A known compound and at least one adduct, modified form, or peptide of the known compound are separated from a sample mixture and analyzed. An XIC is calculated for each of M product ions of the known compound and L product ions of the at least one adduct, modified form, or peptide. A first XIC peak group is calculated from the M XICs and a second XIC peak group is calculated from the L XICs using curve subtraction. Representative first and second XIC peaks are selected for the two XIC peak groups. The retention time of the second XIC peak is shifted by an expected retention time difference found from a database. The retention time of the first XIC peak is verified as the retention time of the known compound if the difference of the retention times of the first and second XIC peaks is within a threshold.