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Determination of total arsenic and speciation analysis in Mexican maize tortillas by hydride generation – microwave plasma atomic emission spectrometry and high performance liquid chromatography – inductively coupled plasma – mass spectrometry

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Abstract

The determination of total arsenic (tAs), inorganic As (iAs = As(III) + As(V)) and As speciation in Mexican maize tortillas has been undertaken for the first time. Hydride generation – microwave plasma atomic emission spectrometry (HG-MP-AES) with tellurium (sodium tellurite Te(IV)) as the internal standard (IS) yielded tAs results in good agreement with those provided by inductively coupled plasma mass spectrometry (ICP-MS). In seven products from local markets, tAs was found in the range of 21.8–192 μg As kg−1. Analysis of As(III), As(V), MMAs(V), and DMAs(V) by an established anion exchange liquid chromatography – ICP-MS procedure showed that iAs corresponded to 72.3–98.0% of tAs. A non-chromatographic procedure was envisioned for iAs: diluted tortilla extract or calibration solution (pH 9.0) was loaded on a strong anion exchange cartridge modified with silver chloride, iAs fraction was collected and analyzed by HG-MP-AES with IS. For tAs by HG-MP-AES (with IS) the method quantification limit was 47.6 μg As kg−1 whereas for iAs it got worse (95 μg As kg−1) due to the low recovery of this As form in SPE (<30%). In an attempt to eliminate matrix interference, the lower sample volume was loaded on the cartridge and ICP-MS was used for quantification, yielding an improved percentage recovery of 73.4%. On the other part, the iAs recovery was >93% while analyzing natural water with off-line quantification by any of the two atomic spectrometry techniques, indicating that the chemical matrix of tortillas was responsible for poor SPE performance. It is concluded that HG-MP-AES with IS is a cost-effective alternative for the determination of tAs that offers improved precision under a non-rigorous protocol; however, efficient separation/preconcentration of iAs by SPE is still a challenge.

Graphical abstract: Determination of total arsenic and speciation analysis in Mexican maize tortillas by hydride generation – microwave plasma atomic emission spectrometry and high performance liquid chromatography – inductively coupled plasma – mass spectrometry

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Publication details

The article was received on 23 Jan 2017, accepted on 28 Feb 2017, published on 28 Feb 2017 and first published online on 28 Feb 2017


Article type: Paper
DOI: 10.1039/C7AY00224F
Citation: Anal. Methods, 2017, Advance Article
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    Determination of total arsenic and speciation analysis in Mexican maize tortillas by hydride generation – microwave plasma atomic emission spectrometry and high performance liquid chromatography – inductively coupled plasma – mass spectrometry

    M. Guerrero Esperanza, E. Yanez Barrientos, K. Wrobel, F. J. Acevedo Aguilar, A. R. Corrales Escobosa and K. Wrobel, Anal. Methods, 2017, Advance Article , DOI: 10.1039/C7AY00224F

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