A simple and low cost home-made zeolite bulk-modified screen printed electrochemical sensors (ZY/SDS/MSPE) have been constructed for simultaneous determination of methocarbamol (MTH) and paracetamol (PAR) in pharmaceutical dosage form and biological fluids. The enhanced electrochemical performance of ZY/SDS/MSPE compared to unmodified electrodes is most probably due to the synergistic effect of zeolite crystals. The sensor has been utilized as a disposable sensor for quantification of MTH and PAR near the physiological pH by square wave voltammetry. Under optimal experimental conditions, calibration curves showed excellent linearity over the concentration range from 4.00 × 10⁻⁷ −1.00 × 10⁻⁴ M for both compounds with detection limits of 8.6 × 10⁻⁸ and 8.0 × 10⁻⁸ M for MTH and PAR, respectively. The proposed ZY/SDS/MSPE has been applied successfully for simultaneous determination of MTH and PAR in presence of ascorbic acid (AA) and uric acid (UA). Furthermore, excellent peak potential separation between MTH and diclofenac (DIF), which is present as co-formulated in other pharmaceutical formulations, has been achieved. The electrode exhibited satisfactory accuracy (100 ± 2%) and precision (RSD ≤2%) for MTH and PAR.

Disposable all solid-state screen printed ion selective electrode was developed for the assay of daclatasvir (DCV) in pharmaceutical formulation and spiked human urine. The sensor is based on daclatasvir-tetraphenyl borate (DCV-TPB) as a sensing element. Incorporation of multiwall carbon nanotubes (MWCNTs) into the ion selective membrane was found to influence the sensor sensitivity. A MWCNTs containing membrane exhibited a Nernstian slope of 31.0±1 mV/decade over a wide concentration range from 1 × 10-5 to 1 × 10-2 M DCV (r2 = 0.9999) with a LOD of 8.5 × 10-7 M in a pH 3.3 compared to a slope of 27.5±1 mV/decade, over the concentration range from 1 × 10-4 to 1 × 10-2 M DCV for MWCNTs-free ion selective membrane. The response time of the electrode was <15 sec, and the potential drift was ≤0.23 ¼V/min against 330.0 ¼V/min for a coated glassy carbon electrode. Further characterizations including reproducibility, chronopotentiometry and selectivity were examined. The electrode showed high selectivity to DCV against common interfering compounds. The electrode was applied for the assay of daclatasvir in pharmaceutical formulation and spiked urine sample with a high accuracy (±2%) and precision (%RSD <2).

A vital analytical procedure is that comprises less experimental variables, but maintains high efficiency, accuracy and selectivity for one or more than one target analyte. Commonly, ion selective electrodes are prepared and optimized for determination of one ion. Herein, we describe a double-use all-solid-state planar ion selective platform for determination of two incompatible drugs, namely, diclofenac (anion) and clomiphene (cation). The ion exchanger which is the key for thermodynamic ion exchange equilibrium was formed in-situ in the membrane phase utilizing drugs lipophilicity and drug-drug interaction. Drugs interaction and complex formation was elucidated by UV spectroscopy. Also, the morphology of the sensor was characterized using SEM. The effect of membrane plasticizer on the magnitude of the potentiometric response of the sensor was investigated. A sensor with tricresyl phosphate showed a Nernstian slope of 59.1 ± 0.5 and 57.8 ± 1.2 mV/decade for diclofenac and clomiphene, respectively. The electrode showed a high selectivity to diclofenac and clomiphene over common pharmaceutical excepients. The sensor was applied for determination of diclofenac and clomiphene in a variety of pharmaceutical dosage forms and drinking water with a high accuracy (±2%) and precision (%RSD ≤ 2.5).