According to classical chromatographic methods, RT can be calculated using the chromatographic process equation: 𝑅 𝑇 = 𝑡 𝑑 ( (𝑉 𝑚 + 𝐾 𝑝 𝑉 𝑠 ), where td is the dead time, Kp is the partition coefficient between stationary and mobile phases, Vs and Vm are volumes of stationary and mobile phases, and f refers to the flow rate. This approach requires availability of the Kp values which have to be either found in literature or measured experimentally. However, using the literature data with vastly varied experimental conditions introduces additional errors to the calculations. Xu and co-authors estimated this error as 1.34 mL / flow rate. For example, for our standard LC-MS spectrum with the flow rate of 3 mL/min and duration of 120 s, or 2 min, the expected RT error should be 1.34/3 = 0.45 min, or 27 s. Nevertheless, this approach pertains to the transition of RT from one condition to another, a consideration that is not applicable to large libraries with mostly new compounds like Enamine stock or Enamine REAL Database.