Sample preparation in centrifugal microfluidic discs for human serum metabolite analysis by surface assisted laser desorption/ionization mass spectrometry

We introduce a centrifugal microfluidic disc that accepts a small volume in (~5 µL), performs sample clean-up on human serum samples, and delivers a small volume out, for subsequent metabolite analysis by surface assisted laser desorption/ionization (SALDI) mass spectrometry (MS) or hydrophilic interaction liquid chromatography (HILIC) MS. The centrifugal microfluidic disc improves the MS results by removing proteins and lipids from serum. In the case of SALDI-MS, sample background electrolytes are segregated from analytes during the spotting process by the action of the SALDI-chip during drying, for further clean-up, while HILIC separates the salts in HILIC-MS. The resulting mass spectra of disc-prepared samples shows a clean background and high signal to noise ratio for metabolite peaks. Several representative ionic metabolites from human serum samples were successfully quantified. The performance of the sample preparation disc for SALDI-MS and HILIC-MS were assessed and were comparable. Reproducibility...