Use of electrothermal atomic absorption spectrometry for size profiling of gold and silver nanoparticles

Chemometric approach to discrimination and determination of binary mixtures of silver ions and nanoparticles in consumer products by graphite furnace atomic absorption spectrometry

Extensive use of nanomaterials in consumer products inevitably leads to their release to the environment. For monitoring of the fate of nanoparticles in various matrices, low-cost, simple and rapid size-based methods are required. Graphite furnace atomic absorption spectrometry (GFAAS) can be used for this purpose, because due to the difference between a thermal energy required to atomize ionic silver (Ag⁺) and silver nanoparticles (AgNPs) of different size, the maxima of signals measured by are slightly shifted in time. However, signals are seriously overlapped. Analytical signals of various concentrations of Ag⁺ and differently sized AgNPs in their mixtures were registered under optimized temperature conditions using GFAAS. The research aim was to develop a procedure for quantitative and qualitative analyses of Ag species in the binary mixtures without the need for the deconvolution of their signals into single components. For evaluation of the qualitative composition of the silver forms present in the studied samples, soft independent modeling of class analogy (SIMCA) was applied. The best results were obtained based on the first derivative of absorption signal. The correct identification rate of the Ag forms was only in the range 25-60% depending on the composition of the tested samples, that indicates limitations of this approach. For estimating the concentrations of the Ag forms, partial least squares regression (PLSR) was implemented. The errors levels (expressed as the root mean squared error of prediction of concentration) for mixtures were acceptable and comparable between the studied databases. The developed model was applied for determination of silver species in personal care products. The errors oscillating up to 7.5% for the sum of Ag species are within the limits of the relative prediction error determined from the research studies while building the model.

Characterization of Nanoparticles: Advances

Over the past two decades, the unique properties of engineered nanoparticles (NPs) have placed them at the centre of revolutionary advancements in many sectors of science, technology and commerce. Multi-technique and multi-disciplinary analytical approaches are required to identify, quantify, and characterize the chemical composition, size and size distribution, surface properties and the number and concentration of NPs. In this chapter, an overview of the recent advances in the characterization of NPs will be presented.

Sizing silver nanoparticles in chicken meat using direct slurry sampling graphite furnace atomic absorption spectrometry

Recently, graphite furnace atomic absorption spectrometry (GFAAS) has been suggested as a tool for detection and sizing of metal nanoparticles (NPs) providing several advantages, such as direct analysis of solid samples, high sample throughput, and robust and cost-efficient instrumentation. For this purpose, evaluation of newly introduced criteria of the absorbance signal, namely, atomization delay (t_ad) and atomization rate (k_at), is performed. However, in real samples, NPs are typically stabilized by either engineered coating reagents or natural materials and occur in unknown concentration. Hence, systematic investigation of possible influences of nine different coating reagents and of Ag concentration on the atomization behavior of silver nanoparticles (AgNPs) was studied. Evaluation of absorption signal characteristics revealed no influence of the coating or Ag concentration on the observed parameters. Furthermore, size-dependent measurements gave reproducible size correlation independent from the coating. Validity of sizing AgNPs with the proposed approach was successfully proven by investigation of two reference materials. The found size of 74.3 ± 5.9 nm in RM 8017 (NIST) agrees very well with the certified size of 74.6 ± 3.8 nm. Moreover, AgNP size of 25.1 ± 2.5 nm found by direct slurry sampling GFAAS in matrix reference material "NanoLyse13"-chicken meat homogenate spiked with PVP-AgNPs-was in very good agreement with the reference value of 27.3 ± 5.3 nm as determined by TEM.