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

Abstract

The characterization of manufactured nanoparticles (MNPs) in environmental samples is necessary to assess their behavior, fate and potential toxicity. Several techniques are available, but the limit of detection (LOD) is often too high for environmentally relevant concentrations. Therefore, pre-concentration of MNPs is an important component in the sample preparation step, in order to apply analytical tools with a LOD higher than the ng kg−1 level. The objective of this study was to explore cloud point extraction (CPE) as a viable method to pre-concentrate gold nanoparticles (AuNPs), as a model MNP, spiked into a soil extract matrix. To that end, different extraction conditions and surface coatings were evaluated in a simple matrix. The CPE method was then applied to soil extract samples spiked with AuNPs. Total gold, determined by inductively coupled plasma mass spectrometry (ICP-MS) following acid digestion, yielded a recovery greater than 90 %. The first known application of single particle ICP-MS and asymmetric flow field-flow fractionation to evaluate the preservation of the AuNP physical state following CPE extraction is demonstrated.

Single-particle ICP-TOFMS with online microdroplet calibration for the simultaneous quantification of diverse nanoparticles in complex matrices

“…31 Triton is a non-ionic polyoxyethylene surfactant that is sometimes used in procedures to extract NPs. 38 Because Triton and other surfactants alter a sample's physical parameters such as viscosity and surface tension, 35 it could affect nebulized droplet formation and thus q plasma . For each matrix, we ran a series of matrix concentrations each spiked with the same nominal concentration of 100nm Au NPs and 1 ng mL −1 Cs.…”

Assessing the interactions of metal nanoparticles in soil and sediment matrices – a quantitative analytical multi-technique approach

“…Given the low environmental concentrations of ENMs, pre-concentration methods are often needed for analytical techniques with higher limits of quantification (LOQ). Thus, our previous study focused on cloud point extraction applied to a complex soil matrix (extract) spiked with gold nanoparticles (AuNPs) 21 . In the present study, however, spiked analyte concentrations are sufficiently high (above expected environmental levels) to negate the need for pre-concentration, as the purpose here is to validate the general analytical approach and to demonstrate its potential to interrogate ENM-matrix interactions.…”

“…Analytically, we employ hyphenation of AF4 with tandem detection methods, including ultra-violet visible (UV-Vis) absorption, multi-angle light scattering (MALS) and ICP-MS, which have proven particularly valuable and flexible in our previous work 20, 21 . This coupling provides information about the size, but also about the nature and composition of NPs under relevant conditions, and with minimal perturbation of the analyte.…”

Performance of sp-ICP-TOFMS with signal distributions fitted to a compound Poisson model

“…To accomplish this, either the instrument sensitivity can be increased or the dissolved background can be reduced. For example, dissolved background can be reduced through simple sample dilution, ion-exchange purication, 9,10 NP extraction, 11 or separation methods. [12][13][14] Despite the effectiveness of the different approaches to remove dissolved analyte species, there will always be a non-zero background and, for the detection of small NPs that produce low ion-count signals, analyte sensitivity becomes the major limitation.…”