Polyethyleneimine-functionalized carbon dots and their precursor co-immobilized on silica for hydrophilic interaction chromatography.

A new strategy based on synergistic effect of the carbon dots and their precursor was proposed to enhance the selectivity of hydrophilic interaction liquid chromatography (HILIC). In this work, polyethyleneimine (PEI) and PEI-functionalized carbon dots (PEICDs) mix-grafted silica packing material was prepared to act as a novel HILIC stationary phase. Both inner and outer surface of the porous silica are decorated with the mixture of PEI and carbon dots. This stationary phase, namely Sil-PEI/CDs, demonstrate enhanced retention ability and selectivity toward polar analytes, with which 11 nucleosides and nucleobases and 9 ginsenosides can be nicely separated. The Sil-PEI/CDs (RSD 0.12% - 0.54%) exhibited even better stability than the traditional PEI modified stationary phase (RSD 0.39% - 0.87%) within 40 h of continuously elution. And excellent column efficiency was observed from Sil-PEI/CDs (∼65,000 plates/m for cytidine). The strategy of mixed stabilization revealed a new method to prepare good performanced carbon dots based chromatographic column.