Determination of Isohumulone and Isocohumulone in Beer by HPLC. James T. Whitt and Janet Cuzner, Jos. Schlitz Brewing Co., Milwaukee, WI 53201. J. Am. Soc. Brew. Chem. 37:0041, 1979.

A high-pressure liquid chromatographic (HPLC) method is described for separating and measuring isohumulone and isocohumulone in beer. A trimethylpentane extract is dried and resuspended in methanol containing an internal standard. Paired-ion chromatography is achieved by adding to the mobile phase a large organic counter-ion that complexes with the oppositely charged ionic species, the iso-α-acids. The complexes are then chromatographed as non-ionic species on a reverse-phase column. Ion-exchange chromatography is used to calibrate the method. Wort, beer, and beer fractions were analyzed to demonstrate the method's application.

Keywords: Beer, High-pressure liquid chromatography, Iso-α-acids, Isocohumulone, Isohumulone