Two Versatile Pencil Graphite-Polymer Sensor Electrodes Coupled with Potentiometry and Potentiometric Titration Methods: Profiling Determinations of Vitamin V in Tablets and Urine Samples

• Published in: Sensors (Basel, Switzerland) Vol. 22; no. 23; p. 9128
• Main Authors: Hassan, Abeer M E, El Hamd, Mohamed A, El-Maghrabey, Mahmoud H, Mahdi, Wael A, Alshehri, Sultan, Batakoushy, Hany A
• Format: Journal Article
• Language: English
• Published: Switzerland MDPI AG 24.11.2022; MDPI
• Subjects: Acids; Analysis; Cations; Cyclic guanylic acid; Dioctyl phthalate; Drug dosages; Electrical measurement; Electrodes; Enzymes; Erectile dysfunction; Graphite; Humans; Hydrogen-Ion Concentration; Impotence; Ion pairs; ion-pair complexation; Ion-Selective Electrodes; Membranes; Methods; Nitric oxide; pencil-fabricated graphite sensor electrode; Pharmaceutical industry; Pharmaceuticals; Polymer industry; Polymers; Potentiometric analysis; potentiometric titration; potentiometry; Selectivity; Sensors; sildenafil citrate (vitamin V); Sodium; Solvents; Sugar; Tablets; Urine; Vitamins; United States; Egypt; United States > US; Cairo Egypt; ion-pair complexation; potentiometry; pencil-fabricated graphite sensor electrode; potentiometric titration; sildenafil citrate (vitamin V)
• ISSN: 1424-8220; 1424-8220
• DOI: 10.3390/s22239128

Herein, we developed a new pencil graphite ion-selective electrode strategy for the broadly used erectile dysfunction medication, sildenafil citrate (SC, vitamin V), for its automated potentiometry and potentiometric titration profiling in marketed tablets and human urine samples. The method was based on ion-pair complexation between SC and sodium tetraphenylborate (Na-TPB) or phosphotungstic acid (PTA), embedded into a pencil-fabricated graphite sensor electrode coated with poly(vinyl chloride, PVC) matrix, which is pre-plasticized with two different pre-studied plasticizers. The modern fabricated electrodes have a proven fast near-Nernstian response for SC over the concentration range of 1.0 × 10 to 1.0 × 10 and 1.0 × 10 to 1.0 × 10 M, with LODs of 6.5 × 10 and 5.5 × 10 over a pH 3-6 for (SC-TPB)- and (SC-PTA)-based membrane sensors, of O-nitrophenyl octyl ether (O-NPOE) and dioctyl phthalate (DOP), respectively. The selectivity coefficients for different interferents, including many inorganic cations, sugars, and/or nitrogenous compounds, were tested and confirmed. Applications of the proposed method were conducted on the determination of SC in its tablets and urine samples under the proper conditions. The percent recovery values were compared with those obtained by an official method and showed an RSD ≤ 0.3% ( = 5).