Test analysis method using ion pairs of pyrocatechol azo derivatives and trihydroxyfluorones with cetylpyridinium and their chelates with metal ions immobilized on paper

A two-stage procedure is proposed for the immobilization of ion pairs of pyrocatechol azo derivatives and trihydroxyfluorones and their chelates with metal ions on paper. It is demonstrated that ion pairs of phenylfluorone and triazolylazopyrocatechol with cetylpyridinium can be used for the test determination of 0.05-20 mg/L Mo6+, and 0.1-20 mg/L W6+ and V5+ by the length of the colored zone of test strips after their contact with a test solution and for the determination of 0.01-0.5 mg/L Mo6+ by the color intensity of reactive papers after passing a test solution. The selectivity of reactions is studied, and procedures are proposed for the determination of the above ingredients in different materials. The relative standard deviation of the results of analysis is no higher than 50 %