Prediction of Retention Time and Collision Cross Section (CCSH plus , CCSH-, and CCSNa plus ) of Emerging Contaminants Using Multiple Adaptive Regression Splines

Ultra-high performance liquid chromatography coupled to ion mobility separation and high-resolution mass spectrometry instruments have proven very valuable for screening of emerging contaminants in the aquatic environment. However, when applying suspect or nontarget approaches (i.e., when no reference standards are available), there is no information on retention time (RT) and collision cross-section (CCS) values to facilitate identification. In silico prediction tools of RT and CCS can therefore be of great utility to decrease the number of candidates to investigate. In this work, Multiple Adaptive Regression Splines (MARS) were evaluated for the prediction of both RT and CCS. MARS prediction models were developed and validated using a database of 477 protonated molecules, 169 deprotonated molecules, and 249 sodium adducts. Multivariate and univariate models were evaluated showing a better fit for univariate models to the experimental data. The RT model (R2 = 0.855) showed a deviation between predicted and experimental data of +/- 2.32 min (95% confidence intervals). The deviation observed for CCS data of protonated molecules using the CCSH model (R2 = 0.966) was +/- 4.05% with 95% confidence intervals. The CCSH model was also tested for the prediction of deprotonated molecules, resulting in deviations below +/- 5.86% for the 95% of the cases. Finally, a third model was developed for sodium adducts (CCSNa, R2 = 0.954) with deviation below +/- 5.25% for 95% of the cases. The developed models have been incorporated in an open-access and user-friendly online platform which represents a great advantage for third-party research laboratories for predicting both RT and CCS data.

Automated summary

Ultra-high performance liquid chromatography coupled to ion mobility separation and high-resolution mass spectrometry instruments are valuable for screening emerging contaminants in the aquatic environment. However, in the absence of reference standards, the prediction of retention time (RT) and collision cross-section (CCS) values is important. This study developed Multiple Adaptive Regression Splines (MARS) prediction models for RT and CCS, which were validated using a database of protonated molecules, deprotonated molecules, and sodium adducts. The developed models, integrated in an open-access online platform, enable the prediction of both RT and CCS data.