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  • Non-chromatographic screening procedure for arsenic speciation analysis in fish-based baby foods by using electrothermal atomic absorption spectrometry.

Non-chromatographic screening procedure for arsenic speciation analysis in fish-based baby foods by using electrothermal atomic absorption spectrometry.

Analytica chimica acta (2011-06-28)
Ignacio López-García, Marisol Briceño, Manuel Hernández-Córdoba
ABSTRACT

A procedure for the speciation analysis of arsenic in fish-based baby foods is presented. Inorganic arsenic, methylarsonic acid (MA), dimethylarsinic acid (DMA) and arsenobetaine (AB) were determined by electrothermal atomic absorption spectrometry (ETAAS) using suspensions prepared in a 0.01 mol L(-1) tetramethylammonium hydroxide (TMAH) solution. Speciation is based on the use of three different chemically modified ETAAS atomizers to obtain the analytical signals. Using a palladium salt as the chemical modifier, the signal corresponding to the total arsenic concentration is obtained. When palladium is replaced by Ce(IV), the signal is solely due to inorganic arsenic (III and V)+MA. If no signal is obtained in this latter case, it is possible to distinguish between DMA and AB using a zirconium coated atomizer. The signal obtained in this way is due solely to DMA, and the concentration of AB can be obtained by the difference with the total arsenic content. Determinations by ETAAS require the use of the standard additions method. The limits of detection for the determination of AB, DMA and inorganic arsenic (+MA) are 15, 25 and 50 ng g(-1) expressed as arsenic, respectively. These detection limits are good enough for the procedure to be appropriate for the rapid determination of these compounds, avoiding extraction processes and/or chromatographic separations. Data for commercial samples, as well as for four standard reference materials, are given.

MATERIALS
Product Number
Brand
Product Description

Supelco
Tetramethylammonium sulfate, suitable for ion pair chromatography, LiChropur, ≥99.0% (T)
Sigma-Aldrich
Tetramethylammonium hydroxide solution, 25 wt. % in methanol
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Tetramethylammonium chloride, reagent grade, ≥98%
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Tetramethylammonium hydroxide solution, 10 wt. % in H2O
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Tetramethylammonium hydroxide solution, 25 wt. % in H2O
Supelco
Tetramethylammonium chloride, suitable for ion pair chromatography, LiChropur, ≥99.0% (AT)
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Tetramethylammonium hydroxide solution, ACS reagent
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Tetramethylammonium chloride, BioUltra, for molecular biology, ≥99.0% (AT)
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Tetramethylammonium fluoride, 97%
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Tetramethylammonium bromide, ACS reagent, ≥98.0%
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Tetramethylammonium bromide, 98%
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Arsenobetaine, purum p.a., ≥95.0% (NMR)
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Tetramethylammonium hydroxide pentahydrate, ≥97%
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Tetramethylammonium hydroxide pentahydrate, ≥95.0% (T)
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Tetramethylammonium iodide, 99%
Sigma-Aldrich
Tetramethylammonium chloride solution, for molecular biology
Supelco
Tetramethylammonium bromide, suitable for ion pair chromatography, LiChropur, ≥99.0% (AT)