Flow-injection spectrophotometric determination of cyclamate in sweetener products with sodium 1,2-naphthoquinone-4 sulfonate

A method for the determination of cyclamate in sweetener tablets is proposed. The method is based on the conversion of cyclamate to cyclohexylamine and the subsequent reaction with 1,2-naphthoquinone-4-sulfonate, yielding a spectrophotometrically active derivative which is detected at 480 nm. The hydrolysis step is performed batch wise by treatment of cyclamate with hydrogen peroxide and hydrochloric acid, while the cyclohexylamine derivatization is carried out in a flow-injection system. Conditions for both hydrolysis and derivatization have been optimised. The Linear range is up to 10(-3) M cyclamate, the overall repeatability 3.1% and the detection limit is 7.7 x 10(-6) M. The accuracy of the method proposed in the analysis of commercial sweetener tablets is about 3.5%. (C) 1999 Elsevier Science B.V. All rights reserved.