as spectrum, chromatographic behavior, and chemical reactivity. Impurity testing can either be a quantitative test or a limit test. Both tests should accurately measure the purity of the sample. Quantitative tests of either the active moiety or other components of a sample can be conducted through assay procedures. Other analytical procedures such as dissolution testing or particle size determination may also need to be validated and are equally important.