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Identifying Molecules by Mass Spectrometry

The need to identify complex molecules in real-world samples has propelled mass spectrometry into a $3 billion industry, growing 8% annually. The fragmentation of molecules within a mass spectrometer is necessary to accurately reveal their identity. The current approach (called CID for collision-induced dissociation) uses a sledgehammer that complicates identification by producing complex patterns with considerable noise.

Our technology use low-energy electrons as a scalpel to cut molecules with precision. We can switch between three complementary methods of fragmentation in milliseconds to provide multiple sets of fingerprints to correctly identify molecules as large as whole proteins. These methods are well established, but have been restricted to expensive research instruments because of the difficulty of confining enough low-energy electrons in small volumes necessary for efficient fragmentation. We have solved this limitation by sculpting magnetic fields to confine electrons in a hockey puck-sized device that can be retrofitted into current mass spectrometers with minimal re-engineering.

The illustration above shows how a magnetic field can be used to force electrons emitted from a hot filament to converge on the flight path of molecular ions and fragment them in microseconds.  The energy of the electrons can be rapidly increased to induce greater fragmentation of both small molecules recalicatrant to CID and larger molecules such as peptides and proteins.   

Here is one version of the ECD cell that we have installed in a Bruker Q-ToF.  The cell is mounted between the first Quad that the cooling chamber preceeding the ToF.  The ions enter through the small hole in the center of the cell and ECD fragments exit from the back.  The wires are electrical leads that provide power for the electron-emitting filament and electrostatic lenses.