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The development of analytical technology for inorganic engineered nanoparticles in aquatic environme

Absrtact	This study aims to establish a measuring technique for the inorganic engineered nanoparticles in the aquatic environment, including how to apply the analytical technologies to determine the size distribution and concentration of nanoparticles in water. The average particle sizes of three commercial silver nanoparticles (AgNPs) suspensions measured by dynamic light scattering (DLS) were 79.86, 80.6 and 122 nm for AgNP-A, B and C, and 1663 nm was for AgNP-D. In three wastewater samples and three environmental samples, the particle sizes were multimodal distribution. They have different ion contents, the pH values were around 6.9-8.5 and the conductivities were between 375-11200 μS/cm. The stability of AgNPs was evaluated by adding AgNPs into these samples. Different levels of aggregation and dissolution were observed. Samples should be stored under a lower temperature such as 4℃ without pH adjustment, in the dark, and analyzed as soon as possible. For the pretreatment process, the separation of different particle sizes was suggested by the centrifugation with centrifugal speed of 4000 G for 2 minutes, which has 71 % recovery. The filtration is not suggested as a pretreat process. To quantify the concentration of nanoparticles, the best process is to use 70 % nitric acid to digest samples before inductively coupled plasma-mass spectrometer (ICP-MS) analysis. For the HDC analysis, the correlation between particle size and retention time was determined. pH 10 pure water was chosen as the eluent for the HDC experiment due to its good correlation coefficient. The calibration curves established in pure water can predict the size of AgNPs in different water samples and compare well to the size results from DLS. The size of silver in the recovered eluent could be confirmed by electron microscopy. The results of this study establish a preliminary technique to measure the nanoparticles in aquatic environment and a draft for DLS and HDC analysis.
Keyword	nanoparticles, dynamic light scattering, centrifugation, hydrodynamic chromatography, electron microscopy

Absrtact

This study aims to establish a measuring technique for the inorganic engineered nanoparticles in the aquatic environment, including how to apply the analytical technologies to determine the size distribution and concentration of nanoparticles in water. The average particle sizes of three commercial silver nanoparticles (AgNPs) suspensions measured by dynamic light scattering (DLS) were 79.86, 80.6 and 122 nm for AgNP-A, B and C, and 1663 nm was for AgNP-D. In three wastewater samples and three environmental samples, the particle sizes were multimodal distribution. They have different ion contents, the pH values were around 6.9-8.5 and the conductivities were between 375-11200 μS/cm. The stability of AgNPs was evaluated by adding AgNPs into these samples. Different levels of aggregation and dissolution were observed. Samples should be stored under a lower temperature such as 4℃ without pH adjustment, in the dark, and analyzed as soon as possible. For the pretreatment process, the separation of different particle sizes was suggested by the centrifugation with centrifugal speed of 4000 G for 2 minutes, which has 71 % recovery. The filtration is not suggested as a pretreat process. To quantify the concentration of nanoparticles, the best process is to use 70 % nitric acid to digest samples before inductively coupled plasma-mass spectrometer (ICP-MS) analysis. For the HDC analysis, the correlation between particle size and retention time was determined. pH 10 pure water was chosen as the eluent for the HDC experiment due to its good correlation coefficient. The calibration curves established in pure water can predict the size of AgNPs in different water samples and compare well to the size results from DLS. The size of silver in the recovered eluent could be confirmed by electron microscopy. The results of this study establish a preliminary technique to measure the nanoparticles in aquatic environment and a draft for DLS and HDC analysis.

Keyword

nanoparticles, dynamic light scattering, centrifugation, hydrodynamic chromatography, electron microscopy