University of North Florida
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Stuart Chalk, Ph.D.
Department of Chemistry
University of North Florida
Phone: 1-904-620-1938
Fax: 1-904-620-3535
Website: @unf

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Classification: Food -> dessert -> pudding

Citations 1

"Flow Injection Spectrophotometric Determination Of Aspartame In Dietary Products"
Analyst 1994 Volume 119, Issue 9 Pages 2101-2104
Joaquim de Araújo Nóbrega, Orlando Fatibello-Filho and Iolanda da Cruz Vieira

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 x 10^-5 mol L-1 of aspartame. Sample (0.2-0.6 g) was stirred with 10 mL of methanol/propan-2-ol (1:1; solvent A) for 2 min. The suspension was filtered and the filtrate was diluted to 25 mL with solvent A. A portion of the solution was injected into a carrier stream (2.5 ml/min) of solvent A and subsequently merged with streams (both 0.3 ml/min) of 0.293 M KOH and 0.037 M ninhydrin (both in solvent A). The mixture was transported to a helical reaction coil (2 m x 0.8 mm i.d.) immersed in a water-bath kept at 60°C. The solution then passed through a de-bubbler after which the absorbance was measured at 603 nm. A diagram of the manifold used is given. The calibration graph was linear from 0.34-2.4 mM aspartame, the detection limit was 38 µM and the RSD (n = 6) was 3.5%. Recoveries were quantitative and the throughput was 36 samples/h. The method was applied to several dietary products, viz., table sweetener, pudding, gelatin and refreshment powder.
Aspartame Spectrophotometry Heated reaction