摘要：Fluorometric method with 1, 2-naphthoquinone-4-sulfonic acid for the determination of cyclohexylamine, a hydrolysation product of cyclamate, was investigated. Optimal conditions for the determination was as follows : A sample solution of cyclohexylamine and 1, 2-naphthoquinone-4-sulfonic acid was heated at 50°for 10 min in the presence of borate buffer (pH 10.3). The reaction solution was shaken with dichloromethane, and the organic layer was dried over anhyd. sodium sulfate and then treated with sodium borohydride. Ethanolic sulfuric acid solution was added to the reduced solution. The developed fluorescence was determined at 397 nm, exciting at 345 nm. This fluorometric method was applied to the determination of cyclohexylamine in the hydrolytic solution of cyclamate by the reported procedure of Johnson, et al., and a satisfactory result was obtained. In this case, coexistence of food additive did not interfere with the determination. Coloured substance, 4-cyclohexylamino-1, 2-naphthoquinone (I) was obtained from the reaction solution of cyclohexylamine and 1, 2-naphthoquinone-4-sulfonic acid. Intense violet fluorescence was observed in the dichloromethane solution of I by reduction with sodium borohydride and then addition of ethanolic sulfuric acid solution.
