Gregory K. Webster

The use of ultrahigh-pressure liquid chromatography (UHPLC) is now commonplace among pharmaceutical laboratories. However, until depreciation cycles replace traditional high performance liquid chromatography (HPLC) systems that operate at a maximum pressure of 400 bar, the advantages of UHPLC cannot be realized worldwide. Thus, product methods developed using UHPLC capabilities cannot directly transfer these methods to receiving laboratories without qualified UHPLC availability.

Because not all laboratories have UHPLC systems, reverse scaling of methods from UHPLC to HPLC is often needed, particularly in the pharmaceutical industry. The use of superficially porous particles can facilitate this process.

This article reviews several common applications of the critical-pair approach to column chromatography as it is applied under pharmaceutical guidelines and validation strategies.