Topics - Specific Retention Volume
Specific Retention Volume
The specific retention volume of a solute is the corrected retention volume of the solute per unit mass of stationary phase. The corrected retention volume is obtained from a column carrying a known weight of stationary phase and is measured at a carefully controlled, accurately known temperature. The corrected retention volume is taken as the difference between the solute retention volume and the dead volume. The retention volume is taken as the volume of mobile phase that passes through the column from the time of injection to the elution time of the peak maximum. The dead volume is taken as the volume of mobile phase that passes through the column from the time of injection to the elution time of the peak maximum of a completely untretained solute. If the mobile phase is a liquid, no pressure correction is usually necessary, if the mobile phase is a gas, then all measured volumes must be corrected for the compressibility of the gas. If the specific retention volume is divided by the density of the stationary phase, the corrected retention per ml of stationary phase can be calculated, the logarithm of which gives the standard energy of distribution. If the standard energy of distribution is determined over a range of temperatures, then, by plotting the corrected retention volume per ml of stationary phase against the reciprocal of the temperature, the standard enthalpy and standard entropy of the distribution can be calculated.