Analytical method transfer using equivalence tests with reasonable acceptance criteria and appropriate effort: extension of the ISPE concept.

A method development process is commonly finalized by a method transfer from the developing to the routine laboratory. Statistical tests are performed in order to survey if a transfer succeeded or failed. However, using the classic two-sample t-test can lead to misjudgments and unsatisfying transfer results due to its test characteristics. Therefore the International Society of Pharmaceutical Engineering (ISPE) employed a fixed method transfer design using equivalence tests in their Guide for Technology Transfer. Although it was well received by analytical laboratories worldwide this fixed design can easily bring about high beta-errors (rejection of successful transfers) or high workload (many analysts employed during transfer) if sigma(AN) (error due to different analysts) exceeds 0.6%. Hence this work introduces an extended concept which will help to circumvent this disadvantage by providing guidance to select a personalized and more appropriate experimental design. First of all it demonstrates that former t-test related acceptance criteria can be scaled by a factor of 1.15, which allows for a broader tolerance without a loss of decision certainty. Furthermore a decision guidance to choose the proper number of analysts or series at given percentage acceptance limits (%AL) is presented. Copyright 2010 Elsevier B.V. All rights reserved.