Sixteen cheese-related organic acids were analysed by an ion-exchange HPLC
protocol developed in this study. The proposed technique was compared to a
typical reverse-phase separation of the same organic acid mixture to establ
ish the most satisfactory HPLC methodology. The ion-exchange method yielded
best results for the concentration of compounds analysed, resolution, dura
tion of separation and ease of analysis. A number of compounds co-eluted wi
th the proposed ion-exchange HPLC protocol but could be individually distin
guished and quantified using spectral array UV detection and three-dimensio
nal Spectacle software. Isoplot graphs were found to be valuable for the mo
re detailed analysis of HPLC chromatograms. The reverse-phase method succee
ded in eluting all the polar and more non-polar organic acids in a single c
hromatographic run with the aid of a buffer-methanol gradient. However, res
olution was not as good as with the ion-exchange method. The reverse-phase
methodology was found to be more laborious, requiring column re-equilibrati
on and longer run time, and could not accomplish analysis of diacetyl. (C)
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