Determination of silver ions at submicrogram‐per‐liter levels using anodic square‐wave stripping voltammetry

Abstract

Square‐wave stripping voltammetry at a carbon paste electrode was used to develop a method to measure silver ions at concentrations as low as 0.2 μg/L in surface waters. Sample matrix was found to be an important factor affecting the measurement results. Because of these matrix effects, the peak shape of the voltammograms varied, and multiple stripping peaks for silver were observed. Total charge provided a more reliable measure of deposited silver than did peak height. The precision of the method for the analysis of standard reference materials containing silver was estimated to be 7.2% relative SD at 1 SD using a 95% confidence interval of the individuals. A full factorial experiment was performed to determine how the following factors affected measurement variability: electrode, renewal of the carbon paste electrode surface, silver ion concentration, preparation of standards and samples, and day‐to‐day variability. Samples of lake and river water were collected and analyzed for silver ion. In all samples the measured concentration of silver ion was <0.2 μg/L, whereas the concentration of total silver was typically >0.5 μg/L. Spiking experiments showed that the constituents of the river water samples had a greater ability to bind (remove) silver ion than did the lake water.

Bioaccumulation and toxicity of silver compounds: A review

“…Chem. 18,1999 H.T. Ratte values under field conditions are probably due to the fact that the accumulated quantity was related to the total silver concentration in the surrounding medium rather than to the dissolved silver concentration; only the bioavailable part of the total silver concentration can really be accumulated.…”

“…Obviously, the perception of high silver toxicity has long been due to the fact that most laboratory toxicity experiments tested AgNO 3 , which readily dissolves, releasing the highly toxic free Ag ϩ ion. Because of enhanced heavy metal analyses and experimental techniques (e.g., the ultraclean technique [14][15][16][17][18]), a better understanding of total silver concentrations in various environmental compartments and, in particular, of silver speciation has emerged. This research has demonstrated that apparent toxicity is related to individual silver species rather than total silver concentration.…”

Electrochemical determination of Ag-ions in environment waters and their action on plant embryos

“…Combinations of these techniques can recover between 90 and 99% of the silver on site. Silver that remains in solution is discharged in the wastewater from the facility [3,4]. In water silver (I) exists as various inorganic and organic compounds.…”

“…The commonly used techniques for the silver ions determination in biological samples are atomic absorption spectrometry, inductively coupled plasma mass spectrometry, stripping voltammetry and others [4,[13][14][15][16][17]. An exception to this is the use of potentiometry or ion selective electrodes [18][19][20][21][22].…”

Influence of water quality on silver toxicity to rainbow trout (Oncorhynchus mykiss), fathead minnows (Pimephales promelas), and water fleas (Daphnia magna)

“…The current equations governing acute freshwater limits for most heavy metals are based on hardness, which has been shown to overestimate the toxicity of metals (including silver) to freshwater organisms [7]. Currently, ambient silver may be measured as total silver (by graphite furnace atomic absorbtion spectroscopy [GFAAS]), filterable silver (by filtration through a 0.45-m filter followed by GFAAS or an equivalent method), or ionic silver (by anodic stripping voltammetry [8]). Either total or filterable measures of silver must be less than a calculated value from the U.S. Environmental Protection Agency (U.S. EPA) criteria maximum concentration (CMC) equation:…”