Servicenavigation

Project Details

Back

Projekt Print View

Graphite Furnace Atomic Absorption Spectrometry for Sizing Nanoparticles

Subject Area Analytical Chemistry
Term from 2019 to 2024
Project identifier Deutsche Forschungsgemeinschaft (DFG) - Project number 431441727
 
Final Report Year 2024

Final Report Abstract

The aim of the project was to develop a robust, direct and rapid method for determining the size of metal nanoparticles (MNP) using graphite furnace atomic absorption spectrometry (GFAAS). The most important results include kinetic and thermodynamic insights into the atomisation of nanoparticles (NP), which were obtained by in-situ measurements of the temperature profile in the graphite furnace during the atomisation phase. A two-precursor mechanism was found for the atomisation of ionic Au(III), whereas AuNPs show a pseudo-first-order atomisation. The activation energies of atom release from AuNPs increase with particle size up to ~20 nm and approach the heat of sublimation of the bulk material for larger particles. The signal parameter ‘atomisation delay’ therefore shows a logarithmic correlation with the NP size, which answers the question of the underlying mathematical function for size calibration of the GFAAS method. Calibration was successfully carried out for gold and silver NP using known standards. As this is a time-consuming procedure, a mathematical model for simulating calibration data was developed in cooperation with colleagues, with which the experimental calibration time can be reduced by up to 80 %. The investigation of further MNP led to optimised GFAAS methods for the differentiation of zerovalent MNP and metal ions of silver and iron, as well as oxidic NP of copper (Cu2O), zinc (ZnO) and cobalt (Co3O4). The limitation to certain particles is a disadvantage of NP characterisation using GFAAS. A clear strength of the method is its sensitivity for very small NPs with size detection limits for AuNP of ≤ 1.8 nm, AgNP ≤ 1.1 nm and Co3O4 NP ≤ 6 nm. An unexpected finding of the project is the comparison of different graphite sample carriers, whereby the use of solid sampling unit is advantageous. A simulation of the signals of polydisperse MNP suspensions can also be achieved using a further development of the above-mentioned mathematical model for calibration. For the application of the method in real water samples, an enrichment method based on cloud point extraction was developed, which was tested using recovery experiments in spring and tap water. Here too, good values were achieved particularly for small NPs. In summary, the project successfully developed GFAAS-based methods for the characterisation of MNP that are complementary to known methods and are particularly suitable for small NP. In addition, the method is based on a different physical principle than other techniques proposed in the literature, such as element mass spectrometry in single particle mode or light scattering methods. In this way, the project also contributes to analytical quality assurance in NP analysis on the way to reliable and standardised methods.

Publications

 
 

Additional Information

© 2026 DFG Disclaimer / Copyright / Privacy Policy

Textvergrößerung und Kontrastanpassung