Ion Pair Chromatography is a method for improving the separation of charged analytes. In the resolution of organic ions with conventional HPLC methods, use of ion pair reagents can enhance peak shape and resolution when common remedies such as modifying eluent ratios or changing stationary phases fail.
Ion pair chromatography relies upon the addition of ionic compounds to the mobile phase to promote the formation of ion pairs with charged analytes. These reagents are comprised of an alkyl chain with an ionizable terminus:
When used with common hydrophobic HPLC phases in reversed-phase mode, ion pair reagents can be used to selectively increase the retention of charged analytes.