ANALYST, 1990, VOL.115, PP. 309-313

Automated Flow Injection Spectrophotometric Determination of para- and meta-Substituted Phenols of Pharmaceutical Interest Based on Their Oxidative Condensation With 1-Nitroso-2-naphthol

Constantinos A. Georgiou and Michael A. Koupparis*
Laboratory of Analytical Chemistry, Department of Chemistry, University of Athens, 104 Solonos Street, Athens 106 80, Greece


The reaction of para- and meta-substituted phenols with 1-nitroso-2-naphthol in the presence of either CeIV or PbIV as an oxidant has been used to develop a fast automated flow injection (FI) method. A stopped-flow kinetic study of the reaction revealed the optimum conditions for the proposed FI method. Acetaminophen, amoxicillin, cefadroxil, isoxsuprine, nylidrin, propylparaben, tyrosine and metaraminol can be determined in the range 1 x 10-4- 8 x 10-4 M, with relative standard deviations of <2%, and a measurement throughput of 40 measurements h-1. The method was evaluated by performing interference studies of common excipients and assaying commercial formulations of acetaminophen and isoxsuprine. The results were in good agreement with those obtained by acceptable spectrophotometric or high-performance liquid chromatographic methods (mean difference 2.1%). The high sample throughput of the FI method was exploited by performing a content uniformity test of isoxsuprine tablets.


Keywords: Flow injection; 1-nitroso-2-naphthol; acetaminophen; isoxsuprine; phenolic drug determination

*Corresponding author.
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Questions and comments to author: Dr C.A. Georgiou, cag@aua.gr
Phone: +3010-5294248, fax: +3010-5294265
Chemistry Laboratory, Agricultural University of Athens, Greece