ChromGenius: Molecules with No Estimated tR Values

Description

When running Estimate Prediction Accuracy in ChromGenius, some molecules may appear in gray, with no estimated retention time (tR) values. This indicates that the software was unable to generate a reliable correlation equation for those structures under the current option/parameter settings.

As a result:

• tR prediction is not calculated (tR Calc remains blank).
• Overall estimation accuracy for the dataset may be suboptimal.

Solution

1. Identify affected molecules:
   • In the estimation results, note molecules displayed in gray with no predicted tR.
2. Test one such molecule:
   • Double-click the structure to open it in ChemSketch.
   • Attempt to obtain Results for that structure.
   • Confirm that the tR Calc column is blank, indicating prediction failure.
3. Adjust parameter settings:
   • Reopen ChromGenius options for the estimation/prediction model.
   • Start with a limited set of parameters to simplify the model.
4. Gradually expand parameters:
   • Increase the number of allowed parameters stepwise (for example, add additional descriptors one by one).
   • After each adjustment, rerun Estimate Prediction Accuracy and check:
     • Whether more adequate correlation equations are found.
     • Whether previously gray molecules now receive predicted tR values.
     • Pay attention to Residual (should be close to 1) and Standard Deviation (close to 0) after each adjustment.
5. Review the new results.
6. Bring more structures to the database that are similar to the ones with failed calculated tR value.