Graphite Furnace Atomic Absorption Spectrometry for Sizing Nanoparticles

• Applicant: Professorin Dr. Kerstin Leopold
• Subject Area: Analytical Chemistry
• Term: from 2019 to 2024
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 431441727

The aim of the project is the development of a robust, direct and rapid method for the size determination of metal nanoparticles using graphite furnace atomic absorption spectrometry (GFAAS). The new method will provide reliable results on the size and size distribution of nanoparticles (NPs) in polydisperse suspensions, particularly for the lower nanoparticle size range. The focus is therefore on the development of a reproducible method for size detection and simultaneous concentration determination by means of GFAAS. Here, three crucial aspects will be addressed: 1. Investigation and optimization of the atomization of NPs in the graphite furnace; 2. The development of calibration strategies for size and concentration correlation; and 3. Investigation of the robustness of the method on the basis of complex, real samples. For the first sub-goal, it is important to investigate the kinetics and thermodynamics of the atomization of NPs as a function of concentration and size. For this purpose, the actual temperature curve in the graphite furnace will be recorded in-situ during the atomization phase. Thereby, amongst other parameters the so-called "appearance temperature" of the signals can be determined, from which activation energies can be calculated and the kinetic order of the atomization can be derived. These theoretical findings then serve the second sub-goal, the development of an optimal analytical calibration strategy for both particle size determination and metal concentration. Furthermore, a mathematical method for the deconvolution of signals from polydisperse suspensions will be developed and optimized in order to obtain a rapid method for the size distribution of metal nanoparticles in suspensions. In the third part of the project, more complex samples as well as real samples are to be investigated in which both a heterogeneous size distribution and heteroaggregates may occur. The robustness and possibly limits of the method are determined. The successfully developed and validated method will allow a direct, simple and fast sizing of even very small nanoparticles of real samples, which is difficult or impossible to access with other methods. In addition, the method is based on a different physical principle compared to the techniques of NP analysis proposed in the literature, such as single-particle mass spectrometry or light scattering methods. Thus, the successful project will also make a significant contribution to the analytical quality assurance of nanoparticle analysis on the way to reliable and standardized methods.

• DFG Programme: Research Grants