Capillary electrophoretic study of amine/carboxylic acid-functionalized carbon nanodots

Qin Hu, Man Chin Paau, Yan Zhang, Wan Chan*, Xiaojuan Gong, Lei Zhang, Martin M F CHOI

*Corresponding author for this work

Research output: Contribution to journalJournal articlepeer-review

64 Citations (Scopus)


Capillary zone electrophoresis (CZE) coupled with UV absorption and laser-induced fluorescence detections has been applied to study the complexity of carbon nanodots (C-dots) products synthesized with microwave-assisted pyrolysis of citric acid (CA) and 1,2-ethylenediamine (EDA). The effects of pH and concentration of run buffer on the CZE separation of C-dots are studied in detail. The optimal acetate run buffer (30mM, pH 3.6) is subsequently employed to investigate the effect of reaction time and mole ratio of amine (NH2) to carboxylic acid (COOH) moieties of the precursors on the C-dots species present in C-dots products. Our results confirm that the synthesis of C-dots could be improved by lengthening the microwave irradiation time and optimizing the initial mole ratio of NH2/COOH in the precursors. Negatively charged C-dots are obtained only when the amount of CA exceeds that of EDA, i.e., the mole ratio of NH2/COOH is 0.25-0.80. By contrast, when the quantity (mole) of NH2 in EDA is equal to or larger than that of COOH in CA, only positively charged and neutral C-dots species are formed, inferring that the C-dots species are predominantly covered by the surface-attached ammonium and amido moieties. This work highlights the merit of CZE to identify the composition of an as-prepared C-dots product which is pretty much dependent on the mole ratio of NH2/COOH. It is anticipated that our CZE methodology will open a new avenue in optimizing the synthetic conditions for producing specific C-dots of desired composition.

Original languageEnglish
Pages (from-to)234-240
Number of pages7
JournalJournal of Chromatography A
Publication statusPublished - 23 Aug 2013

Scopus Subject Areas

  • Analytical Chemistry
  • Biochemistry
  • Organic Chemistry

User-Defined Keywords

  • Amine and carboxylic acid functionality
  • Carbon dots
  • Synthesis


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