Analysis of Soft Drinks:: UV Spectrophotometry, Liquid Chromatography, and Capillary Electrophoresis
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[1] University of Florida
University of Florida
Estados Unidos
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- Localización: Journal of chemical education, ISSN 0021-9584, Vol. 75, Nº 5 (May), 1998, págs. 625-629
- Idioma: inglés
- Texto completo no disponible (Saber más ...)
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Resumen
Instrumental analysis students analyze commercial soft drinks in three successive laboratory experiments. First, UV multicomponent analysis is used to determine caffeine and benzoic acid in Mello YelloTM using the spectrophotometer's software and manually by the simultaneous equations method. The following week, caffeine, benzoic acid and aspartame are determined in a variety of soft drinks by reversed-phase liquid chromatography using 45% methanol/55% aqueous phosphate, pH 3.0, as the mobile phase. In the third experiment, the same samples are analyzed by capillary electrophoresis using a pH 9.4 borate buffer. Students also determine the minimum detection limits for all three compounds by both LC and CE. The experiments demonstrate the analytical use and limitations of the three instruments. The reports and prelab quizzes also stress the importance of the chemistry of the three compounds, especially the relationships of acid/base behavior and polarity to the LC and CE separations.
