Potentiometric Sensors for the Selective Determination of Benzodiazepine Drug Residues in Real Wastewater Effluents

Abstract

The application of ion-selective electrodes (ISEs) in the detection and determination of environmental pollutants has become a very important mission in the last few years. Two selective and sensitive membrane electrodes were fabricated in the laboratory and intended to evaluate the electrochemical response of bromazepam (BRZ) using phosphotungstic acid (PTA) and sodium tetraphenylborate (TPB) as ion pairing agents. The linearity range of the fabricated electrodes was between 1 × 10−6 M to 1 × 10−3 M. Nernstian slopes of 54 mV/decade and 57 mV/decade were obtained for the BRZ-PTA and BRZ-TPB membrane electrodes, respectively. The performance of the fabricated membranes was optimum in the pH range of 3–6. Optimum electrochemical response was attained through the careful adjustment of all assay settings. The cited method was successfully applied for the selective determination of BRZ in either its pure form or real wastewater samples obtained from a pharmaceutical industrial plant. The main core of novelty in the suggested method lies in the application of the membranes for the sensitive, selective, and economic determination of BRZ in real wastewater effluents without the tedious sample pretreatment procedures. This can make the suggested method considered an eco-friendly method, as it minimizes the use of organic solvents and chemicals used in the pretreatment process.

A Comparative Study between Screen-Printed and Solid-Contact Electrodes for the Stability-Indicating Determination of Bromazepam

“…In our previously published article [ 34 ], liquid-contact electrodes were fabricated using either sodium tetra-phenyl borate or phosphotungstic acid as ion-pairing agents for the detection and quantification of the studied drug in industrial wastewater effluents. In the present work, other types of potential membrane sensors (SPE and SCE) were fabricated to perform another task, which was the stability-indicating determination of BRZ in the presence of its main degradation product.…”

“…The medium pH plays an important role in obtaining the optimum electrode performance, which is ensured in a range of pH from 3.0 to 6.0. A noticed deviation from the standard curves’ linearity was observed at pH levels below three, which can be attributed to the interference encountered by the elevated hydronium ions [ 32 , 33 , 34 ]. On the other hand, at pH values above six, the loss of calibration curve linearity can be attributed to the decrease in BRZ solubility, leading to a marked decrease in electrode potentials [ 53 ].…”

“…The proposed membranes have a wider linearity range with comparable sensitivity, response time, and stability. The fabricated sensors overcome the problem of inner liquid refilling faced in the liquid-contact membranes fabricated in the published methods [ 32 , 33 , 34 ]. The cited potentiometric membrane sensors [ 32 , 33 , 34 , 35 ] were not all used as stability-indicating methods of analysis, which can be considered a marked advantage for the proposed method.…”

“…The fabricated sensors overcome the problem of inner liquid refilling faced in the liquid-contact membranes fabricated in the published methods [ 32 , 33 , 34 ]. The cited potentiometric membrane sensors [ 32 , 33 , 34 , 35 ] were not all used as stability-indicating methods of analysis, which can be considered a marked advantage for the proposed method. Moreover, the proposed method applied the SPE as a stability-indicating tool, which was not found in the other published methods.…”

“…These techniques include ultraviolet (UV)–visible spectroscopy [ 8 , 9 , 10 , 11 , 12 ], fluorimetry [ 8 , 13 ], liquid chromatography (LC) [ 14 , 15 , 16 , 17 , 18 , 19 , 20 , 21 , 22 , 23 , 24 , 25 , 26 ], gas chromatography connected to mass spectrometry (GS/MS) [ 27 , 28 , 29 ], and capillary electrophoresis (CE) [ 30 , 31 ]. Potentiometric membrane sensors, either inner liquid [ 32 , 33 , 34 ] or solid-contact electrodes [ 35 ], were used for the determination of BRZ in its tablet form, biological fluids, and wastewater effluents.…”