Ligand Exchange Chromatography of Nitrophenol Positional Isomers on Co-CMEDA-Silica Gel

Nitrophenols are common pollutants detected in industrial effluents because they are used as basic raw materials in various industrial processes. Due to their toxicity to living things they are chemical species that need to be constantly monitored. Hence, the separation of nitrophenol isomers is very important to determine their levels in the environment. Since technical p-nitrophenol is contaminated with m-nitrophenol and the other aromatic compounds, the selective separation of p-nitrophenol from undesired impurities has become one of the important issues of the paracetamol synthesis. In the present work, a new chromatographic method for the separation of nitrophenol isomers on Co(II)-tris(carboxymethyl)ethylenediamine-silica gel (Co-CMEDA-Silica gel) has been developed using high performance liquid chromatography (HPLC). The chromatographic conditions were optimized by studying the effects of mobile phase composition. The positional isomers of nitrophenol (o-, m-, and p-nitrophenol) could be separated by using ternary mobile phases with water/methanol/acetonitrile in the ratio 5:20:75 under isocratic conditions. The baseline separation of nitrophenol isomers has been achieved successfully with the stepwise gradient elution.