An Automated Magnetic Dispersive Solid-phase Extraction Method for Detection of Cocaine and its Metabolites in Human Urine
In this work, an automated magnetic dispersive solid-phase extraction (AMDSPE) sampling method followed by high performance liquid chromatography-mass spectrometry (HPLC-MS) was developed for quantitative enrichment of COCs from human urine, using modified magnetic nanoparticles as absorbants. The methodolgy was validated according to internationally accepted regulated acceptance criteria in order to establish the validity of the combination of the AMDSPE and use of HPLC-MS for quantitative analysis. The proposed device significantly improved the sampling preparation efficiency with 32 samples in one batch within 40 mins. Optimization of the preparation procedure for the magnetic nanoparticles was explored and the performances of magnetic nanoparticles were characterized by scanning electron microscopy, vibrating sample magnetometer and infrared spectra measurements. Several analytical experimental parameters were studied, including amount of particles and elution solvent. The automated procedure exhibited acceptable linearity( r>0.9972 ) over the concentration range of 10 to 200ng/mL, The limits of detection for the cocaine and cocaine metabolites were 0.23-1.5ng·mL-1 with recoveries ranging from 77.1 to 94.7%. Compared to traditional sampling method, this method is time-saving and environmentally friendly.