Development and Application of Liquid Chromatographic Retention Time Indices in HRMS-Based Suspect and Nontarget Screening

There is an increasing need for comparable and harmonized retention times (tR) in liquid chromatography (LC) among different laboratories, to provide supplementary evidence the identity of compounds high-resolution mass spectrometry (HRMS)-based suspect nontarget screening investigations. In this study, a rigorously tested, flexible, less system-dependent unified time index (RTI) approach LC presented, based on calibration elution pattern. Two sets 18 calibrants were selected each ESI+ ESI-based maximum overlap with chemical similarity indices from total set 2123 compounds. The resulting set, RTI range between 1 1000, was proposed as most appropriate system after rigorous evaluation, coordinated by NORMAN network. validation done externally instrumentation conditions. can also be used check reproducibility quality quantitative structure–retention relationship (QSRR)-based models built developed systems, which assist removal false-positive annotations. applicability domains QSRR allowed completing identification process higher confidence substances within domain, while indicating those results should treated caution. improve increase comparability laboratories demonstrated two examples. All RTI-related calculations performed online at http://rti.chem.uoa.gr/.