Simultaneous Determination of Benzoic Acid and Sorbic Acid in Food Products by CE after On-line Preconcentration by Dynamic pH Junction

• Published in: Chromatographia 2011-06, Vol.73 (11-12), p.1217-1221
• Main Authors: Zhang, Xinfeng, Xu, Shuxia, Sun, Yonghua, Wang, Yanyan, Wang, Cheng
• Format: Article
• Language: English
• Subjects: Analytical Chemistry; Biological and medical sciences; Chemistry; Chemistry and Materials Science; Chromatography; Food industries; Full Short Communication; Fundamental and applied biological sciences. Psychology; General aspects; Laboratory Medicine; Methods of analysis, processing and quality control, regulation, standards; Pharmacy; Proteomics
• ISSN: 0009-5893; 1612-1112
• DOI: 10.1007/s10337-011-2009-3

An online dynamic pH junction method has been proposed for sensitive determination of benzoic acid (BA) and sorbic acid (SA) by capillary electrophoresis (CE). It was based on the decreased mobility of the analytes when they migrated from sample zone with low pH to background electrolytes with high pH. Under optimized conditions, the limits of detection (S/N = 3) of BA and SA were 0.03 and 0.02 mg L −1 , respectively. According to the permitted limits of BA and SA in food (GB2760), the samples can be diluted about 2,000–20,000-folds to estimate whether the contents of BA and SA are in the safety range. Beverage, vinegar and fruit jam samples were analyzed after simple dilution, and the results were satisfactory with the recoveries in the range of 91–108%. The whole analysis process needs about only 10 min, which is much faster than the method of liquid–liquid extraction followed by CE determination.