Thermo Scientific Q Exactive Plus Orbitrap Mass Spectrometer
The LC system includes a ThermoFisher Vanquish Binary Pump with settable flow rates of 0.001-5 mL/min, an integrated vacuum degasser and automated purge unit. The column compartment is temperature regulated. The LC system also includes a refrigerated autosampler suitable for vials or 96-well plates. It has a split-loop sampler that can accurately draw volumes of 0.010-100 μL. The LC system can withstand pressures up to 1517 bar and is suitable for high-speed and high-resolution applications.
The MS is a ThermoFisher Q Exactive Plus quadrupole orbitrap mass spectrometer with a HESI II probe capable of operating in a rapid polarity switching mode. We also have an APCI probe that can be swapped in as the source. The MS contains a mass filter in front of a curved ion trap, allowing for MS-MS (fragmentation) and select ion monitoring (SIM) detection. The system can also operate in full scan mode. The scan rate can be as high as 140,000 (1.5 Hz) and the mass accuracy is > 1 ppm upon calibration.
Chromatographic Capabilities
To enable the detection of a broad range of classes of small molecules, chromatographic methods were developed to optimally separate highly polar (pHILIC), moderately polar (amide), and non-polar (PFP & C18) molecules. Libraries of small molecules have been run on each chromatographic method to allow targeted analysis of up to 600 small molecules in each run. Given the high mass accuracy, untargeted analysis and stable isotope tracing experiments can also be performed using this instrument.
Data Analysis
Software for targeted and untargeted analysis are available for use. Training is available to anyone in the UMass Chan community who is interested. Email jessica.spinelli@umassmed.edu for details. The data analysis software include TraceFinder 5.1 (ThermoFisher), XCalibur (ThermoFisher), Compound Discoverer (ThermoFisher), and El Maven.
Optimal Uses
This system is optimally used for the detection of small molecules such as metabolites. In a single injection, a sample can be analyzed with high sensitivity (picomolar concentrations) and high resolution (distinction of mass shifts caused by 13C and 15N isotopes) for all small molecules that fall within the range of the full scan settings selected. Given the high resolution, this workflow is often used for stable isotope tracing experiments and untargeted metabolite profiling.