For example, a widely used tert-butyloxycarbonyl protecting group (Boc) is frequently cleaved during the ionization step. The presence of sodium or chloride ions can contribute to the formation of the molecular ion and hence its observed m/z ratio. On the other hand, the reaction can lead to the formation of isomeric product(s) having the same molecular mass, eventually resulting in incorrect data interpretation. All these factors contribute to the uncertainty of LC-MS analysis based solely on the mass spectroscopy data, thereby necessitating the application of additional methodology for this task, e.g., the RT assessment. Quantitative structure-retention relationships (QSRR) approaches are dedicated to the prediction of RT values based on the chemical structure, thereby improving the detection of the molecular peaks by LC-MS.