Analytical Sciences

Abstract − Analytical Sciences, 20(10), 1437 (2004).

Flow-through Spectrophotometric Sensor for the Determination of Aspartame in Low-Calorie and Dietary Products
L. F. CAPITÁN-VALLVEY, M. C. VALENCIA, and E. Arana NICOLÁS
Department of Analytical Chemistry, Research Group Solid Phase Spectrometry, Faculty of Sciences, University of Granada, Avda, Fuentenueva s/n, E-18071 Granada, Spain
A very simple flow-through sensor is presented for the determination of the intense sweetener aspartame in low-calorie and dietary products. The sensor is implemented in a monochannel flow-injection system with UV spectrophotometric detection using a Sephadex CM-C25 cationic exchanger packed 20 mm high in a flow cell. This method is based on the transient retention of a cationic species of the sweetener on the solid phase when a pH 5.0 acetic acid sodium acetate buffer (0.01 M) is used as a carrier (2.6 mL-1 min). The carrier itself elutes the analyte from the solid support, regenerating a sensing zone. Aspartame was determined by measuring its intrinsic absorbance at 219 nm at its residence time without any derivatization. Calibration graphs were linear over the range of 5.0 - 600.0 µg mL-1 with an RSD of 0.55% (peak height). This sweetener was determined in several samples by measuring the height or peak area, obtaining recoveries ranging between 95 - 101% and 97.5 - 101%, respectively. The procedure was validated for its use in the determination of aspartame in low-calorie and dietary products, giving reproducible and accurate results.