A plurality of measured product ion spectra is produced using a DIA tandem mass spectrometry method. One or more product ions are retrieved from a spectral library of known compounds or one or more theoretical product ions are calculated for the known compounds of a database. For each known or theoretical product ion, an XIC is calculated from the measured product ion spectra. Measured XIC peaks above a threshold intensity are grouped for the known compounds producing a subset of known compounds. Known or theoretical retention times are retrieved or calculated for the subset of known compounds. A regression function is calculated to correct the known or theoretical retention times using the known or theoretical retention times of the subset of known compounds as the independent variables and the measured retention times of the measured XIC peak groups of the subset of known compounds as the dependent variables.