A multi-walled carbon nanotube-based magnetic molecularly imprinted polymer as a highly selective sorbent for ultrasonic-assisted dispersive solid-phase microextraction of sotalol in biological fluids.

A modified multiwalled carbon nanotube-based magnetic molecularly imprinted polymer (MWCNT-MMIP) was synthesized and applied for selective extraction and preconcentration of sotalol (SOT) in biological fluid samples by using ultrasonic-assisted dispersive solid-phase microextraction (UA-DSPME). The synthetic particles were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), Brunauer-Emmett-Teller (BET) analysis, vibrating sample magnetometry (VSM) and Fourier transform infrared spectroscopy (FTIR). The screening of UA-DSPME was preliminarily performed by Plackett-Burman design (PBD) and, subsequently, central composite design (CCD) under response surface methodology (RSM) was used individually for evaluation of the significant factors and their possible interaction effects on the adsorption process. Batch mode adsorption studies were performed to evaluate the adsorption kinetics, adsorption isotherms, and selective recognition of MWCNT-MMIPs. The adsorption equilibrium of SOT using MWCNT-MMIPs could be well-defined with the Langmuir isotherm model and the maximum adsorption capacity was calculated to be 79.36 mg g-1. Under optimized conditions, the SOT was selectively and effectively extracted in real biological samples and good linearity was obtained with correlation coefficients (R2) over 0.996 and the detection limit (S/N = 3) was 0.31 ng mL-1. The average recoveries of the spiked human urine and plasma samples at four concentration levels of SOT ranged from 94.60-102.50 and 97.40-101.60 percent, respectively, and the relative standard deviation was found to be lower than 4.50%. The results illustrated that the proposed MWCNT-MMIPs@UA-DSPME extraction method coupled with HPLC-UV determination could be applied for sensitive and selective analysis of trace SOT in biological fluid samples.