Evaluation of reduced graphene oxide-based nanomaterial as dispersive solid phase extraction sorbent for isolation and purification of aflatoxins from poultry feed, combined with UHPLC–MS/MS analysis

Abstract

Poultry feed comprises cereals and their by-products and is vulnerable to aflatoxins contamination. This study utilised reduced graphene oxide–titanium dioxide (rGO–TiO₂) nanomaterial as a dispersive solid phase extraction (d-SPE) adsorbent to extract, enrich and purify aflatoxins (aflatoxin B1, aflatoxin B2, aflatoxin G1 and aflatoxin G2). The synthesis of rGO–TiO₂ nanomaterials through hydrothermal process and characterisation by transmission electron microscopy, scanning electron microscopy, Brunauer–Emmett–Teller (BET) and X-ray diffraction reveals that the nanomaterials have a single-layer structure embedded with TiO₂ nanoparticles. The matrix-spiked technique was employed for the extraction process, optimisation of d-SPE, and analytical method validation. The most appropriate extraction solvent was acetonitrile/water/formic acid (79/20/1, v/v/v), with 30 min of extraction time assisted by ultra-sonication. The optimised d-SPE parameters were: 50 mg of rGO–TiO₂ as sorbent amount, 2% methanol as the sample loading solvent, 30 min as adsorption time, and absolute ethanol as the washing reagent. The d-SPE method exhibited good desorption efficiency with 3 mL of acetonitrile/formic acid (99/1, v/v) and 20 min desorption time. After validation, the UHPLC–MS/MS analytical method has an acceptable range of specificity, linearity (R² ≥ 0.999), sensitivity (LOQ 0.04–0.1 µg kg⁻¹), recoveries (74–105% at three matrix-spiked levels) and precision (RSD 1.5–9.6%). Poultry feed samples (n = 12) were pretreated by this method to extract, enrich and analyse aflatoxins, which were detected in all poultry feed samples. The contamination levels were within the permissible limits.

Keywords:

• Aflatoxins
• dispersive solid phase extraction
• reduced graphene oxide
• poultry feed
• ultra high-performance liquid chromatography–tandem mass spectrometry

Acknowledgements

This research was supported by the National Major Scientific and Technological Project for “Significant New Drugs Development” (2018ZX09201010).

Disclosure statement

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

Additional information

Funding

This research was supported by the National Major Scientific and Technological Project for “Significant New Drugs Development” (2018ZX09201010).