By Kenneth D. Berthelette, Jennifer M. Nguyen, Jonathan E. Turner
Strategic method development processes can significantly improve the speed and efficiency of method development activities. The most common approaches to method development can be broken into four categories: One Factor at a Time (OFAT), Full Factorial Screening (FFS), Tiered Screening (TS), and Analytical Quality by Design (AQbD). Each have their own strengths and weaknesses including the need for experienced analysts, or access to different types of software.
The TS approach balances the speed of OFAT with the comprehensive testing of FFS.6 In a tiered screen, method development activities are performed step-wise, with a decision step after each experimental screen. One variable is tested at a time, which is then “locked” in for subsequent testing of additional variables.
To demonstrate the use of a tiered screening approach, a mixture of ten antibiotic compounds including amoxicillin, clavulanic acid, piperacillin, tazobactam, ampicillin, oxacillin, cloxacillin, dicloxacillin, azithromycin, and cefalexin was created. Continue reading to learn how Waters leveraged a generic systematic protocol to separate a variety of APIs in a single run.