Core-shell magnetic zeolite imidazolate framework-8 as adsorbent for magnetic solid phase extraction of brucine and strychnine from human urine.

Core-shell magnetic zeolite imidazolate framework-8 (FeO@PAA@ZIF-8) was successfully synthesized and first employed as adsorbent of magnetic solid-phase extraction (MSPE) for the determination of brucine and strychnine in human urine sample coupled with high performance liquid chromatography. The as-prepared FeO@PAA@ZIF-8 was characterized by transmission electron microscopy, Fourier-transform infrared spectrometry, X-ray diffraction, vibrating sample magnetometer and zeta potential analysis. Main parameters affecting the MSPE efficiency, including amount of adsorbent, sample solution pH, extraction time, ionic strength, desorption solvent, desorption time and desorption volume were further optimized. Under the optimized conditions, the proposed method provided good linearity (5.0-1000.0 μg L) with determination coefficients between 1.0000 and 0.9998, low limits of detection in the range of 1.1-1.2 μg L, and excellent reproducibility with relative standard deviations of less than 7.7%. The intra-day and inter-day precision were 1.5-3.2% and 2.1-7.2%, respectively. Satisfactory spiked recoveries were between97.2% and 115.4% with the relative standard deviations less than 6.3%. The results demonstrated that FeO@PAA@ZIF-8 composite was a promising magnetic adsorbent for the preconcentration of brucine and strychnine in human urine sample.