Beyond pass/fail: a procedure for evaluating the effect of carryover in bioanalytical LC/MS/MS methods

Eliminating carryover from bioanalytical methods can be a time and resource consuming process. While it is necessary to investigate root causes of the carryover and reduce problem areas, complete elimination of carryover may not be practical or even possible. The purpose of this paper is to suggest an avenue to investigate the effect of carryover within an analytical run rather than employ a simple pass/fail criterion. With more robust carryover information a risk threshold level can be established for individual injections based on the peak response of the previous injection. It is then possible to quickly evaluate the risk that any value in an analytical run has been adversely affected by a previous injection. Those samples which are identified as "at risk" can be reanalyzed to obtain a value that is not affected.