Mercury-free and modification-free electroanalytical approach towards bromazepam and alprazolam sensing: A facile and efficient assay for their quantification in pharmaceuticals using boron-doped diamond electrodes

Abstract The boron-doped diamond electrodes (BDDEs) with different dopant levels were applied as advanced, mercury-free and modification-free electroanalytical platforms for simple and reliable quantification of benzodiazepines, bromazepam (BZ) and alprazolam (ALZ). Cyclic voltammetric measurements revealed that the electrode reactions of both analytes were manifested by one irreversible and diffusion-controlled reduction peak at −1.10 V in Britton-Robinson buffer of pH 11 for BZ using lab-made BDDE with 1000 ppm B/C ratio and −0.84 V in BR buffer of pH 5 for ALZ using commercial BDDE with 1000 ppm B/C ratio. Differential pulse voltammetry was used for construction of calibration curves for BZ and ALZ, respectively, with the analytical parameters as follows: the linear dynamic ranges of 1 × 10 −6 –1 × 10 −4 and 8 × 10 −7 –1 × 10 −4  mol/L, the detection limit of 3.1 × 10 −7 and 6.4 × 10 −7  mol/L and the excellent repeatability with the relative standard deviation below 3% for both drugs. The developed methods were applied to analysis of the pharmaceutical tablets with the recoveries from 97.33 to 100.85% for BZ and from 94.14 to 101.32% for ALZ. The usage of BDDEs as advanced electrochemical sensors in drug analysis represents a facile and effective analytical approach which may replace mercury-based sensors and chemically modified electrodes in previous benzodiazepines sensing.