Solid phase extraction of Aflatoxin M1 in milk samples by graphene oxide-poly-L-lysine nanocomposite followed by HPLC

Abstract

ABSTRACT An efficient, novel and green Graphene Oxide-Poly-L-Lysine (GO-PLL) adsorbent was successfully synthesised and used for solid-phase extraction of aflatoxin M1 (AFM1) in liquid milk samples followed by high performance liquid chromatography (HPLC) equipped with fluorescence detector (FLD). The synthesised adsorbent was characterised by Fourier Transform Infrared Spectrophotometry (FT-IR), Field Emission Scanning Electron Microscopy (FESEM), Energy-dispersive X-ray spectroscopy (EDX) and X-Ray diffraction (XRD) analysis. Different parameters affecting the recovery percentage of AFM1 including pH of sample solution, amounts of adsorbent, contact time and desorbent solution (types and volume) were completely investigated and optimised. It was found that, with an enrichment factor of 15.2, the calibration curve is linear in the range of 0.05–4.00 ng ml−1 AFM1 and the limit of detection (LOD) and limit of quantification (LOQ) values were 0.019 and 0.063 ng mL−1, respectively. The relative standard deviations (RSDs) ranged from 4.5% to 5.7% and 4.2% to 6.7% for intra-day and inter-day variations, respectively. Finally, the proposed solid-phase extraction method was successfully applied for determination of trace levels of AFM1 in different milk samples.