Optimization of the extraction of clonazepam and lorazepam using nano-sponge activated carbon and its determination by high-performance liquid chromatography

In the present work, nanos-ponge activated carbon (NSAC) was fabricated and applied for the adsorption of benzodiazepines (BDs) from water and biological samples. The synthesized adsorbent was evaluated by various techniques like Field Emission Scanning Electron Microscope (FESEM), Transmission Electron Microscopy (TEM), and Brunauer, Emmett, and Teller (BET). In research, a dispersive NSAC-ultrasound assisted-microextraction (DUAM) method was used for the extraction of clonazepam (CLO) and lorazepam (LOR) drugs from water and biological samples, and then their concentrations were determined by high performance liquid chromatography (HPLC). In the first step of optimization, seven parameters, including the amount of NSAC (mg), pH, vortex time, time and temperature of the ultrasonic, ionic strength, and volume of desorption solvent (mL) were inquired into by Plackett-Burman design (PBD), and in the second step the significant parameters were optimized by central composite design (CCD). To obtain the best conditions for extracting the drugs mentioned above, linear regression and desirability function (DF) methods were used. After the optimization process, a linear range (LR) and the limits of detection (LOD) of the proposed method were attained. To evaluate the adsorption mechanism and adsorption capacity, different adsorption isotherms were investigated and according to the results Langmuir isotherm model showed highest adsorption capacity (152.6 mg g −1 ). Also, different kinetic models were studied and pseudo second order model (R 2  = 0.989) had the best result.