Automated determination of salts in water-soluble certifiable color additives by ion chromatography.

A previously developed ion chromatographic method for the determination of salts in water-soluble certifiable color additives was automated, using a Model 12 Dionex ion chromatograph equipped with a program controller and programmable computing integrator. Programs were written for the program controller for continuous automated analysis of up to 59 samples in about 20 h, with periodic regeneration of the suppressor column and automatic shut-down. All data were processed through the integrator, programmed to give results in weight/weight percent. Recoveries were performed on 4 anions: chloride, phosphate, bromide, and sulfate. Twenty-five color additives could be analyzed by the method. Standard deviations in the determinations ranged from 0.01 to 0.16 at addition levels of 0.20-9.45% with 6 replications. Recoveries for addition levels of 0.2-5.0% with 2 replications fell within the range of 84.0-105.0%. Approximate lower limits of detection for each anion were as follows: chloride, 0.07%; phosphate, 0.10%; bromide, 0.06%; sulfate, 0.07%.