Question

Which of the following equations give the expression for plate number, N when ‘tR’ is the adjusted retention time and ‘Wb’ is the width at the base of the peak which is equal to 4 standard deviations.

(a) 16 tR^2/Wb

(b) 4 tR^2/Wb

(c) (4tR/Wb)^2

(d) 4 (tR/Wb)^2

I had been asked this question at a job interview.

My question is taken from Column Efficiency and Column Resolution topic in section Chromatography of Analytical Instrumentation

Answer 1

The correct answer is (c) (4tR/Wb)^2

The best I can explain: The expression for plate number, N is given as N = (4tR/Wb)^2. It is a dimensionless quantity.