Caffeine and its major metabolites; Theobromine, Theophylline and Paraxanthine are routinely monitored by anti-doping agencies as potential performance enhancers. Similar precursors and product ions of Theophylline and Paraxanthine makes the LCMS analysis of this panel very challenging. The aim of the study was to develop an efficient extraction and analysis method for caffeine and metabolites in race horse urine samples.
Optimization of Solid Phase Extraction procedure was carried out to achieve clean extracts with high recoveries. Samples were prepared at pH 6.0 prior to loading onto the CSDAU503 SPE columns (Clean Screen® DAU 500 mg, 3mL). Hydrolysis step during sample preparation was eliminated as the results were found to be comparable to unhydrolyzed samples. Extracts were derivatized with MSTFA-1% TMCS followed by analysis on a 13 min long GCMS method.
The DAU sorbent not only produced excellent peak shapes and absorbance values, but it also allowed the samples to be prepared at pH 6.0 which is favorable for urine dilution. These advantages made CSDAU plate the preferred choice for this study over other options. For the very first time, Caffeine and its major metabolites were simultaneously analyzed on GCMS. This screening and confirmatory method was validated as per the parameters specified in the European Commission’s Decision (2002/657/EC).
Citation: Göktaş, Eylem Funda, et al. “Simultaneous quantification of caffeine and its main metabolites by gas chromatography mass spectrometry in horse urine.” Biomedical Chromatography (2022): e5445.