An analysis of the SFSTP guide on validation of chromatographic bioanalytical methods: progress and limitations

The Société Française des Sciences et Techniques Pharmaceutiques (SFSTP) published in 1997 a guide on the validation of chromatographic bio-analytical methods, which introduces new concepts in three different areas: stages of the validation, test of acceptability of a method and design of experiments to perform. In 'stages of validation', the SFSTP guide requires two phases to validate a method. The first phase, called 'prevalidation', is intended to (1) identify the model to use for the calibration curve; (2) evaluate the limits of quantitation; and (3) provide good estimates of the precision and bias of the method before designing the 'validation' phase per se. In the 'test of acceptability', the use of the interval hypotheses is envisaged by the SFSTP guide, not on the parameters of bias and precision, but on individual results by mixing mean bias and intermediate precision in a single test. The SFSTP guide also avoids the use of Satterthwaite's df for testing the acceptability. The reasons for those choices are discussed extensively. In 'design of experiments', much effort has been devoted to improving the quality of results by optimally designing and sizing the experiments to perform in validation. The rationale for using near D-optimal designs for the calibration curve is demonstrated and sample sizes are proposed to correctly size the validation experiments.