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. The van Deemter equation describes plate height in terms of constants A, B, C,

ID: 588657 • Letter: #

Question

. The van Deemter equation describes plate height in terms of constants A, B, C, and the linear velocity, u. Which statement is NOT true for the van Deemter equation? lu A takes into account multiple pathways through the column. The value of A is column specific and independent of linear flow. a) b) Btakes into account longitudinal diffusion of the analyte in the mobile phase. The value of B c) Ctakes into account equilibrium time between the stationary and mobile phase. The value d) To minimize plate height, the optimal flow rate is the minima for the plot of B/ux Cus is column specific and the impact of B on the plate height is inversely proportional to the linear velocity of C is column specific and the impact of C on plate height is proportional to the linear velocity versus flow rate. Linear velocity is the flow rate of the mobile phase. e)

Explanation / Answer

The incorrect option is (d), because in order to get the miniumum plate height and the corresponding optimal flow rate, we have to find the minima of the plot H vs flow rate, where H is A + B/ux + Cux

So, the optimal flow rate is the minima of the plot A + B/ux + Cux versus flow rate.

Hope this helps !