Single particle-inductively coupled plasma-mass spectrometry technology development for metallic nanoparticle characterization in complex matrices

As the rapid growing of nanotechnology, the release of engineered nanoparticles (ENPs) into the environment is inevitable. After entering the real environment, ENPs tend to react with different components of the ecosystem (e.g. water, soil, air, plants) and make their characterization difficult. Analyzing ENPs in these complex matrices still remains as a grand challenge. ENPs characterization is normally the first step of risk assessment. Current analytical techniques have shown some limitations in revealing the unique characteristics of ENPs in complex matrices and reliable analytical techniques are in urgent need. Single particle inductively coupled plasma mass spectrometry (SP-ICP-MS) is an emerging technique capable of determining the ENPs particle size, particle concentration and dissolved analyte concentration and has the potential to fill the analytical gap. In the presented dissertation, several SP-ICP-MS methods were developed and validated to determine the ENPs particle size, size distribution, particle concentration, and dissolved analyte concentration in complex matrices, such as sunscreens and plant tissues. An enzymatic digestion method was also developed to extract ENPs within plant tissues without causing particle dissolution for subsequent SP-ICP-MS quantification. Utilizing enzymatic digestion-SP-ICP-MS, the presence of dissolved cerium in plant shoots exposed to CeO2 NPs hydroponically was confirmed for the first time. Our results also suggest that CeO2 NPs might be taken up by plant roots as ionic cerium. Collectively, SP-ICP-MS has shown great advantages over other techniques, such as high sensitivity, tolerance of complex matrices, high throughput, and informative results (particle size, size distribution, particle concentration, and dissolved analyte concentration) --Abstract, page iv