Magnetic porous carbon derived from a zinc-cobalt metal-organic framework: A adsorbent for magnetic solid phase extraction of flunitrazepam

Nanoporous carbon that contains magnetic cobalt nanoparticles (Co-NPC) was fabricated by direct carbonization of a Zn-Co bimetallic zeolitic imidazolate framework. After carbonization, the magnetic Co-NPs are well dispersed in the porous carbon matrix, with the result that the Co-NPC displays strong magnetism. The Co-NPC possesses a high specific surface area, large pore volumes and a microstructure comprised of mesopores and macropores. This results in fast molecular diffusion of the analytes along with excellent adsorption. The Co-NPC was used as a magnetic adsorbent for the enrichment of the benzodiazepine drug flunitrazepam (rohypnol) from tea and Ginger ale prior to high-resolution mass spectrometric analysis. The calibration plot is linear (with a correlation coefficient of >0.9869) in the 1 to 500 ng mL−1 concentration range. The limits of detection are 0.2 ng mL−1 for Ginger ale and 1.0 ngmL−1 for Arizona Tea samples, respectively, which is lower by about 4 orders of magnitude than those reported in the literature.