water is more polar than acetonitrile.but in reverse phase chromatography peaks elute earlier when we increse Acetonitrile.what is the reason.
Answer Posted / michael kwame appenteng
I think it also depends on the constituents of interest, its polarity and whatever parameters you put in place to influence the throughput gradient and resolution. Because in reverse phase chromatography, you have a non-polar (hydrophobic) Stationary phase and a polar aqueous phase (acidified Water as ‘A’ and acidified Acetonitrile as ‘B’). Starting with a higher percentage of the more polar mobile phase (acidified water) will elute the more polar (hydrophilic) constituents, leaving the less polar or hydrophobic constituents adsorbed to the hydrophobic stationary phase. So increasing the percentage of acetonitrile in a way decreases the polarity of the mobile phase so as to elute the less polar or hydrophobic constituents. So once again if your constituents are more hydrophobic or less polar and all other parameters are set right, it works fine.
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