Preparation of electrospun polyacrylonitrile/Ni-MOF-74 nanofibers for extraction of atenolol and captopril prior to HPLC-DAD

Electrospun nanofibers of polyacrylonitrile/Ni-metal-organic framework 74 (PAN/Ni-MOF-74) were prepared and utilized as a novel sorbent for spin-column micro-solid-phase extraction (SC-mu SPE) of atenolol (ATN) and captopril (CAP). The electrospun nanofibers were characterized by field emission scanning electron microscopy, energy-dispersive X-ray spectroscopy, Fourier transform infrared spectroscopy, and X-ray diffraction analysis. Ni-MOF-74 nanoparticles in the polymeric network of polyacrylonitrile considerably enhance the extraction efficiency of the electrospun sorbent due to providing hydrophobic, hydrogen bonding, and pi-pi interactions with the target analytes. The entire procedure, including sample loading, washing, and eluting of the target analytes was performed by centrifugation of the spin column. The extracted analytes were then quantified by high-performance liquid chromatography with a diode array detector. Various parameters affecting extraction efficiency were optimized using the one-variable-at-a-time method. Under optimum conditions, the calibration plots were linear in the range 0.5-500 ng mL(-1) for ATN and 0.3-500 ng mL(-1) for CAP with r(2) > 0.999. Limits of detection of 0.15 and 0.13 ng mL(-1) were obtained for ATN and CAP, respectively. The intra-assay relative standard deviation for five replicate measurements was <= 7.8. The relative recoveries for both drugs were within the range 82.6-98.9%. The applicability of the method was successfully investigated for measuring the target drugs in biological fluids and wastewater. The results indicate proper accuracy and analytical performance of the proposed method.