What is a Kováts retention index in gas chromatography, and how do I calculate it?
The Kováts retention index (or Kováts index) of a compound is its retention time normalized to the retention times of adjacently eluting n-alkanes.
It depends on the fact that
For an isothermal chrtomatogram, you use the following equation to calculate the Kováts index,
First, you run a chromatogram of a standard alkane mixture in the range of interest, say from
You might get something like the chromatogram below.
Then you do a co-injection of your sample with the standard alkanes.
Assume that the retention times were: sample = 3.12 min;
Even many years later and in a different laboratory, you can reproduce this retention index even though your old retention times no longer have any meaning..