If the reference precursor ion mass with a mass tolerance of 0.010 Da was found in the MS1 feature list, then the corresponding MS2 signal masses were extracted. To do so, firstly, the MS2 spectra within the start and end time of the MS1 feature were centroided with the centroiding algorithm from the SAFD package, using a minimum intensity of 250 counts and a resolution of 20,000. 9,37 Secondly, the centroided MS2 spectra were used to obtain XICs for the present m/z values. The m/z values within a mass window of 0.020 Da (i.e., 0.010 mass tolerance) were grouped as a single XIC. Thirdly, the MS2 XICs went through two quality control criteria, which meant that the signal to noise ratio needed to be higher than 2 and at least 3 consecutive scans needed to have a higher intensity for both the forward and backward cumulative intensity means of XICs. For the MS2 XICs that passed the quality control, the Pearson's correlation coefficient was calculated with the MS1 XIC of the precursor ion, and the retention time (t r ) difference between the MS1 and MS2 XIC apex was obtained. Finally, the CNL model was applied by taking the median m/z of the MS2 XICs and calculating the CNL between the MS2 XICs and the precursor ion mass.