The Fluorometric Determination of Cyclamate using 1, 2-Naphthoquinone-4-sulfonic Acid. II

Abstract

Fluorometric determination of cyclohexylamine with 1, 2-naphthoquinone-4-sulfonic acid was applied to the determination of cyclamate in various foods. Cyclamate was hydrolyzed to cyclohexylamine as follows : To 1 ml of a sample solution containing 50-500μg of cyclamate, 0.5 ml of 0.5N sulfuric acid solution and 3 ml of dimethyl sulfoxide were added, heated for 2 hr in a boiling water bath, cooled, and diluted to 25 ml with water. Cyclohexylamine in the solution was estimated by the procedure described in the preceding paper. In the recovery test of cyclamate in various foods, the recovery was satisfactory. Determination of cyclohexylamine in human urine by the fluorometric method with 1, 2-naphthoquinone-4-sulfonic acid was also investigated. Cyclohexylamine was extracted with chloroform from urine basified with 2N sodium hydroxide. The reaction solution of cyclohexylamine and 1, 2-naphthoquinone-4-sulfonic acid was shaken with dichloromethane. The concentrated dichloromethane layer was spotted on a silicagel plate and developed with a mixture of ether : chloroform (1 : 2). Extract of the orange-yellow spot with borate buffer (pH 10.3) was treated with sodium borohydride, and acidified with 0.2 N sulfuric acid solution. The developed fluorescence was estimated. The recovery ratio was 94.3%.