Molecularly imprinted polymer -stir bar sorptive extraction of diazepam from natural water

In this work, a molecularly imprinted polymer (MIP)-coated stir bar capable of recognizing diazepam was pre-pared. For this purpose, polytetrafluoroethylene (PTFE) magnets were firstly modified to assure a covalent attachment of polymer to the surface of bar. The resulting MIP was synthesized by bulk polymerization using methacrylic acid as functional monomer, diazepam as template, ethylene glycol dimethacrylate as crosslinker, and azobisisobutyronitrile as initiator. The resultant polymer-modified stir bar was characterized by Fourier -transform infrared spectroscopy and scanning electron microscopy. After investigation of several extraction parameters, a stir-bar-sorptive-extraction (SBSE) method was developed in combination with ion mobility spectrometry (IMS) or ultra-high performance liquid chromatography coupled to mass spectrometry (UHPLC-MS/MS). Quantitative recoveries (>84 %) were obtained for both techniques; however, the UHPC-MS/MS protocol exhibited a better limit of detection (0.4 ng/L) than IMS detection. Indeed, the MIP-SBSE coupled with UHPLC-MS/MS was satisfactorily applied to quantify the presence of traces of diazepam in water samples. On the other hand, the MIP-SBSE using IMS can provide high sensitivity on a millisecond timescale to be used as rapid screening of this target compound in the aforementioned matrices.