Highly efficient dispersive liquid-liquid microextraction assisted by magnetic porous carbon composite-based dispersive micro solid-phase extraction for determination of tramadol and methadone in urine samples by gas chromatography-mass spectrometry.

The recognition of opioids, either as prescription drugs or illicit narcotics, is one of the hot challenges in the analytical field, especially in forensic medicine. Here, a rapid and high efficient air-assisted dispersive liquid-liquid microextraction (DLLME) running after a dispersive magnetic solid-phase extraction (MSPE) is developed for simultaneous extraction and preconcentration of tramadol and methadone in urine samples prior to gas chromatography-mass spectrometry (GC-MS) determination technique. The samples were first mixed with a new magnetic and porous adsorbent, based on a metal-organic framework (MOF) derived NH2-functionalized Fe3O4 nanoparticles-carbon nanocomposite (NH2-Fe3O4@C). Then, the eluent, containing the retrieve analytes, was directly applied as the disperser solvent, along with dichloromethane extracting solvents, to perform DLLME. The combination of MSPE, using the new high surface area sorbent, with a high-performance DLLME resulted in exceptional enrichment factors and extraction recoveries. Under the optimized conditions, linear ranges of 0.1-30 ng mL-1 and 0.1-35 ng mL-1, and detection limits of 73 and 32 pg mL-1, were obtained for tramadol and methadone, respectively. The developed system was utilized for the extraction and preconcentration of tramadol and methadone in some urine samples of suspected drug users, with a reasonable reproducibility (2.4-4.5%). The results were in good agreement with those of the official HPLC/MS-MS technique.