Sizing gold nanoparticles using graphite furnace atomic absorption spectrometry

Abstract

The application of nanoparticles (NPs) in science and technology is a wide and fast growing field. Therefore, reliable and straightforward analytical methods are required to enable fast characterization of the size and concentration of NPs in various fields. Recently, we have reported a novel evaluation strategy for data obtained from graphite furnace atomic absorption spectrometry (GFAAS) in order to distinguish silver nanoparticles and ions in solid samples. Thereby, we introduced new parameters “atomization delay” (t_ad) and “atomization rate” (k_at). In the present study, we applied these parameters for the investigation of aqueous suspensions of gold nanoparticles (AuNPs) and solutions of Au(III). The obtained results for k_at and t_ad values show reproducible size correlations for both parameters in a particle size range from 2 to 100 nm. Accordingly, these correlations can be used for size calibration and allow size determination of AuNPs in monodisperse aqueous suspensions. Furthermore, absorbance, t_ad and k_at of 20 nm-sized AuNPs were examined over a concentration range from 1 to 50 μg L⁻¹ revealing that t_ad is the most robust parameter. Finally, multimodal mixtures of 3 to 4 different sizes of AuNPs were studied. Here, deconvolution of the obtained sum peaks led to agreeable accuracy in the determination of AuNP size distribution. Hence, the proposed method has great potential for easy and fast measurement of size distribution of polydisperse AuNP suspensions.