Retention time trajectory matching for target compound peak identification in chromatographic analysis

Retention time drift caused by fluctuations in physical factors such as temperature ramping rate and carrier gas flow rate is ubiquitous in chromatographic measurements. Proper peak identification and alignment across different chromatograms is critical prior to any subsequent analysis. This work introduces a peak identification method called retention time trajectory (RTT) matching, which uses chromatographic retention times as the only input and identifies peaks associated with any subset of a predefined set of target compounds. RTT matching is also capable of reporting interferents. An RTT is a 2-dimensional (2D) curve formed uniquely by the retention times of the chromatographic peaks. The RTTs obtained from the chromatogram of a test sample and of pre-characterized library are matched and statistically compared. The best matched pair implies identification. Unlike most existing peak alignment methods, no mathematical warping or transformations are involved. Based on the experimentally characterized RTT, an RTT hybridization method is developed to rapidly generate more RTTs without performing actual time-consuming chromatographic measurements. This enables successful identification even for chromatograms with serious retention time drift. Experimentally obtained gas chromatograms and publicly available fruit metabolomics liquid chromatograms are used to generate over two trillions of tests that validate the proposed method, demonstrating real-time peak/interferent identification.