title: UHPLC combined with mass spectrometric study of as-synthesized carbon dots samples.
abstract: A fast and green approach to synthesize carbon dots (C-dots) by microwave-assisted pyrolysis of precursor chitosan as the carbon source and glacial acetic acid as the condensation agent has been developed. Ultra-high performance liquid chromatography (UHPLC) has been applied to study C-dots samples prepared with various synthetic conditions including amount of chitosan, concentration of acetic acid and reaction time. All the as-prepared C-dots samples are complex mixtures of C-dots species which can be separated by UHPLC within 16 min. All the separated C-dots peaks display a distinctive absorption bands at 261-271 nm corresponding to the n→π* transition of C=O bond. The obtained chromatograms indicate the composition and complexity of an as-synthesized C-dots sample which is commonly neglected. In addition, high-performance liquid chromatography is employed to fractionate the C-dots sample. The separated C-dots fractions are collected and characterized by photoluminescence (PL) spectroscopy and matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS). The PL spectra of the fractions display emission peaks at 427-446 nm upon excitation at 340 nm. The C-dots fractions are fully anatomized by MALDI-TOF MS, displaying their fragmentation mass ion features and indicating the surface functionalities of C-dots. The findings highlight the virtues of UHPLC to separate and reveal the unique characteristics of individual C-dots 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 Special Administrative Region.
authors.forename: Man Chin
authors.initials: MC
authors.lastname: Paau
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 Special Administrative Region.
authors.forename: Qin
authors.initials: Q
authors.lastname: Hu
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 Special Administrative Region. Electronic address: mmfchoi@gmail.com.
authors.forename: Martin M F
authors.initials: MM
authors.lastname: Choi
mesh_terms: D019342:Acetic Acid / Q000737:chemistry; D002244:Carbon / Q000737:chemistry*; D048271:Chitosan / Q000737:chemistry; D002851:Chromatography, High Pressure Liquid / Q000379:methods*; D007700:Kinetics; D000432:Methanol / Q000737:chemistry; D053758:Nanoparticles / Q000737:chemistry*; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization / Q000379:methods*
chemical_list: D002244:Carbon; D048271:Chitosan; D019342:Acetic Acid; D000432:Methanol
keywords: Carbon dots sample; HPLC; Mass spectrometry; UHPLC