Stability of inorganic and methylated arsenic species in laboratory standards, surface water and groundwater under three different preservation regimes

Stetson, Sarah; Erickson, Melinda L.; Brenner, J.; Berquist, Emily; Kanagy, Christopher J.; Whitcomb, Susan Melissa

doi:10.1016/j.apgeochem.2020.104814

Cited by 8 publications

(8 citation statements)

References 50 publications

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“…The Fe (oxyhydr)oxide phases formed from Fe(II) oxidation and Fe(III) hydrolysis during the freezing and thawing processes have been shown to sorb As from solution, changing the total concentration and the species distribution. 50,51 This was consistent with the observation of high As species transformation rate and loss of As species in Fe-rich waters, 21,39 even though storage at −20 °C (freezing) was reported to be useful for Fe-poor samples. 52 A further problem with Fe(II) in reducing groundwaters is that, in the presence of air, Fe(III) formed by the rapid oxidation of Fe(II) at circum-neutral pH 15 is able to covert iAs(III) to iAs(V) rapidly.…”

Section: Precipitation Of Fe-oxides and Recrystallizationsupporting

confidence: 81%

Large Quantity EDTA Addition and Cold Storage in Dark Recommended for Preserving Inorganic Arsenic Speciation in Reducing Groundwater

Duan,

Liu,

Yang

et al. 2024

ACS EST Water

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Analysis of inorganic arsenic (iAs) species, arsenite (iAs(III)) and arsenate (iAs(V)), is recommended by authorities to select treatment technologies for noncompliant domestic well water. However, the effectiveness of various preservation methods for iAs species, including those recommended by regulatory authorities, varies with the added preservatives on-site, groundwater chemistry, and storage conditions. Here, 14 preservation methods, which include three strong acids, a range of concentrations of ethylene diamine tetraacetic acid disodium salt (EDTA) and acetic acid (HAc), three storage temperatures, and two kinds of sample bottles, were tested with 62 groundwaters spanning a wide range of chemical compositions from multiple aquifers in northwestern and southern China. Addition of EDTA to a final concentration of 20 mmol/L and storage in opaque bottles and in the dark at 4 °C preserved iAs species up to 60 days. Preservation was achieved through forming Fe-EDTA and Mn-EDTA complexes accompanied by lowering of the pH from 7.0 ± 0.5 to 5.2 ± 0.4 and eliminating photooxidation. Users are recommended to start with the best performing protocol involving adding EDTA to 20 mmol/L on-site, adjusting the EDTA dose considering the initial Fe and Mn concentrations, and final pH. Regulatory authorities are urged to examine iAs preservation protocols in their standard methods for speciation analysis.

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Section: Precipitation Of Fe-oxides and Recrystallizationsupporting

confidence: 81%

Large Quantity EDTA Addition and Cold Storage in Dark Recommended for Preserving Inorganic Arsenic Speciation in Reducing Groundwater

Duan,

Liu,

Yang

et al. 2024

ACS EST Water

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“…Field spikes were treated separately from laboratory spikes to assess the variability contributed by the field procedure and sample handling and storage prior to analysis but was not intended to be a full hold-time study. A separate hold-time study is reported [25] which demonstrated that there can be interconversion of As species within 15 days of sampling in certain samples and others can be stable for more than 90 days. There was wider variability in recoveries of field spikes than laboratory spikes (Table SI-3) but mean recoveries were similar.…”

Section: Methods Validationmentioning

confidence: 99%

“…All data generated in this study are available at https://doi.org/10.5066/P9A66FQ4 [16] . Hold time studies for both standards and environmental samples are reported in a companion paper [25] .…”

Section: Acknowledgementsmentioning

confidence: 99%

Determination of four arsenic species in environmental water samples by liquid chromatography- inductively coupled plasma - tandem mass spectrometry

2021

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Robust and sensitive methods for monitoring inorganic and organic As species As(III), As(V), dimethylarsinate (DMA), and monomethylarsonate (MMA) in environmental water are necessary to understand the toxicity and redox processes of As in a specific environment. The method is sufficiently sensitive and selective to ensure accurate and precise quantitation of As(III), As(V), DMA, and MMA in surface water and groundwater samples with As species concentrations from tens of nanograms per liter to 50 µg/L without dilution of the sample. Mean recoveries of the four species spiked into reagent water, surface water and groundwater and measured periodically over three months ranged from 87.2 % to 108.7 % and relative standard deviation of replicates of all analytes ranged from 1.1 % to 9.0 %. A PRP-X100 column and nitrate/phosphate mobile phase was used to separate As(III), As(V), DMA, and MMA in 0.45 µm filtered surface water and groundwater matrices. Oxygen was used in the collision cell of the inductively coupled plasma-mass spectrometer with MS/MS mode to shift the measured As mass from 75 to 91. The analytical performance of the method and figures of merit including detection limits, precision, accuracy, and interferences when applied to surface water and groundwater matrices were investigated.

