The Determination of Arsenic Compounds: A Critical Review

Abstract

A large number of publications describe the determination of arsenic in “environmental” samples in the broadest sense, a substantial subset of which focus on plant-based foodstuffs. There is a considerable interest in the inorganic arsenic content of food, especially rice, as there is recent evidence that concentrations may be high enough to exceed acceptable risk thresholds. The methodology for the determination of arsenic in rice is critically evaluated and results (a) for a rice flour reference material (National Institute of Standards SRM 1568a, certified only for total arsenic) and (b) a recent proficiency test (run by the European Commission's Joint Research Centre Institute for Reference Materials and Measurement) are examined. Difficulties with this particular analysis may lie in the sample preparation stages, over which there is still disagreement with regard to species stability, though a simple, hot-water extraction may be sufficient. High performance liquid chromatography separations with plasma-source mass spectrometry detection are popular; however, chromatographic separations are often not adequately described, the enhancement effect of carbon-containing species is often overlooked, and the fate of chlorine-containing species, responsible for an isobaric overlap interference, often obscure. Compound-dependent responses, for which there is a plenty of evidence, are almost never acknowledged or discussed.

Concentrations and speciation of arsenic in New England seaweed species harvested for food and agriculture

“…A weak acidic extraction was also performed on the NIST Rice flour Standard Reference Material (SRM) 1568a (Gaithersburg, MD) for which consensus values have been reported by several studies eg. (Batista et al, 2011; Tyson, 2013). …”

Inorganic Arsenic Determination in Food: A Review of Analytical Proposals and Quality Assessment Over the Last Six Years

“…Among them, here we mention some reviews that are specifically dedicated to arsenic speciation with coupled techniques. 73,78,79,83,105,159 In addition, some more general reviews of analytical techniques include arsenic speciation. Some describe food samples or summarize such aspects as pre-treatment, extraction and preservation of the arsenic species, pre-concentration, how to overcome matrix interference, and specific instrumental conditions (such as types of nebulizers, the use of a dynamic reaction cell, and internal standards).…”

“…The analytical technology to be applied for the assessment of arsenic species, highlighting iAs, is continuously updated and reviewed. 43,[73][74][75][76][77][78][79][80][81][82][83][84] Nearing et al 85 reviewed additional analytical methods suitable for obtaining data to complement the information on arsenic speciation obtained when applying the methods commonly used. Among such complementary methods, electrospray mass spectrometry (ESI-MS) is most useful for identifying or complementing information on several arsenic compounds with more complex molecular structures than those corresponding to iAs species.…”

A colorimetry based, semi-automated portable sensor device for the detection of arsenic in drinking water

“…In some of the developing countries, where the arsenic contamination of water systems is the most severe (such as in Bangladesh or India), this limit is 50 μg/l for drinking water (Flanagan, 2012). While there are several reliable laboratory methods for arsenic detection and quantification in environmental samples -such as high performance liquid chromatography (HPLC) (Ackerman, 2005), inductively coupled plasma mass spectrometry (ICP-MS) (Roje, 2007), atomic absorption spectroscopy (AAS) (Jakariya, 2007), and atomic fluorescence spectroscopy (AFS) (Deng, 2013) as a couple examples -these techniques require expensive and complex instrumentation with highly skilled staff (Tyson, 2013). There is clearly a need for simpler, portable (preferably handheld) devices for on field testing and monitoring.…”