Tetracycline-selective electrode for content determination and dissolution studies of pharmaceuticals by flow-injection analysis (FIA)

✍ Scribed by M. Goreti F. Sales; M. Conceição B. S. M. Montenegro

• Publisher: John Wiley and Sons
• Year: 2001
• Tongue: English
• Weight: 170 KB
• Volume: 90
• Category: Article
• ISSN: 0022-3549
• DOI: 10.1002/jps.1066

✦ Synopsis

The present work describes the construction and evaluation of different tetracycline (TC)-selective electrodes without inner reference solution and with polymer membranes. The several electrodes were prepared with poly(vinyl chloride) or ethylene(vinyl acetate) membranes comprising o-nitrophenyl octyl ether or bis(2ethylhexyl)sebacate as mediator solvents and tetracycline tetrakis(4-clorophenyl)borate as ion exchanger. The best performance was recorded for the poly(vinyl chloride) membranes with bis(2-ethylhexyl)sebacate. Using solutions with adjusted ionic strength, this type of electrode presented a slope of 57.4 mV decade À1 and a reproducibility of AE0.3 mV day À1 , for an analytical range from 1.2 Â 10 À4 to 1.0 Â 10 À2 M. The pH working range was 2.0±3.8. Tubular-shaped potentiometric detectors based on the same selective membrane were also constructed. When TC solutions with adjusted ionic strength of concentrations ranging from 1.0 Â 10 À4 to 1.0 Â 10 À2 M were injected into a single-channel ¯ow manifold, the detectors presented a slope of 56.6 mV decade À1 and a reproducibility of AE0.5 mV day À1 . The pH working range was 1.9±3.9. Both batch and ¯ow procedures were applied to the potentiometric analysis of oral dosage forms. Average recoveries were within 98.6 to 100.3% and the t test indicated the accuracy of these results in comparison to an independent methodology. The ¯ow system with the potentiometric detector was employed in dissolution studies as well.