Tandem time-of-flight mass spectrometer with improved mass resolution

A method for improving mass resolution in tandem time-of-flight mass spectrometers, the method comprising:

• a) generating a pulse of ions from a sample of interest;
• b) selecting ions from the pulse of ions that are substantially within a predetermined mass-to-charge ratio range and rejecting substantially all other ions;
• c) fragmenting a fraction of the selected ions;
• and
• d) exposing the selected ions and fragments thereof to a time varying bias that adds energy to the fragments which at least partially compensates for energy lost due to fragmentation;
• and
• e) analyzing the selected ions and fragments thereof by time of flight mass spectrometry.

A tandem time-of-flight mass spectrometer comprising:

• a) a pulsed source of ions that focuses a packet of ions substantially within a predetermined mass-to-charge ratio range onto a focal plane in a flight path of the packet of ions;
• b) an ion selector positioned substantially at the focal plane that receives the focused packet of ions, wherein the ion selector selects ions substantially within the predetermined mass-to-charge ratio range and rejects substantially all other ions;
• c) an ion fragmentor positioned in the flight path of the selected ions, the ion fragmentor fragmenting a fraction of the selected ions;
• d) a first drift space positioned in a flight path of the selected ions and fragments thereof that facilitates fragmentation;
• e) a pulsed ion accelerator positioned in a flight path of the selected ions and fragments thereof after the first drift space, wherein the pulsed ion accelerator accelerates the selected ions and fragments thereof;
• f) a conducting tube positioned in the flight path of the selected ions and fragments thereof after the pulse ion accelerator, the conducting tube being biased with a time varying bias voltage that increases the energy of the fragments relative to the selected ions;
• and
• g) an ion detector that detects the selected ions and fragments thereof.

A tandem time-of-flight mass spectrometer comprising:

• a) a pulsed source of ions that focuses a packet of ions substantially within a predetermined mass-to-charge ratio range onto a focal plane in a flight path of the ions;
• b) an ion selector that receives the focused packet of ions, wherein the ion selector selects ions substantially within the predetermined mass-to-charge ratio range and rejects substantially all other ions;
• c) an ion fragmentor positioned in the flight path of the selected ions, the ion fragmentor fragmenting a fraction of the selected ions;
• d) a pulsed ion accelerator positioned in a flight path of the selected ions and fragments thereof after the ion fragmentor, wherein the pulsed ion accelerator accelerates the selected ions and fragments thereof;
• and
• e) an electrode positioned in the flight path of the accelerated selected ions and fragments thereof after the pulsed ion accelerator, the electrode being biased with a time varying bias voltage that increases the kinetic energy of the fragments relative to the selected ions.

A tandem time-of-flight mass spectrometer comprising:

• a) a pulsed source of ions that focuses a packet of ions substantially within a predetermined mass-to-charge ratio range onto a focal plane in a flight path of the ions;
• b) an ion fragmentor that receives the focused packet of ions, the ion fragmentor fragmenting a fraction of the ions;
• c) an ion selector positioned in the flight path of the fragmented ions, wherein the ion selector selects fragmented ions substantially within the predetermined mass-to-charge ratio range and rejects substantially all other ions and ion fragments;
• d) a pulsed ion accelerator positioned in a flight path of the selected ions and fragments thereof after the ion fragmentor, wherein the pulsed ion accelerator accelerates the selected ions and fragments thereof;
• and
• e) an electrode positioned in the flight path of the accelerated selected ions and fragments thereof after the pulsed ion accelerator, the electrode being biased with a time varying bias voltage that increases the kinetic energy of the fragments relative to the selected ions.