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“…To perform confirmatory analysis by HPLC-ICP-MS to validate the SPE field speciation procedure (Reilly et al 2010) a 10 mL sample was collected following filtration (0.45 µm) with the addition of 500 µL of 0.25 M ethylenediaminetetraacetic acid to preserve methylarsenicals (EDTA dipotassium dihydrate, Fluka Analytical, Sigma-Aldrich, Ireland) and stored in the dark at 4 °C (McCleskey et al 2004;Ujević et al 2010;Stetson et al 2021).…”

Section: Speciation Of Arsenicmentioning

confidence: 99%

“…Arsenate forms the oxyanions H 2 AsO 4 − and HAsO 4 − in oxidising environments in natural waters, while arsenite forms the oxyanions H 3 AsO 3 0 and H 2 AsO 3 − in reducing environments with the degree of protonation depending on pH (Garelick et al 2009;Herath et al 2016). Organic arsenic species may be present in groundwater because of biological activity, but their relative concentrations may be negligible (Cullen and Reimer 1989;Smedley and Kinniburgh 2013;Schreiber 2021;Stetson et al 2021). These methylated organic forms of arsenic include the pentavalent dimethylarsinic acid (DMA V ) and methylarsonic acid (MA V ) which are stable mammalian metabolites (Lord et al 2012).…”

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confidence: 99%

Occurrence, Geochemistry and Speciation of Elevated Arsenic Concentrations in a Fractured Bedrock Aquifer System

McGrory

Henry

Conroy

et al. 2021

Arch Environ Contam Toxicol

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The presence of elevated arsenic concentrations (≥ 10 µg L−1) in groundwaters has been widely reported in areas of South-East Asia with recent studies showing its detection in fractured bedrock aquifers is occurring mainly in regions of north-eastern USA. However, data within Europe remain limited; therefore, the objective of this work was to understand the geochemical mobilisation mechanism of arsenic in this geologic setting using a study site in Ireland as a case study. Physicochemical (pH, Eh, d-O2), trace metals, major ion and arsenic speciation samples were collected and analysed using a variety of field and laboratory-based techniques and evaluated using statistical analysis. Groundwaters containing elevated dissolved arsenic concentrations (up to 73.95 µg L−1) were characterised as oxic-alkali groundwaters with the co-occurrence of other oxyanions (including Mo, Se, Sb and U), low dissolved concentrations of Fe and Mn, and low Na/Ca ratios indicated that arsenic was mobilised through alkali desorption of Fe oxyhydroxides. Arsenic speciation using a solid-phase extraction methodology (n = 20) showed that the dominant species of arsenic was arsenate, with pH being a major controlling factor. The expected source of arsenic is sulphide minerals within fractures of the bedrock aquifer with transportation of arsenic and other oxyanion forming elements facilitated by secondary Fe mineral phases. However, the presence of methylarsenical compounds detected in groundwaters illustrates that microbially mediated mobilisation processes may also be (co)-occurring. This study gives insight into the geochemistry of arsenic mobilisation that can be used to further guide research needs in this area for the protection of groundwater resources.

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Stability of inorganic and methylated arsenic species in laboratory standards, surface water and groundwater under three different preservation regimes

Cited by 8 publications

References 50 publications

Large Quantity EDTA Addition and Cold Storage in Dark Recommended for Preserving Inorganic Arsenic Speciation in Reducing Groundwater

Large Quantity EDTA Addition and Cold Storage in Dark Recommended for Preserving Inorganic Arsenic Speciation in Reducing Groundwater

Determination of four arsenic species in environmental water samples by liquid chromatography- inductively coupled plasma - tandem mass spectrometry

Occurrence, Geochemistry and Speciation of Elevated Arsenic Concentrations in a Fractured Bedrock Aquifer System

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