Elucidating the structure of carbon nanoparticles by ultra-performance liquid chromatography coupled with electrospray ionisation quadrupole time-of-flight tandem mass spectrometry

• For the first time, UPLC-ESI-Q-TOF-MS/MS method is established to identify the chemical composition of CNP product.
• The chemical structure of each CNP species are fully characterized by high-accuracy MS and MS/MS analyses.
• The CNP species are reported to exist as non-covalent force linked supramolecular clusters.

A fast and accurate ultra-performance liquid chromatography coupled with electrospray ionisation quadrupole time-of-flight tandem mass spectrometry (UPLC-ESI-Q-TOF-MS/MS) method was developed for the separation and structural elucidation of fluorescent carbon nanoparticles (CNP). The CNP was synthesised from microwave-assisted pyrolysis of citric acid (CA) and 1,2-ethylenediamine (EDA). By using UPLC separation, the CNP product was well separated into ten fractions within 4.0 min. Based on high-accuracy MS and MS/MS analyses, the CNP species were revealed to display six kinds of chemical formulas, including (C10H20N4O5)n, (C8H12N2O5)n, (C16H22N4O9)n, (C6H8O7)n, (C14H18N2O11)n, and (C14H16N2O10)n. In particular, our study revealed for the first time that the CNP species exist as supramolecular clusters with their individual monomers units linked together through non-covalent bonding forces. These findings clearly indicated the usefulness of UPLC-ESI-Q-TOF-MS/MS in identifying the chemical composition of CNP product. It is anticipated that our proposed methodology can be applied to study the structure-property relationships of CNP, facilitating in the production of CNP with desirable spectral features.

A fast and accurate ultra-performance liquid chromatography coupled with electrospray ionisation quadrupole time-of-flight tandem mass spectrometry (UPLC-ESI-Q-TOF-MS/MS) method was developed for the separation and structural elucidation of the fluorescent carbon nanoparticles (CNP) synthesised from microwave-assisted pyrolysis of citric acid (CA) and 1,2-ethylenediamine (EDA). After UPLC separation, the chemical structure and molecular formula of each fractionated CNP species were simultaneously elucidated by high-accuracy MS and MS/MS analyses.Figure optionsDownload as PowerPoint slide