Single determination of α-ketoglutaric acid and pyruvic acid in beer by HPLC with UV detection

摘要

The present work describes a simple and straightforward methodology for the determination of α-ketoglutaric acid (KA) and pyruvic acid (PA) in beer. This work involves three basic steps: (a) cleaning of the sample by solid phase extraction (SPE); (b) α-ketoacids' derivatization with o-phenylenediamine (OPDA) to form quinoxalines; and (c) separation and detection of the quinoxalines by high-performance liquid chromatography with spectrophotometric detection (HPLC-UV). The identity of the eluted compounds was also confirmed by high-performance liquid chromatography-electrospray ionization tandem mass spectrometry (HPLC-ESI-MS/MS) in the positive ion mode. The developed methodology showed good repeatability (ca. 4%) and linearity as well as good limits of detection (0.091 and 0.055 mg L?1 for KA and PA, respectively) and quantification (0.30 and 0.18 mg L?1 for KA and PA, respectively). To sum up, the goal of this technical note is to develop a single HPLC procedure with previous SPE clean up suitable to use in routine analysis laboratories...