Preconcentration and determination of chlordiazepoxide and diazepam drugs using dispersive nanomaterial-ultrasound assisted microextraction method followed by high performance liquid chromatography

•In this study a novel method was developed for extraction of benzodiazepines.•The synthesized nanomaterial characterized by XRD and TEM.•Affective factors on the proposed method were optimized by RSM.•FFD and CCD design was applied for optimization process.•Optimized method was applied for determination of chlordiazepoxide and diazepam.

Benzodiazepines (BDs) are used widely in clinical practice, due to their multiple pharmacological functions. In this study a dispersive nanomaterial-ultrasound assisted- microextraction (DNUM) method followed by high performance liquid chromatography (HPLC) was used for the preconcentration and determination of chlordiazepoxide and diazepam drugs from urine and plasma samples. Various parameters such as amount of adsorbent (mg: ZnS-AC), pH and ionic strength of sample solution, vortex and ultrasonic time (min), and desorption volume (mL) were investigated by fractional factorial design (FFD) and central composite design (CCD). Regression models and desirability functions (DF) were applied to find the best experimental conditions for providing the maximum extraction recovery (ER). Under the optimal conditions a linear calibration curve were obtained in the range of 0.005–10 μg mL−1 and 0.006–10 μg mL−1 for chlordiazepoxide and diazepam, respectively. To demonstrate the analytical performance, figures of merits of the proposed method in urine and plasma spiked with chlordiazepoxide and diazepam were investigated. The limits of detection of chlordiazepoxide and diazepam in urine and plasma were ranged from 0.0012 to 0.0015 μg mL−1, respectively.