Amr Badawey

Solid contact electrodes are widely used in analytical fields due to their outstanding performance over classical ones. However, they showed formation of a water layer affecting stability of those electrodes’ type. Herein, we develop a solid contact ion selective electrode to overcome this common drawback through application of multi-walled carbon nanotubes as a hydrophobic layer between the ion sensing membrane and a glassy carbon electrode. This fine modification improved stability of the electrode via preventing the formation of this water layer. The obtained potential was steady over 30 days with a drift of ∼0.8 mV h−1. The MWCNTs-modified electrode was used for determination of xipamide with a Nernstian slope of −56.01 over a linearity range of 1.0 × 10−5–1.0 × 10−2 mol l−1 and detection limit of 6.0 × 10−6 mol l−1. The proposed sensor was effectively applied for determination of the cited drug in its marketed pharmaceutical dosage form and spiked human plasma.

{Validated ultra-performance liquid chromatography (UPLC) and thin-layer chromatography (TLC) densitometric methods were prescribed for determination of antihypertensive components.To establish and validate rapid and accurate UPLC and TLC densitometric methods for determination of Xipamide and Triamterene in pure and dosage forms.The first method, UPLC, depended on using an Agilent Zorbax Eclipse Plus C8 (50 mm × 2.1 mm, 1.8 μm) column, a mobile phase composed of acetonitrile-water (70 + 30, v/v) adjusted by acetic acid to obtain pH 3, 0.2 mL/min flow rate, and UV detection at 231.4 nm. The second method was a TLC densitometric method. Separation was achieved by using toluene-methanol-ethyl chloride-acetic acid (7 + 2 + 1 + 0.2, v/v/v) as the mobile phase, pre coated silica gel plates as the stationary phase, and UV detection at 300.0 nm.The obtained results were validated and statistically compared with official and reported methods. The obtained results showed high accuracy and reproducible results with excellent mean recoveries for both drugs.The UPLC method showed shorter retention time for both Xipamide (0.88 min) and Triamterene (0.63 min), a lower detection limit of less than 0.055 µg/mL for both drugs with high selectivity, decreased injection volume (1 µL), and a lower flow rate than any HPLC method. Both proposed methods were sensitive, selective, and effectively applied to pure and dosage forms (Epitens®).Unprecedented sensitive, rapid, and reproducible UPLC and TLC methods were developed for selective determination of mixtures of Xipamide and Triamterene, with LOD os less than 0.076 µg/mL for both drugs.}