Kovats retention index

Kovats retention index or simply Kovats index or retention index is a method of quantifying the relative elution times of compounds in gas chromatography in such a way as to help positively identify the components of a mixture.cite journal | last = Kovats | first = E. | year = 1958 | title = Characterization of organic compounds by gas chromatography. Part 1. Retention. indices of aliphatic halides, alcohols, aldehydes and ketones.| year = 1915 | volume = 41 | pages = 1915 | journal = Helv. Chim. Acta] [GoldBookRef |title = retention index, I in column chromatography |file = R05360]

Expression

The method takes advantage of the linear relationship between the values of $log\; (t\_r\text{'})$ and the number of carbon atoms in a molecule. The value of Kovats index is usually represented by "I" in mathematical expressions. Its applicability is restricted to organic compounds. The Kovats index is given by the equation

$I\; =\; 100\; imes\; left\; [\; n\; +\; (\; N\; -\; n\; )\; frac\{log\; (t\_\{r\; (unknown)\}\; \text{'})\; -\; log\; (t\_\{r\; (n)\}\; \text{'})\}\{log\; (t\_\{r\; (N)\}\; \text{'})\; -\; log\; (t\_\{r\; (n)\}\; \text{'})\}\; ight\; ]$

Where;

$I\; =$ Kovats retention index,
$n\; =$ the number of carbon atoms in the smaller alkane,
$N\; =$ the number of carbon atoms in the larger alkane,
$t\_r\text{'}\; =$ the adjusted retention time.

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