| Nanoparticles (NPs), especially metal nanoparticles (M-NPs) have been used increasingly in various areas due to their unique properties. For example, AuNPs are widely used in biomedical imaging, cancer therapy and diagnostics and biological and chemical sensing. For these applications, physical size, shape and elemental composition are highly important properties that influence the performance of these NPs, and thus it is critical to prepare nanoparticles with the lowest size and shape dispersion. Furthermore, the increasing use of M-NPs will inevitably result in their widespread release into the environment. Therefore, in addition to the beneficial use of NPs, concerns about adverse effects regarding their release, toxicity and pathways in the environment have also been raised. Several studies have demonstrated that the concentration, size, and form of M-NPs, as well as their corresponding metal ions concentrations impact their toxicity. Moreover, many studies have reported that nanoparticles possess higher toxicities in comparison with metal ions of the same element. Therefore, it is of considerable interest to develop new methods for the size characterization and quantification of metal nanoparticles and their corresponding metal ions for gaining a better understanding of the fate and transfer process of the nanoparticles, and it is of great significant in the field of environmental risk assessment.The main contents of the present dissertation are as follows:1. Metal nanoparticles (NPs) determination has recently attracted considerable attention due to the continuing boom of nanotechnology. In this study, a novel method for separation and quantitative characterization of NPs in aqueous suspension was established by coupling thin layer chromatography (TLC) with laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS). Gold nanoparticles (AuNPs) of various sizes were used as the model system. It was demonstrated that TLC not only allowed separation of gold nanoparticles from ionic gold species by using acetyl acetone/butyl alcohol/triethylamine (6:3:1, v/v) as the mobile phase, but it also achieved the separation of differently sized gold nanoparticles (13 nm,34 nm and 47 nm) by a using phosphate buffer (10 mM, pH= 6.8), Triton X-114 (0.4%, w/v), EDTA (10 mM) as the mobile phase. Various experimental parameters that affecting TLC separation of AuNPs, such as the pH of the phosphate buffer, the coating of AuNPs, the concentrations of EDTA and Triton X-114, were investigated and optimized. It was found that separations of AuNPs by TLC displayed size dependent retention behavior with good reproducibility, and the retardation factors (Rf value) increased linearly with decreasing nanoparticle size. The analytical performance of the present method was evaluated under optimized conditions. The limits of detection were in the tens of pg range, and repeatability (RSD, n=7) was 6.3%,5.9% and 8.3% for 30 ng of 13 nm AuNPs,34 nm AuNPs and 47 nm AuNPs, respectively. The developed TLC-LA-ICP-MS method has also been applied to the analysis of spiked AuNPs in lake water, river water and tap water samples.2. The tremendous increasing use of engineered nanoparticles has raised concerns about their impact on the environment and in biological systems. Among them, silver-containing and gold-containing material is of high industrial interest and of manifold use in consumer products. Therefore, analytical methods are urgently needed for the reliable determination of gold and silver nanoparticles and their ionic counterparts. In this study, a novel method for separation and quantitative characterization of NPs in aqueous suspension was established by coupling thin layer chromatography (TLC) with laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS). It was found that TLC could allow simultaneous separation of differently sized gold nanoparticles (AuNPs) (13 nm,41 nm), silver nanoparticles (AgNPs) (10 nm,40 nm) with their ionic counterparts by using sodium dihydrogen phosphate anhydrous (0.5mM), Triton X-114 (0.05%, w/v), sodium dodecyl sulfate (0.013%, w/v), and formic acid (0.05%, w/v) as the mobile phase. Compared with the established method for the separation of metal nanoparticles, the developed TLC method is relatively simple and rapid.3. In this study, a simple, rapid and sensitive method for the determination of size and mass concentration of gold nanoparticles (AuNPs) in aqueous suspension was established by direct coupling of thin layer chromatography (TLC) with catalyzed luminol-H2O2 chemiluminescence (CL) detection. For this purpose, a moving stage was constructed to scan the chemiluminescence signal from TLC separated AuNPs. The proposed TLC-CL method allows the quantification of differently sized AuNPs (13nm, 41nm and 100nm) contained in a mixture. Various experimental parameters affecting the characterization of AuNPs, such as the concentration of H2O2, the concentration and pH of the luminol solution, and the size of the spectrometer aperture were investigated. Under optimal conditions, the detection limits for AuNP size fractions of 13 nm,41 nm and 100 nm were 38.4 pg,35.9 pg and 39.6 pg, with repeatabilities (RSD, n=7) of 7.3%,6.9% and 8.1% respectively for 10 ng samples. The proposed method was successfully applied to the characterization of AuNP size and concentration in aqueous test samples. |
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