Tandem quadrupole mass spectrometer for selected ion fragmentation studies and low energy collision induced dissociator therefor

A selected ion mass spectrometer for the analysis of unknown samples comprising:

• a source capable of ionizing unknown sample molecules of widely varying molecular weights to produce molecular ions, fragment ions, and/or other ions derived from the sample components;
• first and second analyzers in tandem;
• means for directing unknown ionized sample molecules, fragments or otherwise derived ions of sample components from said source into said first mass analyzer;
• a low-energy collision-induced dissociation fragmentation/reaction stage interposed between said mass analyzers for receiving selected ionized sample molecules, fragments or components from said first mass analyzer, for fragmenting or reacting the selected ionized sample molecules, fragments or derivatives into ionized further fragments or products, for collecting the ionized further fragments or products, and for directing the ionized further fragments or products into said second mass analyzer, said fragmentation/reaction stage including a collision gas-containing electrodynamic focus device;
• and
• a detector responsive to the output of said second mass analyzer.

A quadrupole-based selected ion mass spectrometer for the analysis of unknown samples comprising, in series:

• a source capable of ionizing unknown sample molecules of widely varying molecular weights to produce molecular ions, fragment ions, and/or other ions derived from the sample components;
• a first quadrupole-type mass analyzer capable of scanning and selecting ionized sample molecules, fragments or derivatives of particular mass over a range of atomic mass units;
• a low-energy collision-induced dissociation fragmentation/reaction stage including an electrodynamic focus device, with a collision gas introduced into said electrodynamic focus device, said low-energy fragmentation/reaction stage arranged to receive the selected ionized sample molecules, fragments or derivatives from said first quadrupole-type mass analyzer, and producing ionized further fragments or products of the selected ionized sample molecules, fragments, or derivatives;
• a second quadrupole-type mass analyzer capable of scanning over a range of atomic mass units for selecting ionized further fragments or products of particular mass;
• and
• a detector at the output of said second quadrupole-type mass analyzer;
• whereby the output of said detector may be examined as said first and/or second mass analyzers are scanned to produce a representation of a mass spectrum for identifying the unknown sample and/or components thereof.

A tandem quadrupole mass spectrometer for selected ion fragmentation studies to analyze unknown samples, comprising:

• first, second and third quadrupole-type devices arranged in tandem;
• means for operating said first and third quadrupole-type devices in a scanning mass analysis mode over a range of atomic mass units;
• means for operating said second quadrupole-type device in a broad-band filter mode;
• means for introducing a collision gas into said second quadrupole-type device;
• a source capable of ionizing unknown sample molecules of widely varying molecular weights to produce molecular ions, fragment ions, and/or other ions derived from the sample components;
• means for injecting molecular ions produced by said source into said first quadrupole-type device at relatively low ion axial kinetic energies;
• and
• means for detecting the output of said third quadrupole-type device

An efficient arrangement for fragmenting molecular ions by collision-induced dissociation and collecting the resultant fragments, said arrangement comprising:

• an electrodynamic focus device;
• a collision gas introduced into said electrodynamic focus device;
• and
• means for injecting molecular ions at relatively low ion kinetic energies into one end of said electrodynamic focus device;
• fragments or reaction products of the injected molecular ions being produced as a result of collisions with the atoms or molecules of said collision gas, being confined radially within said electrodynamic focus device, and exiting from the other end of said electrodynamic focus device, the collision gas being specifically chosen to enhance particular features of the fragmentation and/or reaction process.

A method for analyzing unknown samples by tandem mass spectroscopy, comprising the steps of:

• (1) ionizing a quantity of unknown sample to produce molecular ions, fragment ions and/or other ions derived from sample components;
• (2) mass scanning the molecular ions, fragment ions and/or derivative ions to select ions of various particular molecular weights at different times during a mass scan;
• (3) directing ions selected in step (2) at relatively low ion kinetic energies into an electrodynamic focus device having a collision gas introduced therein, fragment or product ions being produced as a result of collisions between the selected ions and the collision gas atoms or molecules;
• (4) mass scanning the fragment or product ions produced in step (3) for each of the various particular weights selected during the step (2) mass scan;
• and
• (5) detecting the ions selected in step (4) to produce a representation of a mass spectrum for comparison with reference spectra to identify an unknown sample and/or components thereof.