Liquid Chromatography - Liquid Chromatography Applications 3
The mobile phase is buffered appropriately to complement the dissociation constants of the solutes. A mixture of methanol and acetonitrile is employed, the acetonitrile being used to increase the dispersive interactions in the mobile phase. The reason for the particular solvent mixture is not clear and it would appear that the separation might be achieved equally well by using a stronger solution of methanol alone or a more dilute solution acetonitrile alone. There is no particular advantage to one solvent mixture over another except for the fact that 'waste' acetonitrile produces greater solvent disposal problems than methanol. Another example of the use of reversed phase chromatography for the separation of mixture of growth regulators (a C18 reverse phase column) is shown in figure 58.
Courtesy of Supelco Inc.
Figure 58. The Separation of a Mixture of Growth Regulators on a C18 Reverse Phase C18 Column