Calculation of Maximum Injection Volumes

In order to be able to calculate the maximum volume that can be injected in a column, one has to differentiate between solutes with no retention, retained solutes dissolved in the mobile phase, and retained solutes dissolved in a solvent with lower elution strength than the mobile phase. Using sample solvents with higher elution strength than the mobile phase is usually not recommended, as it may result in broad peaks or double peaks, or at least would require small injection volumes. 

Maximum injection volume without extra band broadening is given by 

Example For k = 3, the maximum volume in the example above will be 20 pi. 

Example For a solute with very high retention in the low solvent strength (kg = 10), with k = 3 in the mobile phase and with the column above, Vmax = 600 pi. 

The focusing assumes no mass overload and no mass displacement effects. 

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