title: High-performance liquid chromatographic and mass spectrometric analysis of fluorescent carbon nanodots.
abstract: Amino/hydroxyl-functionalized fluorescent carbon nanodots (C-NanoD) are conveniently synthesized based on hydrothermal carbonization of chitosan at 180°C. Dialysis membranes with small cut-off masses (500-1000 Da) were found useful for removing the side-products and low molecular mass species to purify the C-NanoD product. Herein, reversed-phase high-performance liquid chromatography (RP-HPLC) has been successfully applied to fractionate the C-NanoD product. The elution order of the C-NanoD species present in the sample follows approximately their core sizes from small to large. The separated C-NanoD fractions are collected and characterized by UV absorption spectroscopy, photoluminescence (PL) spectroscopy, matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS), and transmission electron microscopy (TEM). All the C-NanoD fractions display a distinctive absorption band at 300 nm, attributing to the n→π* transition of C=O bond. The PL spectra of the fractions display emission peaks at 400-415 nm which are slightly red-shifted with their increase in relative molecular masses. The C-NanoD fractions are fully anatomized by MALDI-TOF MS, displaying their fragmentation mass ion features. The core sizes of some selected C-NanoD are determined as 1.6, 1.8, 2.5, and 3.1 nm by TEM which are in consistent with their HPLC elution order. The findings highlight the virtues of RP-HPLC to fractionate and reveal the unique characteristics of individual C-NanoD species present in an as-synthesized C-NanoD product which may have potential applications in the fields of bioanalysis, bioimaging, catalysis, chemosensing, energy storage, and optoelectronics device.
authors.affiliation: Institute of Environmental Science, and School of Chemistry and Chemical Engineering, Shanxi University, Taiyuan 030006, China.
authors.forename: Xiaojuan
authors.initials: X
authors.lastname: Gong
authors.affiliation: Partner State Key Laboratory of Environmental and Biological Analysis, and Department of Chemistry, Hong Kong Baptist University, 224 Waterloo Road, Kowloon Tong, Hong Kong, China.
authors.forename: Qin
authors.initials: Q
authors.lastname: Hu
authors.affiliation: Partner State Key Laboratory of Environmental and Biological Analysis, and Department of Chemistry, Hong Kong Baptist University, 224 Waterloo Road, Kowloon Tong, Hong Kong, China.
authors.forename: Man Chin
authors.initials: MC
authors.lastname: Paau
authors.affiliation: Institute of Environmental Science, and School of Chemistry and Chemical Engineering, Shanxi University, Taiyuan 030006, China.
authors.forename: Yan
authors.initials: Y
authors.lastname: Zhang
authors.affiliation: Institute of Environmental Science, and School of Chemistry and Chemical Engineering, Shanxi University, Taiyuan 030006, China.
authors.forename: Lei
authors.initials: L
authors.lastname: Zhang
authors.affiliation: Institute of Environmental Science, and School of Chemistry and Chemical Engineering, Shanxi University, Taiyuan 030006, China.
authors.forename: Shaomin
authors.initials: S
authors.lastname: Shuang
authors.affiliation: Institute of Environmental Science, and School of Chemistry and Chemical Engineering, Shanxi University, Taiyuan 030006, China. Electronic address: dc@sxu.edu.cn.
authors.forename: Chuan
authors.initials: C
authors.lastname: Dong
authors.affiliation: Partner State Key Laboratory of Environmental and Biological Analysis, and Department of Chemistry, Hong Kong Baptist University, 224 Waterloo Road, Kowloon Tong, Hong Kong, China. Electronic address: mfchoi@hkbu.edu.hk.
authors.forename: Martin M F
authors.initials: MM
authors.lastname: Choi
mesh_terms: D002244:Carbon / Q000032:analysis*; D002851:Chromatography, High Pressure Liquid / Q000379:methods*; D056148:Chromatography, Reverse-Phase / Q000379:methods; D005453:Fluorescence; D013058:Mass Spectrometry / Q000379:methods*; D053758:Nanoparticles / Q000032:analysis*; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization / Q000379:methods
chemical_list: D002244:Carbon
keywords: Analytical separation; Carbon dots species; Chitosan