Hydrophobic and hydrophilic selectivity of a multifunctional carbonyldiimidazolium/dodecyl modified silica stationary phase

In this work, a new strategy of simultaneously grafting two different functional ligands onto the silica surface was adopted to prepare a carbonyldiimidazolium/dodecyl dual-functionalized silica stationary phase (Sil-CDI-DD) by recycling the discarded commercial C18 columns as the raw materials. A full characterization of the waste silica-C18, the calcined silica, the acidified silica and the new packing materials was done to explore the feasibility of recycling the waste chromatographic columns. Hydrophobic and hydrophilic selectivity of the obtained Sil-CDI-DD was specifically investigated, and retention mechanisms in reversed-phase and hydrophilic interaction chromatography modes were discussed. The experimental results showed that the perfect combination of carbonyldiimidazolium and long-chain alkyl groups commendably enhanced the separation selectivity and efficiency of the versatile Sil-CDI-DD, which could provide multiple interaction sites for diverse target analytes, thereby contributing to the favorable resolution of hydrophilic nucleosides/nucleobases and weak polar environmental endocrine disruptors, including alkylphenols, bisphenols, steroid hormones and phthalates.