Magnetic dispersive micro-solid phase extraction coupled with dispersive liquid-liquid microextraction followed by graphite furnace atomic absorption spectrometry for quantification of Se(IV) and Se(VI) in food samples

ABSTRACT

In this work, magnetic dispersive micro-solid phase extraction (MDMSPE) coupled with dispersive liquid-liquid microextraction (DLLME) was developed for Se(IV) and Se(VI) followed by graphite furnace atomic absorption spectrometry. MDMSPE involved the use of magnetic ZnFe₂O₄ nanotubes for adsorbing Se(VI). The sorbent was isolated from aqueous phase by using an external magnetic field instead of tedious centrifugation or filtration. In the following step, Se(IV) in the upper aqueous phase of MDMSPE was enriched by DLLME. Samples were prepared with artificial gastric juice to avoid the inter-conversion of target species. The main factors affecting the determination of the analytes were studied in detail. the detection limits of this method were 1.0 and 1.3 pg mL⁻¹ for Se(IV) and Se(VI) with relative standard deviations of 4.6% and 5.1% (c = 1.0 ng mL⁻¹, n = 9), respectively. An enrichment factor of 200 was obtained. This method was used for the detection of Se(IV) and Se(VI) in food samples without any pre-oxidation or pre-reduction operation. A certified reference material of milk powder was analysed by this method, and the determined values were in good agreement with the certified values. Recoveries of spike experiments were in the range of 91.0–107%.

KEYWORDS:

• Magnetic dispersive micro-solid phase extraction
• dispersive liquid-liquid microextraction
• magnetic Znfe₂o₄ nanotubes
• selenium species
• food samples
• graphite furnace atomic absorption spectrometry

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No potential conflict of interest was reported by the author(s).

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This article does not contain any studies with human participants or animals.

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Additional information

Funding

This work was supported by the Nature Science Foundation of Hubei Province [No. 2019CFB159]; Research and Innovation Initiatives of Wuhan Polytechnic University [No. 2018J04 and 2018Y07].