The Use of Post-Column Dynamic Ion-Pair Extraction for the Hplc Detection of Anionic Additives in Foods

Abstract

Applications of post-column ion-pair extraction with absorbance detection to the determination of anionic food additives are discussed. The compounds studied include sodium dioctylsulfosuccinate, artificial sweeteners and free fatty acids. Dyes such as methylene blue and crystal violet provide different extraction and detector wavelength selectivities when used as counter ions. Mobile phase composition, dye concentration; phase ratios and extraction system design influence the sensitivity of the system. Excellent selectivity is shown through application of the approach to a variety of food samples including drink powders, carbonated beverages and juices. Free fatty acids can be determined directly without derivatization at low parts per million levels in samples such as orange juice, margarine and butter using a mobile phase of up to 99% acetonitrile. Absolute detection limits for the additives studied are in the low nanogram range.