Combeau S, Chatelut M, Vittori O
Laboratoire d'Electrochimie Analytique-LICAS, Université Claude Bernard LYON I, Bât 308-ESCPE, 43 Bd du 11 Novembre 1918, 69622 Villeurbanne Cedex, France.
Talanta. 2002 Jan 4;56(1):115-22. doi: 10.1016/s0039-9140(01)00540-9.
Azorubin (E 122), Ponceau 4R (E 124) and Allura red (E 129), are the most used red dyes in soft drinks manufacturing, and in some cases two dyes are present. The aim of this work is to show that using differential pulse polarography, it was possible to distinguish these synthetic dyes from the natural dyes providing from fruits. In addition, in an appropriate supporting electrolyte, identification and quantitative analysis of these three red dyes were possible, even when they were mixed. Various electrolytes were tested such as potassium chloride, which is a classical supporting electrolyte, citric acid which is one of the components of the soft beverages, sodium citrate and a phosphate buffer. It was shown that the peak intensities and potentials, and consequently their resolution, depend greatly on the pH values. In potassium chloride and sodium citrate the peaks of Azorubin, Allura red and Ponceau 4R were well separated and dyes were identified without ambiguity. Buffer solutions with pH close to 8 and 9 appeared to be appropriate, as the potentials and the intensities of the peaks were slightly changed when small amounts of soft drinks, usually at pH close to 3, were introduced in the cell. A procedure using the standard addition technique was developed, tested with model syrups and then applied to commercial syrups, soda and non-alcoholic bitters.
偶氮玉红（E122）、丽春红4R（E124）和诱惑红（E129）是软饮料生产中最常用的红色染料，在某些情况下会同时存在两种染料。这项工作的目的是表明，使用差分脉冲极谱法，可以将这些合成染料与水果中的天然染料区分开来。此外，在合适的支持电解质中，即使这三种红色染料混合在一起，也能够对其进行鉴定和定量分析。测试了各种电解质，如经典的支持电解质氯化钾、软饮料成分之一的柠檬酸、柠檬酸钠和磷酸盐缓冲液。结果表明，峰强度和电位以及它们的分辨率在很大程度上取决于pH值。在氯化钾和柠檬酸钠中，偶氮玉红、诱惑红和丽春红4R的峰得到了很好的分离，染料的鉴定没有歧义。pH接近8和9的缓冲溶液似乎是合适的，因为当向电解池中加入少量通常pH接近3的软饮料时，峰的电位和强度会略有变化。开发了一种使用标准加入技术的方法，用模型糖浆进行测试，然后应用于商业糖浆、苏打水和无酒精苦味饮料。
