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Rapid Chromatographic Separation of Dissoluble Ag(I) and Silver-Containing Nanoparticles of 1–100 Nanometer in Antibacterial Products and Environmental Waters

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journal contribution
posted on 16.12.2014, 00:00 by Xiao-Xia Zhou, Rui Liu, Jing-Fu Liu
Sensitive and rapid methods for speciation analysis of nanoparticulate Ag (NAg) and Ag­(I) in complex matrices are urgently needed for understanding the environmental effects and biological toxicity of silver nanoparticles (AgNPs). Herein we report the development of a universal liquid chromatography (LC) method for rapid and high resolution separation of dissoluble Ag­(I) from nanoparticles covering the entire range of 1–100 nm in 5 min. By using a 500 Å poresize amino column, and an aqueous mobile phase containing 0.1% (v/v) FL-70 (a surfactant) and 2 mM Na2S2O3 at a flow rate of 0.7 mL/min, all the nanoparticles of various species such as Ag and Ag2S were eluted in one fraction, while dissoluble Ag­(I) was eluted as a baseline separated peak. The dissoluble Ag­(I) was quantified by the online coupled ICP-MS with a detection limit of 0.019 μg/L. The NAg was quantified by subtracting the dissoluble Ag­(I) from the total Ag content, which was determined by ICP-MS after digestion of the sample without LC separation. While the addition of FL-70 and Na2S2O3 into the mobile phase is essential to elute NAg and Ag­(I) from the column, the use of 500 Å poresize column is the key to baseline separation of Ag­(I) from ∼1 nm AgNPs. The feasibility of the proposed method was demonstrated in speciation analysis of dissoluble Ag­(I) and NAg in antibacterial products and environmental waters, with very good chromatographic repeatability (relative standard deviations) in both peak area (<2%) and retention time (<0.6%), excellent spiked recoveries in the range of 84.7–102.7% for Ag­(I) and 81.3–106.3% for NAg. Our work offers a novel approach to rapid and baseline separation of dissoluble metal ions from their nanoparticulate counterparts covering the whole range of 1–100 nm.