A qualifier ion (a less abundant ion of a target compound that is typically always present in a known ratio to the target), is most often used when utilizing GC/MS (gas chromatography / mass spectrometry) to identify and quantify target compounds.
The concentration of an analyte is quantified by a ‘target ion’ but the ‘qualifying ion(s)’ are used for positive identification of our target. Most compounds when analysed by GC/MS will have a unique ratio of target ion to qualifier ions.
If something in the sample matrix interferes with one of these qualifying ions, causing this ratio to be outside of our criteria, it means that the concentration we report may or may not be all due to our target analyte, resulting in the potential high bias.
Thus the comment "Qualifying ion outside of acceptance criteria. Results are tentatively identified and potentially biased high" is added. We may also add the comment to indicate that there’s at least X.XX mg/kg of the target analyte, but due to something in the sample matrix, the result could be biased high.
Because the source of the interference is from within the sample matrix, there is little remedy to avoid or eliminate the effect on the sample results.