Lipopeptide biomarker profiles were determined by using matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) using the method of Price et al. (2007) as follows. MALDI-TOF mass spectra were acquired on a Bruker-Daltonic Omniflex instrument operating in reflecton mode. Ion source 1 was set to 19.0 kV and source 2 to 14.0 kV, with lens and reflector voltages of 9.20 and 20.00 kV, respectively. Aqueous samples were co-crystallized with 2,5-dihydrobenzoic acid matrix (10 mg ml21 in acetonitrile) on a Bruker-Daltonics 49-place target. The laser output was at 337.1 nm, typically at 60 % of 150 ́ıJ maximum output, and 80 shots were accumulated. A 200 ns pulsed ion extraction was used with matrix suppression up to 200 Da. The instrument was calibrated externally on a dp series of malto-oligosaccharides.