Prediction of liquid chromatographic retention time using quantitative structure-retention relationships to assist non-targeted identification of unknown metabolites of phthalates in human urine with high-resolution mass spectrometry

•A prediction model for accurately predicting retention time of a given structure.•The model increases the identification reliability in non-targeted analysis.•Three structural specific ions can prioritize candidates from high-resolution MS data.•Two unknown metabolites were identified with the aid of the developed model.•A structure-ion intensity relationship model was used to estimate levels of unknowns.