Hello. If you want to compare the efficiency you must measure the peak width of your interest peak (in the best case you must run a standard like acenaphthene) and with the retention time you can calculate the number of theorical plates and therefore the efficiency.

N: 5.545(Tr / W)2  tr: retention time, W: peak width (in units of time), N: Number of Theorical Plates

Another way is know H where H is Height equivalence and its formula is:

H: L / N where L is the lenght of column in mm and N thre previous calculated number of plates.

With this values you can compare the effciency between columns.

Thank you all.

The conventional approach to compare the chromatographic performance of columns is to plot normalized efficiency (HETP - height equivalent to a theoretical plate) as a function of mobile phase flow rate or linear velocity, often referred to as a van Deemter plot.