Author(s): Khosravi K, Hoque ME, Dimock B, Hintelmann H, Metcalfe CD, Khosravi K, Hoque ME, Dimock B, Hintelmann H, Metcalfe CD, Khosravi K, Hoque ME, Dimock B, Hintelmann H, Metcalfe CD, Khosravi K, Hoque ME, Dimock B, Hintelmann H, Metcalfe CD
Abstract Share this page
Abstract Titanium dioxide (i.e. TiO(2)) in nano-form is a constituent of many nanomaterials that are used in sunscreens, cosmetics, industrial products and in biomedical applications. Quantification of TiO(2) nanoparticles in various matrixes is a topic of great interest for researchers studying the potential health and environmental impacts of nanoparticles. However, analysis of TiO(2) as Ti(4+) is difficult because current digestion techniques require use of strong acids that may be a health and safety risk in the laboratory. To overcome this problem, we developed a new method to digest TiO(2) nanoparticles using ammonium persulfate as a fusing reagent. The digestion technique requires short times to completion and optimally requires only 1 g of fusing reagent. The fusion method showed >95\% recovery of Ti(4+) from 6 μg mL(-1) aqueous suspensions prepared from 10 μg mL(-1) suspension of different forms of TiO(2,) including anatase, rutile and mixed nanosized crystals, and amorphous particles. These recoveries were greater than open hot-plate digestion with a tri-acid solution and comparable to microwave digestion with a tri-acid solution. Cations and anions commonly found in natural waters showed no significant interferences when added to samples in amounts of 10 ng to 110 mg, which is a much broader range of these ions than expected in environmental samples. Using ICP-MS for analysis, the method detection limit (MDL) was determined to be 0.06 ng mL(-1), and the limit of quantification (LOQ) was 0.20 ng mL(-1). Analysis of samples of untreated and treated wastewater and biosolids collected from wastewater treatment plants yielded concentrations of TiO(2) of 1.8 and 1.6 ng mL(-1) for the wastewater samples, respectively, and 317.4 ng mg(-1) dry weights for the biosolids. The reactions between persulfate ions and TiO(2) were evaluated using stoichiometric methods and FTIR and XRD analysis. A formula for the fusing reaction is proposed that involves the formation of sulfate radicals. Copyright © 2011 Elsevier B.V. All rights reserved.
This article was published in Anal Chim Acta
and referenced in Research & Reviews: Journal of Botanical Sciences