Flow injection spectrophotometric determination of aspartame in dietary products

Abstract

A flow injection spectrophotometric method has been developed for the determination of aspartame in dietary products using ninhydrin as a colorimetric reagent. The reaction was conducted in a 1 + 1 v/v methanol–isopropanol medium also containing potassium hydroxide. The absorbance measurements were made at 603 nm. The results obtained for the determination of aspartame in table sweetener, pudding, gelatin, and refreshment (i.e., a powder dissolved in water for drinking) are in good agreement with the results obtained using a conventional manual procedure (correlation coefficient, r= 0.9984). Thirty-six results were obtained per hour, and the relative standard deviation was less than 3.5%(n= 6) for all samples. The detection limit (three times the signal blank/slope) was 3.8 × 10^–5 mol l^–1 of aspartame.