Synthesis of octadecylamine-derived carbon dots and application in reversed phase/hydrophilic interaction liquid chromatography

In order to make up for the deficiencies of traditional C18 column for separating strong polar compounds, combined with the good hydrophilicity of carbon dots (CDs), novel octadecylamine-derived CDs denoted as C18-CDs are designed, synthesized and applied in RPLC/HILIC mixed-mode chromatography with good separation performance towards both hydrophobic and hydrophilic compounds. C18-CDs are synthesized by simple one-step solvothermal method using octadecylamine and citric acid as carbon sources, and C18-CDs with proper polarity are collected through column chromatography purification. This C18-CDs decorated silica column showed good separation performance for polycyclic aromatic hydrocarbons and alkylbenzenes under RPLC mode. Hydrophilic compounds including sulfonamides, nucleosides and nucleobases also achieved good resolution in HILIC mode. Hydrophobic and pi-pi stacking interactions play major retaining roles in RPLC, whereas hydrophilic partitioning and hydrogen bond interactions turn to the main retention interactions under HILIC mode. This C18-CDs/SiO2 column was applied for the fast detection of chloramphenicol in milk without complex sample pretreatment process. Quantitative relationship between the peak area and the concentration of chloramphenicol was established with linear equation of A = 1677c + 173. Satisfactory spiked recoveries in the range of 94.1-109.0% were obtained. This work not only proposes a simple method for improving the polarity of C18 column through forming octadecane into CDs, but also provides novel CDs with certain hydrophobicity/hydrophily suitable for mixed-mode chromatography. (C) 2021 Elsevier B.V. All rights reserved.

Automated summary

The novel octadecylamine-derived CDs, C18-CDs, were successfully designed, synthesized, and applied in RPLC/HILIC mixed-mode chromatography, showing good separation performance for both hydrophobic and hydrophilic compounds. The C18-CDs/SiO2 column demonstrated efficient separation for various compounds under different modes, indicating its potential for further research in mixed-mode chromatography.