Organic acid profiles in fruit juices are important in the beverage industry to characterize flavor, maintain product quality, and to meet labeling requirements. To analyze organic acids and anions of strong acids, such as chloride and sulfate, which are also present in beverages, ion chromatography with suppressed conductivity is the ideal analytical method. Unlike the anions of strong acids which are fully ionized, organic acids are weakly ionized and can exhibit lower conductivity responses versus concentration than the strongly ionized anions. The new Thermo Scientific Dionex QD Charge Detector promotes complete disassociation of many weakly disassociated compounds by drawing a current at a fixed potential. As a result, the charge responses of singly-charged organic acids and doubly-charged and triply-charged organic acids are proportionally higher than conductivity.Here we demonstrate separations of organic acids on a 4-�m particle size, capillary anion-exchange column. Four �m particle columns produce higher signal to noise with more efficient separations but also have higher system backpressure, and therefore can only be used on a high-pressure capillary IC system. Capillary IC at �L/min flow rates is always on and ready for analysis and requires only 5.2 L/yr of deionized water. The results show comparably higher QD response for organic acids compared to chloride and sulfate. Additionally, use of CD/QD ratios to assess peak purity is demonstrated, thereby improving reporting accuracy.

Determinations of inorganic anions and organic acids in beverages using suppressed conductivity and charge detection

247th National Meeting (2014)

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.