Preconcentration and determination of diazepam in pharmaceutical and biological samples by graphene oxide based on dispersive solid phase microextraction

Graphene oxide (GO) has a great potential to use as an adsorbent in sample preparation procedures. In this research, GO was used as an effective adsorbent in a simple GO-based dispersive micro-solid phase extraction technique coupled with high-performance liquid chromatography-UV detector (HPLC-UV) for the determination of diazepam. The prepared GO was characterized by X-ray diffraction (XRD), Fourier transform infrared (FT-IR) spectroscopy and scanning electron microscope (SEM) techniques. Various experimental parameters affecting the extraction recovery were investigated and optimized. Under the optimized conditions, a linear response was obtained in the concentration range of 1–100 ng mL−1 with a detection limit of 0.20 ng mL−1. It also showed reproducible results with relative standard deviation of 3.6 and 1.3 % for 10 and 80 ng mL−1 of Zn (II), respectively. The method was successfully applied to the diazepam analysis in biological and pharmaceutical samples.