Evaluation of matrix effect and chromatography efficiency: new parameters for validation of method development.

From the viewpoint of regulatory guidelines, validation of LC-UV and LC-MS based methods have the same requirements. Matrix effects are not considered for most method validations if they do not influence reproducibility or assay linearity. Since matrix effects can strongly suppress ionizaton efficiency and therefore reduce sensitivity, they must be evaluated (and discussed in the context of method development)--prior to method qualification. The severity of matrix effects is directly dependent upon chromatographic performance. We suggest that evaluation of matrix effects and LC efficiency is essential information for method assessment, optimization and transfer to other mass spectrometers, and should be a mandatory part of routine LC/MS method validation.