Page 224 - Applied Pharmacognosy

Retention index (Kovat’s index , I)

linear relationship between log tRof member of
homologus series of hydrocarbons and the number of C
atoms
Kovat’s index of analyte is calculated based on its tR and tR

of two n- alkanes (hydrocarbons)which elute in front and
behind it ( all run on the same column )

I = 100 x { n+(N-n) } log tR unknown – log tR(n) / log tR(N) –
log tR(n)

n is number of carbon atoms in the smaller alkane

N is number of carbon atoms in the larger alkane
I is Kovat’s index

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