Kovats retention index

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') 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)} ') - log (t_{r (n)} ')}{log (t_{r (N)} ') - log (t_{r (n)} ')} 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' = the adjusted retention time.

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