Accelerating the sample preparation for isotope ratio mass spectrometry-based determinations employing supercritical fluid chromatography

Code: 241A02MT

In sports drug testing, isotope ratio mass spectrometry is employed to enable the differentiation between endogenous and exogenous sources of urinary steroids, i.e. steroids produced inside the body or administered. Testosterone or testosterone-prohormones may be used by athlete for performance enhancement. As these steroids are endogenous, their presence alone in human urine is not suspicious. Only if urinary concentrations may exceed individual thresholds, a confirmation of the exogenous source becomes necessary and carbon isotope ratios proved to be the method of choice here.

Sample preparation protocols for isotope ratio mass spectrometry-based method are complicated and time-consuming as the purity of analytes is crucial and a prerequisite for valid isotope ratio determinations. Currently applied sample preparations encompass solid and liquid-liquid extraction steps to pre-purify and concentrate urine samples prior to the final clean-up step employing high performance liquid chromatography and fraction collection. This powerful tool for sample clean-up comes along with relatively long run-times per sample of more than 45 min and it may be necessary to use even a two-fold separation here.

This research project aims for improving this crucial step in sample preparation and shorten the run-times per sample by employing supercritical fluid chromatography coupled to a novel fraction collection tool. In supercritical fluid chromatography, pressurized carbon dioxide is used as solvent offering unique features for chromatographic separation not directly comparable to the commonly applied mixtures of water and organic solvent. Therefore, a novel sample preparation method suitable for isotope ratio mass spectrometry will be developed and validated within this project investigating the benefits of supercritical fluid chromatography in sports drug testing. To evaluate the new method and facilitate its implementation into routine doping controls, reference population-based values will be determined and compared to existing routine applications.