Quantification of amine functional groups on silica nanoparticles: a multi-method approach
| Autor: | Ying Sun, Brian R. Coleman, Vinod Balhara, Oltion Kodra, Gregory P. Lopinski, Filip Kunc, Mohammad Raza, Maohui Chen, Andreas Brinkmann, Linda J. Johnston |
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| Rok vydání: | 2019 |
| Předmět: |
Chemistry
Inorganic chemistry General Engineering Bioengineering 02 engineering and technology General Chemistry 010402 general chemistry 021001 nanoscience & nanotechnology 01 natural sciences Atomic and Molecular Physics and Optics 0104 chemical sciences Nanomaterials chemistry.chemical_compound X-ray photoelectron spectroscopy Solid-state nuclear magnetic resonance Covalent bond Reagent Ninhydrin Proton NMR General Materials Science Amine gas treating 0210 nano-technology |
| Zdroj: | Nanoscale Advances. 1:1598-1607 |
| ISSN: | 2516-0230 |
| Popis: | Surface chemistry is an important factor for quality control during production of nanomaterials and for controlling their behavior in applications and when released into the environment. Here we report a comparison of four methods for quantifying amine functional groups on silica nanoparticles (NPs). Two colorimetric assays are examined, ninhydrin and 4-nitrobenzaldehyde, which are convenient for routine analysis and report on reagent accessible amines. Results from the study of a range of commercial NPs with different sizes and surface loadings show that the assays account for 50–100% of the total amine content, as determined by dissolution of NPs under basic conditions and quantification by solution-state ¹H NMR. To validate the surface quantification by the colorimetric assays, the NPs are modified with a trifluoromethylated benzaldehyde probe to enhance sensitivity for quantitative ¹⁹F solid state NMR and X-ray photoelectron spectroscopy (XPS). Good agreement between the assays and the determination from solid-state NMR is reinforced by elemental ratios from XPS, which indicate that in most cases the difference between total and accessible amine content reflects amines that are outside the depth probed by XPS. Overall the combined results serve to validate the relatively simple colorimetric assays and indicate that the reactions are efficient at quantifying surface amines, by contrast to some other covalent modifications that have been employed for functional group quantification. |
| Databáze: | OpenAIRE |
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