PHENOBARBITURATE FLOW-THROUGH ELECTRODE FOR FLOW-INJECTION ANALYSIS OF PHARMACEUTICAL PRODUCTS

We constructed, tested and applied a tubular 5-ethyl-5-phenylbarbiturate ion-selective electrode based on tetraoctylammonium 5-ethyl-5-phenylbarbiturate dissolved in o-nitrophenyl octyl ether and immobilized on poly(vinyl chloride). The intrinsic features of the proposed electrode were assessed by using a low-dispersion single-channel flow injection analysis (FIA) system for performing repeated calibrations with sodium 5-ethyl-5-phenylbarbiturate standards, whose ionic strength was adjusted to 0.1 M with 0.033 M sodium sulfate. The determination of 5-ethyl-5-phenylbarbiturate in pharmaceutical preparations was accomplished by intercalating the proposed electrode into a two-channel FIA manifold. The results obtained were compared with those provided by the British Pharmacopoeia standard method.