Polyvinylcaprolactam Functional Carbon Dots on Silica as Green Stationary Phase for Per Aqueous Liquid Chromatography

Green separation has garnered escalating attention in recent years. The goal is to develop stationary phases that provide sufficient retention and separation in pure water or high-content water as the mobile phase. Here, vinylcaprolactam (VCl) polymer-modified silica (SiO 2 @poly(VCl)) was prepared through ATRP technique, and then carbon dots (CDs) were further bonded at the end of poly(VCl) chains, fabricating SiO 2 @poly(VCl)-CDs hydrophilic stationary phase. Characterization of SiO 2 @poly(VCl)-CDs demonstrated that poly(VCl) and CDs were successfully decorated onto SiO 2 surface. Since the acrylamide groups in poly(VCl) and charged amino as well as carboxyl groups in CDs, the packed SiO 2 @poly(VCl)-CDs column was employed for per aqueous liquid chromatography (PALC) using nucleic bases, organic acids, and β-agonists as test solutes, resulting in good separation. Most importantly, the baseline separation for those solutes was achieved by using 100% water as the mobile phase. Beyond that, using 100% water of green separation condition, SiO 2 @poly(VCl)-CDs column had the superior ability in separation and determination of cyclic adenosine monophosphate (cAMP) from jujube. Accordingly, our devised SiO 2 @poly(VCl)-CDs stationary phase possesses the excellent separation ability toward polar compounds under pure water, having the property of green chromatography.