Preconcentration and trace determination of copper (II) in Thai food recipes using Fe3O4@Chi-GQDs nanocomposites as a new magnetic adsorbent

- A new Fe3O4@Chi-GQDs nanocomposite was synthesized and characterized.
- Fe3O4@Chi-GQDs can be used for ultrasound assisted-magnetic solid phase extraction.
- The particle size of the magnetic adsorbent is very small (9 nm).
- The material exhibits excellent ability for preconcentration of copper in foods.
- The adsorbent can be reused seven times with high extraction efficiency.

This study describes the preparation, characterization, and application of a new magnetic chitosan-graphene quantum dots (Fe3O4@Chi-GQDs) nanocomposite as an adsorbent for the preconcentration of Cu(II) in Thai food recipes or the so-called “Som Tam” (green papaya salad) prior to determination by inductively coupled plasma-optical emission spectrometry. The spectroscopic and magnetic properties along with the morphology and thermal property were analyzed using FTIR, EDX, XRD, TGA, VSM, and TEM. Preconcentration optimizations including pH, dosage of adsorbent, adsorption-desorption time, concentration and volume of elution solvent, sample volume and enrichment factor, and reusing time were investigated. Good linearity was obtained ranging from 0.05 to 1500 µg L−1 with correlation coefficient of 0.999. Limit of detection was 0.015 µg L−1. Relative recoveries of 85.4-107.5% were satisfactorily obtained. This Fe3O4@Chi-GQDs has high potential to be used as preconcentration method and can be reused 7 times with high extraction efficiency.

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