Nanobeads-based rapid magnetic solid phase extraction of trace amounts of leuco-malachite green in Chinese major carps

► Oleic acid coated magnetic nanobeads as solid phase extraction material. ► Extract trace amounts of leuco-malachite green (LMG) from fishery samples. ► Adsorption isotherm model described as Freundlich adsorption isotherm. ► Enrichment efficiency for trace amounts of LMG (less than 0.5 ng/g).