Investigation of the pH effects on the formation of methylated thio-arsenicals, and the effects of pH and temperature on their stability

Conklin, Sean D.; Fricke, Michael; Creed, Patricia A.; Creed, John T.

doi:10.1039/b713145c

Cited by 45 publications

(45 citation statements)

References 43 publications

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“…Thio-methylated As species week) [186]. The authors point out that even at 60 o C it would take 2 days for conversion to occur that exceeds the 95% confidence interval, effectively extracts are stable for this period.…”

Section: Oxo-methylated As Speciesmentioning

confidence: 99%

Measurement of arsenic species in environmental, biological fluids and food samples by HPLC-ICPMS and HPLC-HG-AFS

Maher

Ellwood

Krikowa

et al. 2015

J. Anal. At. Spectrom.

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The importance of measuring arsenic (As) species has been appreciated for a long time mainly because of the wide spread knowledge of arsenic's toxicity and its use as a poison. Increasingly health, environmental and food regulations have been written around As species rather than total concentrations. Knowledge of As speciation is important as the chemical form of As controls its bioavailability, toxicity, mobility and therapeutic benefits. Arsenic is present as inorganic (arsenate, arsenite, thioarsenates), complexed (arsenic glutathionines and phytochelatins), low molecular weight (monomethylarsonate, dimethylarsenite, arsenobetaine, arsenocholine etc.) and high molecular weight ( arsenic hydrocarbons and arsenic phospholipids) species. In this review we cover the intergrity of As species during collection, storage, sample preparation and measurement by HPLC-ICPMS and HPLC-HG-AFS. The major conclusion is that it is essential to ensure that As species, especially in waters and sediments, are not artefacts of the preservation or extraction procedure. Most biota and sediment samples can be stored frozen (-20 o C), but the stability of water and sediment samples is matrix dependent and depends on preservation technique applied. Arsenic cannot be extracted from samples using a single set of conditions but must be optimised for each sample type. Methanol-water mixtures with microwave heating are commonly used to extract polar As species from tissues while As-lipids required a non-polar solvent. Dilute acid can be used to increase the efficiencies of extraction of hard to extract tissue As species. Freeze drying is suitable for the drying of biotic material while sediments should not be dried before analysis. Extraction efficiencies are critically dependent on particle size. Polar As species have a wide variety of ionic characteristics thus complimentary chromatographic 4 Understanding the action of a chemical species in a food stuff or nutritional supplement: As mentioned above, some food regulations require specification of the active ingredient of foodstuffs or supplements. However, another important reason for determining the chemical species is to understand the beneficial action of an element. For example, many food stuffs are promoted for their anti-carcinogenic activity [8]. Evaluation of the role of As in preventing cancers has required the active species to be identified [8,9].Increasingly health, environmental and food regulations have been written around a knowledge of As species rather than total concentrations. In the environment, As is present as inorganic (arsenate (As(V)), arsenite (As(III)), thioarsenates), complexed, (As glutathionines (AsGSH) and phytochelatins (AsPC)), low molecular weight [monomethylarsonate (MA), dimethylarsenite (DMA), arsenobetaine (AB), arsenocholine (AC) etc.] and higher molecular weight (As hydrocarbons and As phospholipids) species (Table 1). Volatile As species (TMAs, As-hydrides) are also produced by bacteria and fungi [10,11].Arsenic is present in all organisms, but is ...

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Section: Oxo-methylated As Speciesmentioning

confidence: 99%

Measurement of arsenic species in environmental, biological fluids and food samples by HPLC-ICPMS and HPLC-HG-AFS

Maher

Ellwood

Krikowa

et al. 2015

J. Anal. At. Spectrom.

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“…Even in case of a hypothetical 100% recovery of each species, inherent procedural species instabilities can cause a shift in species ratio which is difficult to prevent (e.g. instabilities of the oxidation states [14,40], or the thio vs oxo-form [41][42][43]). A control might be possible for a limited set of As-species as they occur in certified reference materials [44,45], despite total As only is certified in the material.…”

Section: Extraction and Preservation Proceduresmentioning

confidence: 99%

Arsenic Speciation Analysis by Ion Chromatography - A Critical Review of Principles and Applications

Ammann¹

2011

AJAC

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Multiple acute and chronic toxicity of arsenic species and its mobilisation from geological deposits into ground and drinking water resources are one of the greatest threats to human health. Arsenic speciation analysis, mostly done by liquid chromatography, is a challenging task which requires an intense high quality work with respect to extraction, preservation, separation, detection and validation. A growing number of As-species and low regulatory limits (10 μg/L) may require more than one speciation method preferably performed by species specific procedures and detectors. Beside As-fractionation for special application there are many selective speciation methods based on high performance separation techniques like capillary electrophoreses, gas and liquid chromatography. Both, fractionation and speciation methods are reviewed. However, the focus is on scopes and limits of ion chromatographic separations, the most frequently used methods. Based on IC-principles the methods applied are critically discussed and recommendations given which should result in more robust and reliable As-speciation.

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“…One hypothesis is that the HS − involved microbial transformation is similar to the chemical reaction between DMA V or MMA V and H 2 S, which were used to synthesise DMMTA V , DMDTA V , MMMTA V and MMDTA V [16,26,[29][30][31]. A second hypothesis is that thiol-organoarsenic species are formed through intermediates dimethylmonothioarsinous acid (DMMTA III ) and monomethylmonothioarsonous acid (MMMTA III ), which is similar to the proposed pathways for the formation of DMMTAV and DMDTAV in rat and red blood cells by Suzuki et al [17,32] and Naranmandura and Suzuki [21].…”

Section: Mechanism For Thiol-organoarsenic Species Formation In Mllmentioning

confidence: 99%

Microbial transformation of arsenic species in municipal landfill leachate

Low

Scott

et al. 2011

Journal of Hazardous Materials

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Investigation of the pH effects on the formation of methylated thio-arsenicals, and the effects of pH and temperature on their stability

Cited by 45 publications

References 43 publications

Measurement of arsenic species in environmental, biological fluids and food samples by HPLC-ICPMS and HPLC-HG-AFS

Measurement of arsenic species in environmental, biological fluids and food samples by HPLC-ICPMS and HPLC-HG-AFS

Arsenic Speciation Analysis by Ion Chromatography - A Critical Review of Principles and Applications

Microbial transformation of arsenic species in municipal landfill leachate

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