Analysis of the enol–keto tautomers of indole-3-pyruvic acid

Indole-3-pyruvic acid (IPyA) is an important naturally occurring biosynthetic intermediate whose quantitation by standard analytic techniques can be complicated as it can exist as either the keto or enol tautomer. Here, we present a detailed analysis of the tautomerism of IPyA and provide further evidence that the two tautomers of IPyA may be readily separated by ultra high-performance liquid chromatography and that the relative proportions of each form may be controlled using temperature and pH.