Determination of Chlorides and Sulfates in Food Colors by Ion Chromatography

Abstract

A non-suppressed ion chromatographic (IC) method with monitoring of conductivity is described for the determination of soluble chlorides and sulfates in food colors and their aluminum lakes (Al-L).Each color dissolved in water was ion-chromatographed directly with eluent containing phthalic acid (2.5mM) and tris (hydroxymethyl) aminomethane (2.4mM). The recoveries of sodium chloride (0.474μg) and sodium salfate (0.562μg) added to food color standards (each 20μg) were in the range of 98.4-103.2% and 100.5-103.7%, respectively.The solution of soluble chlorides and sulfates from each food color Al-L was prepared by a modification of the standard procedure specified in the Japanese Standards of Food Additives 5th ed. (JSFA-V) and applied to IC under the same conditions as used for food colors. The recoveries of sodium chloride (0.292mg) and sodium salfate (0.296mg) added to commercially available food color Al-L (50mg) were in the range of 86.0-96.3% and 71.0-88.2%, respectively.Compared with the standard method specified in JSFA-V, the IC method showed smaller standard deviations and better recoveries. In addition, the IC method is a simple and simultaneous analysis for soluble chlorides and sulfates. Therefore, it appears that the IC method is suitable as a substitute for the standard method, which is time-consuming and requires considerable care in the analysis.