The measurement of organic acids, in all phases of beer
production, can be used to help track metabolic products
of fermentation and to correlate beer flavor trends. One
way to separate organic acids is with ion-exclusion
chromatography using suppressed conductivity detection.
The Dionex IonPac ICE-AS6 column is an ion-exclusion
column designed for the efficient separation of low
molecular weight aliphatic organic acids including
hydroxy-substituted organic acids, in addition to species
such as aliphatic alcohols and glycols. Using this separation
mechanism, weakly ionized species are separated based on
differences in their pKas. Strong inorganic acid anions are
not retained by the stationary phase and elute in the void
volume of the column. The standard eluent for use with
the Dionex IonPac ICE-AS6 column is 0.4 mM heptafluorobutyric
acid (perfluorobutyric acid). Other monoprotic
acids can be used; however, the background conductivity
will be higher. The experimental conditions are listed in
Figure 6.