Thermodynamic Definition of HPLC Dead Volume

The definition of dead volume in high-performance liquid chromatography and its determination on the basis of the thermodynamic Gibbs theory is discussed. The suggested thermodynamic approach can be applied to the description of any liquid chromatographic method such as normal phase, reversed phase, ion exchange, and even size exclusion. A method is suggested for the accurate calculation of the dead volume from mobile phase component disturbance peaks through the whole concentration range. The existence of negative values of capacity factors for some compounds is also explained.