Question

Calculate the Kovats retention index for an unknown using the retention times 1.5 min for CH,, 12.7 min for octane, 14.3 min for the unknown, and 18.7 min for nonane. T =

Answer 1

An50୧୪ Given that, retention time = 1.5min. for Chu Octane -12.7 min unknown -14.3 min nonane = 18.7 min Hede, To calculate the kovat s setention index from setention times of Known linead al kanes using the following formula: I=100/n+(x-7) log(tylunknown)-109 (t:'(n)) 7 105(5%Cw).log(ti'(n)) where, n is the number of carbon atoms in the lower linear alkaneCoctane) Nis the number of caš bon atoms in the higher lineax alkane (nonane). Hence, n=8&N=9. ty' is the adjusted setention time to solute ty'=to-tm The setention time for lower linead al kanceCoctane), to' (n) = 12.7-405 to (n) = 112 min 'the detention time for higher linear alkane (nonane) ts'(N) = 1809-105. to'l) = 1712 min

The retention time for unknown, to' (unknown) = 1403-105 ty (unknown) ="1208 miss substitute the values in 0 .we get, 1 log 12.8-109 11:2 log 1702 - 109 1102 I=100/ I +100[33|1265] I= 831.12. Therefore, the Kovats setention index for the unknown is /83/•/27 so