Effect of concentration of ionic liquids on resolution of nucleotides in reversed-phase liquid chromatography

The chromatographic behaviours of nucleotides (inosine 5'-monophosphate, uridine 5'-monophosphate, guanosine 5' monophosphate, and thymine monophosphate disodium salts) on a C-18 column were studied with different types of ionic liwuids (ILs) as additives for the mobile phase in reversed-phase liquid chromatography (RPLC). Three ILs, 1-butyl-3-methylimidazolium tetrafluoroborate ([BMIm][BF4]), 1-ethyl-3-methylimida-zolium tetrafluoroborate ([EMIm][BF4]), and 1-ethyl-3-methylimidazolium methylsulfate ([EMIm][MS]), were used. Eluents were composed of water and methanol (90%/10%, vol) with the addition of 0.5-13.0 mm of results showed that the addition of ILs affects the retention and resolution of the tested compounds. Use of 13.0 mM of [BMIm][BF4] as the eluent modifier resulted in a baseline seperation of nucleotides without requiring gradient elution. This study demonstrates that ILs can be potentially applied as a mobile phase modifier in RPLC.