A generalization of the retention index system including linear temperature programmed gas—liquid partition chromatography

The different ways of describing peak positions on gas chromatograms are reviewed. The retention index is preferred to the theoretical nonane system and the relative retention. The equation given by Kováts for the calculation of the retention index in case of isothermal operation is transformed to a more general form to include also the case of linear temperature programmed operation. This generalized equation gives the same retention index for both ways of operation.