Ion exchange technique (IET) to characterise Ag+ exposure in soil extracts contaminated with engineered silver nanoparticles

Abstract

S2 Ion exchange technique (IET) theoryThe principles of IET have been previously outlined 28,30 . Briefly, a sample is passed through a column containing a known mass of a negatively-charged resin (mr) saturated with a readily exchangeable cation, usually Na + . Exchange occurs between the free metal ions in the sample, and the exchange cation on the resin until steady-state equilibrium conditions are achieved (i.e., the concentration of resin-bound metal is constant). The resin-bound metals are then extracted by passing an exact volume of eluate (e.g., 1.5 M HNO3) through the column from which the metal concentration can be determined. The concentration of resin-bound metal, [R-M] (mol g -1 ), is thus determined as: Details of the SP-ICP-MS analysisAs quantification of both the dissolved and nano-particulate forms of Ag are of interest, capturing both dissolved and particle signals is necessary; however, it is doubtful that one dilution/analysis can optimally capture both signals. We have previously developed an approach for the analysis of samples containing high levels of dissolved analyte [36] , whereby a sample dilution series is used as follows:1. The first dilution allows for the capture of the dissolved analyte signal within the dissolved calibration range and above the LoQ.

The toxicity of silver to soil organisms exposed to silver nanoparticles and silver nitrate in biosolids‐amended field soil

“…Dry powdered polyvinylpyrrolidone (PVP)‐coated AgNPs (40 nm, 80% PVP; NanoComposix) were used to make a 10‐g/L dispersion that was used to spike thawed biosolids. Characterization of the dispersion is described elsewhere . Briefly, imaging by transmission electron microscopy (TEM; FEI Tecnai G2‐F20) showed that the particles were well dispersed and spherical and fell within the supplier's size specifications of 38.6 ± 9.8 nm.…”

“…Quality control included analysis of method blanks, internal standards, and the digestion and analysis of external reference samples from the Environment and Climate Change Canada Proficiency Testing Program (SED 98‐5 and 94‐3), as well as a certified reference material (NIST 2711 Montana soil). Extractable Ag + was assessed by applying the ion‐exchange technique (IET) to 0.01 M KNO 3 soil extracts, following procedures described in Schwertfeger et al , which are further described in the Supplemental Data. The KNO 3 extraction procedure is designed to extract readily soluble and electrostatically bound Ag + from the soil, which make up the potentially bioavailable Ag + pool.…”

Analytical applications of single particle inductively coupled plasma mass spectrometry: a comprehensive and critical review

“…In relation to the life cycle of silver nano-enhanced textiles and their environmental implications, the fate and behaviour of pristine Ag nanoparticles in the washing solutions during the laundry process has also been studied. 126 Environmental scenarios for studying the fate of nanoparticles by SP-ICP-MS have included different types of real and synthetic surface waters (lake, [130][131][132][133] river, 134-137 sea [140][141][142] ) and wastewaters, [143][144][145][146][147][148][149][150]275 as well as soils 104,[156][157][158][159][160][161] and sediments. 162,163 Whereas spiked water samples were usually analysed directly or after dilution, soil analysis required the extraction and the separation of the nanoparticles from the soil matrix.…”

Atomic spectrometry update – a review of advances in environmental analysis

“…The sample was first analysed to determine the dissolved Ag concentration and then diluted so that only transient signals from individual Ag NPs were recorded. The same research group assessed the utility of an ion-exchange procedure167 to quantify dissolved Ag ions in soil extracts containing Ag NPs, validating their results by comparison with those obtained with an ISE. They also investigated 168 the efficiency of a variety of reagents for extraction of Ag NPs from soils amended with biosolids.…”