Improved chlorhexidine carryover performance using the Alliance iS HPLC System

Carryover is an all-too-common problem for many users of High Performance Liquid Chromatography (HPLC) systems. There are multiple forms of carryover, including volumetric, or carryover as a result of void volumes in the flow path, and adsorptive carryover, where sample “sticks” or adsorbs to surfaces of the flow path. If a method suffers from carryover, it is important to know which form of carryover it is so that you can most effectively eliminate the source of the carryover. In many cases, methods may display both volumetric and adsorptive carryover. In this application note, Waters evaluates carryover of chlorhexidine on a variety of HPLC systems across various vendors. In addition, mitigation strategies, namely implementation of needle wash and/or extending washing are explored as well.