US 5,479,012 A · Method of space charge control in an ion trap mass spectrometer

Abstract

A method of using a quadrupole ion trap mass spectrometer for high resolution mass spectroscopy is disclose. In the preferred embodiment, the space charge in the ion trap is controlled with high accuracy. The mass spectrum to be analyzed is divided into a plurality of contiguous mass segments and each of the segments is separately scanned. To control space charge, a broadband supplemental waveform is applied to the ion trap during the ionization period for each segment, the broadband signal being construct to eliminate all unwanted ions from the ion trap by resonance ejection such that only those ions having masses within the desired mass segment remain in the ion trap. Preferably, the ionization of each mass segment is performed under identical trapping conditions, and the ionization parameters for each segment is adjusted to optimize the space charge in the trap for that particular segment. Conveniently, the adjustment of ionization parameters may be based on the previous analytical scan of the same mass segment.

Claims18

Dependent claims

A method of using a quadrupole ion trap mass spectrometer to detect the presence of any ions within a range of interest comprising the steps of:

(a) establishing a trapping field within the ion trap such that ions in said range of interest are stably held within the ion trap;
(b) introducing sample ions into the ion trap;
(c) isolating ions within a first mass range within said ion trap, said first mass range containing masses fewer than said range of interest;
(d) detecting the masses stored within the ion trap within said first mass range;
(e) substantially immediately thereafter introducing additional sample ions into the ion trap;
(f) isolating ions within a second mass range within said ion trap, said second mass range covering a range of masses substantially different than said first mass range;
and,
(g) detecting the masses stored within said ion trap within said second mass range, such that a mass spectrum of said first and second mass ranges is obtained.

5 more elements

Dependencies are inferred from the claim text.

Method of space charge control in an ion trap mass spectrometer

Life of this patent

Method of space charge control in an ion trap mass spectrometer

Life of this patent

Abstract

Claims18