Potential Application of Carbon-based Electrical Sensor for the Highly Sensitive Diltiazem HCl Quantification in its Pharmaceutical Products and Biological Samples

Diltiazem (DTZ) hydrochloride, a calcium channel blocker compound, is a very well-known drug used by many clinicians to treat important diseases playing a role in increased morbidity and mortality among adults worldwide, namely hypertension, cardiac arrhythmia, and ischemic heart disease (angina pectoris). These diseases are a common public health concern, implying that the construction of a specific, accurate, and simple sensor for DTZ determination is needed. Herein, an innovative, portable, and sensitive modified carbon paste electrode (MCPE) was seamlessly developed based on the affordable green compound N-bromosuccinimide (NBS) as a sensing material and tricresyl phosphate as a solvent mediator for the voltammetric determination of DTZ. The proposed NBS-MCPE exhibited an excellent electrocatalytic activity towards the oxidation of DTZ molecules in a phosphate buffer solution of pH 5.0 in presence of 20 μM sodium dodecyl sulfate to improve the developed sensor performance. The sensor was found to respond linearly to the DTZ drug over a wide concentration ranging from 1 μM to 300 μM with a low limit of detection. LSV and EIS measurements were also used to scrutinize our sensor, in addition to using scanning electron microscopy and energy dispersive X-ray analysis techniques for its surface morphology inspection before and after soaking in the drug-containing solution. The applicability of the proposed sensor for the rapid, sensitive, and selective determination of DTZ in pharmaceutical preparation and human urine samples was assessed and the obtained results were compared with that of the reported HPLC analytical method.