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Asymmetrical flow field-flow fractionation coupled with a liquid waveguide capillary cell for monitoring natural colloids in groundwater

Kim, Sun Tae, Cho, Hye-Ryun, Jung, Euo Chang, Cha, Wansik, Baik, Min-Hoon, Lee, Seungho
Applied geochemistry 2017 v.87 pp. 102-107
colloids, detection limit, fractionation, geochemistry, groundwater, liquids, monitoring, nanoparticles, nanosilver, South Korea
This paper describes an asymmetrical flow field-flow fractionation (AF4) technique combined with a flow-through cell having a long optical path length, called a liquid waveguide capillary cell (LWCC). The performance of the AF4-LWCC system for separation and spectrophotometric detection of nanoparticles was examined using size-standard silver nanoparticles. The limit of detection for silver nanoparticles of 30 and 60 nm diameter was highly improved to 2.5 and 7.8 μg L⁻¹ (from 220 and 850 μg L⁻¹, respectively) by applying a 100-cm LWCC, compared to a commercial UV/Vis detector. This improvement of detection sensitivity enabled investigating natural nanoparticles in granitic groundwater extracted from an underground research tunnel in the Republic of Korea. Only a small injection volume (0.5 mL) of groundwater was required to obtain the size distributions of trace amounts of natural colloids without pre-concentration. This study demonstrates that the proposed AF4-LWCC system could be applied as a convenient and efficient tool for detection and size-determination of aquatic nanoparticles at trace-level concentrations.