Maxis hd time of flight mass spectrometer

The identification of the mass of the molecular structures detected as peaks in the HPLC chromatograms was performed by LCMS. An excess of AmB was added to the medium (KBR-BSA 4% w/v) and after stirring for 8 h at 130 rpm [Variomag multipoint stirring plate (Thermo Electron Corporation, Germany); 15 x 6 mm magnetic stirrers (Fisherbrand, UK)] at 37°C, the undissolved drug was removed by centrifugation [3000 rpm 5 min 5°C]. The supernatant was treated for protein precipitation (section 2.4) and analysed by LCMS [Ultimate 3000 UHPLC (Dionex, USA); autosampler; quaternary pump; DAD detector; maXisHD Time-of-Flight Mass Spectrometer coupled with an electrospray source (ESI-TOF) (Bruker Daltonics, Germany)]. The conditions of the chromatography analysis were the same as previously described (section 2.3), with the exception of the injection volume being 30 μL and a split flow post column before the mass spectrometry detector to a flow rate of 0.3 mL/min. In this case, the formate buffer (50 mM) was prepared with formic acid and ammonium formate, in order to make it suitable for Mass Spectrometry (absence of sodium ions). The samples were analysed in negative mode. Data was processed using external calibration with the Bruker Daltonics software (DataAnalysisTM) as part of the overall hardware control software (CompassTM).