Magnetic solid-phase extraction of Fast Green dye based on magnetic nanoparticles (GO/Co3O4/Fe3O4) prepared by photo-irradiation method

The magnetic nanoparticles (MNPs) of (GO/Co3O4/Fe3O4) were synthesized, characterized, and then utilized to prepare magnetic solid-phase extraction (MSPE), introducing a new method for the determination of Fast Green dye coupled with UV–visible spectrophotometry. The results demonstrated that Fast Green dye was adsorbed on GO/Co3O4/Fe3O4 MNPs and was released using 1 mL of 0.01 N NaOH. Under optimal conditions, the linear range was 0.5–6 mg/L and the limit of detection (LOD) was 0.2648. The high values of the preconcentration factor (25) and enhancement factor (10.5789) indicate that the MSPE process has concentrated the Fast Green dye by 25 times and made it 10.5789 times more sensitive. This highlights the successful extraction and concentration of Fast Green dye into a small volume of 1 mL of 0.01 N NaOH through the MSPE process. Furthermore, the GO/Co3O4/Fe3O4 MNPs sorbent exhibited reusability for up to five cycles. The application of greenness assessment tools (AES, GAPI, and AGREE) confirmed that MSPE can be considered a green chemistry method.