Field based speciation of arsenic in UK and Argentinean water samples

Abstract

A field method is reported for the speciation of arsenic in water samples that is simple, rapid, safe to use beyond laboratory environments and cost effective. The method utilises solid phase extraction cartridges (SPE) in series for selective retention of arsenic species, followed by elution and measurement of eluted fractions by inductively coupled plasma mass spectrometry (ICP-MS) for 'total' arsenic. The method is suitable for on-site separation and preservation of arsenic species from water. Mean percentage accuracies (n = 25) for synthetic solutions containing 10 µg l -1 As of arsenite (As III ), arsenate (As V ), monomethylarsonic acid (MA) and dimethylarsinic acid (DMA), were 98 %, 101 %, 94 % and 105 %, respectively. Data are presented to demonstrate the influence of pH and competing anions on the retention of the arsenic species. The cartridges were tested in the UK and Argentina at sites where arsenic was known to be present in surface and groundwaters respectively at elevated concentrations and in challenging matrix conditions. In Argentinean groundwater, 4 to 20 % of speciated arsenic was present as MA and 20 to 73 % as As III . In UK surface waters, speciated arsenic was measured as 7 to 49 % MA and 12 to 42 % as DMA. Comparative data from the field method using SPE cartridges and laboratory method using liquid chromatography coupled to ICP-MS for all water samples provided a correlation of greater than 0.999 for As III and DMA, 0.991 for MA and 0.982 for As V (P < 0.01).

On-site quantitation of arsenic in drinking water by disk solid-phase extraction/mobile X-ray fluorescence spectrometry

“…Ground water contaminated with organic As has been found in recent years [1,2]. Therefore, it is desirable that total As, which is comprised of both inorganic and organic As, in water can be determined.…”

“…Ground water mainly contains inorganic arsenite (As(III)) and/or arsenate (As(V)) ions, which are dissolved from soils and minerals. Although fewer cases are reported, organic As, such as methylarsonic acid (MAA), dimethylarsinic acid (DMAA), phenylarsonic acid (PAA), and diphenylarsinic acid (DPAA) appear in drinking water [1,2] because of microbial activity or human actions. Aromatic As compounds (e.g., p-arsanilic acid (p-AA) and roxarsone (Rox)) are currently used as feed additives for poultry and swine, and there is a possibility that these As compounds could permeate into ground water [3].…”

Evaluation of Arsenic Leaching Potential in Gold Mine Tailings Amended with Peat and Mine Drainage Treatment Sludge

“…Anion concentrations (F − , Cl − , NO 2 − , NO 3 − , PO 4 3− , SO 3 2− , SO 4 2− , Br − , CNO − , S 2 O 3 2− , and SCN − ) were analyzed on filtered samples (0.45 μm) using ion chromatography (Metrohm 881 Compact IC Pro). Speciation of dissolved As species (arsenite [As(III)], arsenate [As(V)], monomethylarsonic acid [MMA(V)], and dimethylarsinic acid [DMA(V)]] was analyzed (within the first hour after sampling) using the solid‐phase extraction cartridge methodology (Watts et al, 2010). The strong anion exchange (SAX) and strong cation exchange (SCX) cartridges were preconditioned to wash the resin and promote the adsorption of As species.…”

Inorganic arsenic speciation by electroanalysis. From laboratory to field conditions: A mini-review

“…Furthermore, having determined all the inorganic forms of arsenic, it is possible to evaluate indirectly the presence of organic forms of As which are frequently found in surface waters [136].…”