Question

The three chromatograms shown here obtained with 2.5, 1.0 and 0.4 $\mathit{\mu }\mathit{L}$of ethyl acetate injected on the same column under the same conditions. Explain why the peak becomes less symmetrical with increasing sample size.

$\mathbf{2}\mathbf{.}\mathbf{5}\mathit{\mu }\mathit{L}$ $\mathbf{1}\mathbf{.}\mathbf{0}\mathbf{}\mathit{L}$ $\mathbf{0}\mathbf{.}\mathbf{4}\mathit{\mu }\mathit{L}$

Short answer

Here we see in the given figure, the peak jumps up quickly and then gradually falls. This isotherms arise from an overloaded column in which too much solute or sample has been applied to the column. If the column has limited retention capacity, injection of concentrated solute saturates a significant portion of sorption sites, leaving fewer sites available for retention and resulting in a lower k. Such saturation causes the peak maximum to shift to a shorter retention time. The shift forward in retention time increases with increased overload. That’s why the peak becomes less symmetrical with increasing sample size.

Step-by-step solution