FLOW-INJECTION SPECTROPHOTOMETRIC DETERMINATION OF CYCLAMATE IN LOW-CALORIE SOFT DRINKS AND SWEETENERS

A flow injection spectrophotometric procedure is proposed for the dete rmination of cyclamate in low calorie soft drinks and sweeteners. The system is based on the reaction between nitrite and cyclamate in a med ium containing 0.1 mol l(-1) phosphoric acid; the excess of reducing a gent is determined by the Griess reaction. The flow system is designed to provide a residence time compatible with the rate of the redox pro cess. To eliminate interference caused by dye additives an alumina col umn is used. During the sampling stage, the dyes are removed and the l oop, positioned in series, becomes filled with the colourless sample s olution. After sample injection, the alumina column is regenerated by an alkaline solution flowing in the opposite direction. Cyclamate was determined in nine diet products. Some results were compared with thos e obtained by a bi-amperometric procedure (correlation coefficient, r = 0.9999, n = 4) and others were compared with label values (r = 0.996 5, n = 5). The detection limit was 3.0 x 10(-5) mol l(-1) and the rela tive standard deviation was less than 0.5% for a solution containing 8 .0 x 10(-4) mol l(-1) of cyclamate (n = 12). The proposed system allow ed us to obtain 24 results h(-1) and this was limited by the on-line a dsorption of dyes on the alumina column.