Figure 6 shows the simultaneous separation of a mixture
of inorganic and organic anions in an American ale using
the Dionex IonPac AS11 column. The sample was
degassed and diluted 1:40 prior to injection. The sodium
hydroxide concentration in Eluent 2 is weak enough that
not only is fluoride eluted after the void, but several
weakly retained monovalent organic acids are also
resolved. The addition of methanol to the eluent modifies
the selectivity of the column for the more hydrophobic
anions, thus allowing resolution between succinate and
malate and also between tartrate and maleate, which
often added to municipal water supplies to prevent tooth
decay and is harmless for brewing purposes. Chloride is
eluted next, and at levels above 250 mg/L it has been
found to enhance the sweetness of beer. However, it may
also hamper yeast flocculation. Nitrate was once thought
of as a problem in the brewing process, but it has since
been discovered that it is the nitrite produced from nitrate
that affects yeast metabolism to cause weak and incomplete
fermentation. Sulfate is found naturally in water but imparts
a sharp, dry edge to well hopped beers and is therefore
kept to a minimum. Finally, phosphate is present in the
malt and buffers the mash at a slightly acidic pH.