Graphene oxide-Fe₃O₄ nanocomposite magnetic solid phase extraction followed by UHPLC-MS/MS for highly sensitive determination of eight psychoactive drugs in urine samples

Graphene oxide–Fe₃O₄ (GO–Fe₃O₄) nanocomposite was synthesized by a facile chemical co-precipitation method. The GO–Fe₃O₄ was used as magnetic sorbent to extract the eight psychoactive drugs from urine samples. The analytes are morphine (MOR), 6-monoacetylmorphine (6-MAM), amphetamine (AMP), methamphetamine (MAMP), codeine, cocaine, dolantin and benzoylecgonine (BZE), which were determined by ultrahigh performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS). This method has high selectivity for the target analytes. The limit of detection (LOD) and limit of quantification (LOQ) were 0.02–0.2 μg L⁻¹ and 0.05–0.5 μg L⁻¹, respectively. The Mandel's fitting test revealed good linearity within all linear ranges. The linear ranges were calculated as 0.05–1000 μg L⁻¹ for AMP, MAMP, cocaine and dolantin; 0.1–1000 μg L⁻¹ for 6-MAM and codein; and 0.5–1000 μg L⁻¹ for MOR and BZE. The recoveries ranged in 80.4–105.5%. The intra-day and inter-day RSDs are in the range of 2.7–13.1% and 3.9–13.7%, respectively. Magnetic solid phase extraction (MSPE) with GO–Fe₃O₄ provides a convenient, rapid and green sample pretreatment method for extracting the target psychoactive drugs from urine. This methodology can be used for simultaneous or individual detection of eight major psychoactive drugs with high sensitivity. This method has high potential in clinical and forensic areas for psychoactive drugs analysis.