Failing specificity due to a gradient artifact

[estelarascon]

Hi,
We are testing the specificity of an old reverse phase method (gradient), we have found out that there is a gradient artifact showing right at the retention time of our peak of interest. We have considerably modified the gradient to move the system peak away from the compound of interst, to conlcusively determined that it is indeed a system's peak. Can anybody comment on how to approach specificitiy in a situation like this? This is my first time handling a specificity validation.
Kind Regards,
AR

[tom jupille]

If there is an artifact peak exactly at the retention time of the analyte, then the original method is, in fact, not specific for that analyte. Your modified method *is* specific for the analyte (obviously assuming you have checked the retention of other potential interferences).