Method for the Analysis of Inorganic and Organic Acid Anions in All Phases of Beer Production Using Gradient Ion Chromatography. Stephanie Boyles, Analytical Laboratory, Coors Brewing Company, BC600, Golden, CO 80401. J. Am. Soc. Brew. Chem. 50:0061, 1992.

An accurate analytical method has been developed to separate and quantify nine organic acids (acetate, lactate, formate, pyruvate, succinate, malate, maleate, oxalate, and citrate) and six inorganic anions (fluoride, chloride, bromide, nitrate, sulfate, and phosphate) in all phases of beer production, from wort to the final package. The organic acids and inorganic anions were separated in a 43-min chromatographic run. This method uses gradient ion chromatographic separation using the Dionex Omni-Pac PAX-500 column with suppressed conductivity detection. Possible interferences, such as coelution of analytes and matrix effects in the beer, were resolved and verified. The quantitative measurement of anions in beer products has not been previously available by isocratic ion chromatographic methodology. With gradient ion chromatography, the inorganic anions in beer can be accurately separated and quantified without the problem of interferences with organic acids. The linearity, precision, and percent recovery of the method throughout all phases of beer production also were determined. Sample treatment requires a dilution with Milli-Q water followed by a C₁₈ Sep-Pak cleanup and filtration through a 0.45-µm nylon filter. This method provides an accurate, quantitative, and simultaneous measurement of inorganic anions and organic acids in beer products.

Keywords: Gradient ion chromatography, Inorganic anions, Organic acids