Retention indexes and stationary phase constants

These parameters have been developed to pursue at least three objectives  

The retention index related to a given stationary phase is determined as follows. When a mixture containing compounds belonging to a homologous series of 

On a graphical representation, the carbon number n versus log usually yields a series of well lined up points according to the following semi-empirical mathematical relationship  

The adjusted retention time corresponds to the retention time of an alkane having n atoms of carbon, minus the dead time d b are numerical coefficients. The slope of the graph obtained depends on the overall performance of the column and the operating conditions of the chromatograph. 

A compound (X) is now injected onto the column without changing the tuning of the instrument. The resulting chromatogram will enable 4, the Kovats retention index, to be calculated for X and the specific column employed this is equal to 100 times the equivalent number of carbon atoms of the theoretical alkane having the same adjusted retention time than X. Two methods can be used to find 

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