Speciation of As(III) and As(V) in Food by Magnetic Dispersive Microsolid Phase Extraction with Dispersive Liquid–Liquid Microextraction with Graphite Furnace Atomic Absorption Spectrometry (GFAAS) Detection

Abstract

Magnetic dispersive microsolid phase extraction (MDMSPE) was coupled with dispersive liquid–liquid microextraction (DLLME) for the separation and preconcentration of arsenic(V) and arsenic(III) prior to graphite furnace atomic absorption spectrometry detection. In the first step, magnetic ZnFe₂O₄ nanotubes were employed for adsorbing arsenic(V). The adsorbent was separated from the aqueous phase by the use of an external magnetic field. Next, arsenic(III) in the upper aqueous phase from MDMSPE was enriched by DLLME. Samples were prepared with artificial gastric juice to avoid inter-conversion of the determined species. The parameters affecting the separation and preconcentration of the determined species were optimized. The detection limits of this protocol were determined to be 1.3 and 2.0 pg mL⁻¹ for arsenic(III) and arsenic(V) with relative standard deviations of 4.5% and 5.6% for a concentration of 1.0 ng mL⁻¹ (n = 9). The enrichment factors were equal to 175-fold for arsenic(III) and 163-fold for arsenic(V). The developed protocol was employed for the determination of arsenic(III) and arsenic(V) in dairy products without preoxidation or prereduction. The recoveries of spiked samples were from 90.8% to 105%. A milk powder certified reference material was analyzed by this approach and the measured results were in good agreement with the certified value.

Keywords:

• Arsenic speciation
• dairy products
• dispersive liquid–liquid microextraction (DLLME)
• graphite furnace atomic absorption spectrometry (GFAAS)
• magnetic dispersive microsolid phase extraction (MDMSPE)

Additional information

Funding

This work was financially supported by the Nature Science Foundation of Hubei Province (Grant No. 2019CFB159) and the Research and Innovation Initiatives of Wuhan Polytechnic University (Grant Nos. 2018J04 and 2018Y07).