Development of a pH-assisted homogeneous liquid-liquid microextraction method using a switchable solvent for the electrochemical determination of nitrazepam

Nitrazepam is a hypnotic benzodiazepine drug used in the treatment of moderate to severe insomnia which has sedative and motor impairing properties as well as anxiolytic, amnestic, anticonvulsant, and skeletal muscle relaxant properties. in continuation of previous work [1], we wish to report a simple and efficient kind of homogeneous liquid-liquid microextraction based on an acid–base reaction using switchable-hydrophilicity solvent for the quantification of nitrazepam. Analyte is extracted into the N,N-dipropylamine as an extraction solvent via assistance of HCl and NaOH as pH adjustment reagents. After evaporation of solvent, extracted nitrazepam was analyzed by voltammetric methods. The influences of experimental factors on the extraction efficiency (type of acid, volume of acid, extraction temperature, ratio of the volume of organic solvent/water, pH of solution, volume of NaOH, extraction time, and salt addition) were investigated and optimized using voltammetric methods. Under optimal conditions, the calibration curve was plotted in the range of 0.03-300 ng/mL and the detection limit (at S/N=3) was obtained 9 ng/L. Finally, the proposed method has been applied successfully for the determination of nitrazepam in diluted urine samples.