Chemometric Analytical Approach for the Cloud Point Extraction and Inductively Coupled Plasma Mass Spectrometric Determination of Zinc Oxide Nanoparticles in Water Samples

Abstract

Cloud point extraction (CPE) with inductively coupled plasma mass spectrometry (ICPMS) was applied to the analysis of zinc oxide nanoparticles (ZnO NPs, mean diameter ~40 nm) in water and wastewater samples. Five CPE factors, surfactant (Triton X-114 (TX-114)) concentration, pH, ionic strength, incubation temperature, and incubation time, were investigated and optimized by orthogonal array design (OAD). A three-level OAD, OA(27) (3(13)) matrix was employed in which the effects of the factors and their contributions to the extraction efficiency were quantitatively assessed by the analysis of variance (ANOVA). Based on the analysis, the best extraction efficiency (87.3%) was obtained at 0.25% (w/v) of TX-114, pH = 10, salt content of 15 mM NaCl, incubation temperature of 45 °C, and incubation time of 30 min. The results showed that surfactant concentration, pH, incubation time, and ionic strength exert significant effects on the extraction efficiency. Preconcentration factors of 62 and 220 were obtained with 0.25 and 0.05% (w/v) TX-114, respectively. The relative recoveries of ZnO NPs from different environmental waters were in the range 64-123% at 0.5-100 μg/L spiked levels. The ZnO NPs extracted into the TX-114-rich phase were characterized by transmission electron microscopy (TEM) combined with energy-dispersive X-ray spectroscopy (EDS) and UV-visible spectrometry. Based on the results, no significant changes in size and shape of NPs were observed compared to those in the water before extraction. The extracted ZnO NPs were determined after microwave digestion by ICPMS. A detection limit of 0.05 μg/L was achieved for ZnO NPs. The optimized conditions were successfully applied to the analysis of ZnO NPs in water samples.

ICP-MS-based characterization of inorganic nanoparticles—sample preparation and off-line fractionation strategies

“…Apart from the low recoveries of the ICP-element standard, high CI values were obtained for both types of samples (ENP suspensions and element standard), indicating that the dissolved fraction was not precisely quantified. Nevertheless, since the approach can in principle be applied to different ENPs (beside Ag, e.g., also Zn, Au, or TiO 2 ) in different matrices [31, 40, 41, 52, 53], a further methodological adaptation of the parameters may potentially enable also an accurate and precise determination of the dissolved fraction. Especially with regard to low concentration of ENPs in complex matrices, this approach may provide a possibility to quantify the concentration of the nanoparticles and the dissolved fraction simultaneously.…”

Investigation of cloud point extraction for the analysis of metallic nanoparticles in a soil matrix

“…These additives were chosen based on previous studies. 16, 19, 42, 43 Generally the added volume was 100 μL to avoid a dilution effect. All reactants were added to the sample with a pipette and measured gravimetrically.…”

Measurement Methods to Detect, Characterize, and Quantify Engineered Nanomaterials in Foods

“…Cloud‐point extraction involves addition of a surfactant such as Triton X and mild heating (40 to 80 °C) when the surfactant phase separates, with the ENM, from the liquid phase. Several cloud point extraction methods for ENMs in water have recently been developed and combined with a variety of analytical schemes, like ICP‐MS, colorimetric, and so forth (Bezerra and others ; Liu and others ; Chao and others ; Wu and Tseng ; Majedi and others ; Hartmann and Schuster ). Solid‐phase extraction (SPE) using a C18 stationary phase is another technique that has been used to extract fullerenes from water, urine, and other matrices (Benn and others ; Pycke and others ) and may be conducive to other types of ENMs.…”