The AutoChrom (ACD/Labs, Toronto, ON, Canada) software tool set and the ACD/ChromGenius (Version 2021.1.1) package was used for the modeling of retention times of cyclic peptides analyzed using the standard 8 min method. Using the methods described in our previous work, QSRR models were built for each test analyte by using 80 training analytes with the greatest Tanimoto similarity index to the test molecule. No weightings were assigned to molecular descriptors when developing QSRR models with ACD/ChromGenius. For additional details, refer to the methods reported for this approach from our prior studies .