Topics - Retention Time

Retention Time Theretention time of a solute is taken as the elapsed time between the time of injection of a solute and the time of elution of the peak maximum of that solute. It is a unique characteristic of the solute and can be used for identification purposes. The corrected retention time of a solute is the retention time minus the retention time of a completely unretained solute. For gas chromatography an air peak of often used as a non-retained peak. For liquid chromatography (HPLC) many substances have been used including salts, deuturated solvents, uracil (reversed phase) and benzene (normal phase), read the Dead Volume topic for more information. By multiplying the corrected retention time of a solute by the exit flow rate then the corrected retention volume can be obtained. If the mobile phase is compressible (i.e. the mobile phase is a gas) a pressure correction must be applied which is a function of the column inlet-outlet pressure ratio. Values of the corrected retention volume per ml of stationary phase for a solute measured over a range of temperatures can provide the standard energy of distribution, the standard enthalpy of distribution and the standard entropy of distribution for the solute concerned.