Method of separating different ions having similar mass to charge ratios
AssigneeMicromass UK Limited
InventorsBoris Kozlov, David J. Langridge
Life of this patent
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Abstract
A method of filtering ions (16) is disclosed comprising: providing an ion filter (6) having an ion entrance, an ion exit and a plurality of electrodes (18); applying an AC and/or RF voltage to at least a first electrode so as to generate a pseudo-potential barrier; and urging ions towards the pseudo-potential barrier as they travel from the entrance to the exit whilst maintaining the ion filter (6) at a pressure such that first ions are repelled by the pseudo-potential barrier and so are transmitted through the filter to said exit, whereas second ions having substantially the same mass to charge ratio as the first ions but a lower mass are not capable of being repelled by the pseudo-potential barrier and reaching said exit.
Claims20
A method of filtering ions comprising:
- providing an ion filter having an ion entrance, an ion exit and a plurality of electrodes;
- applying an AC and/or RF voltage to at least a first electrode so as to generate a pseudo-potential barrier;
- and
- urging ions towards the pseudo-potential barrier as they travel from the entrance to the exit whilst maintaining the ion filter at a pressure such that:
- first ions are prevented from passing through the pseudo-potential barrier by being repelled by the pseudo-potential barrier and so are transmitted through the filter to said exit, whereas second ions having substantially the same mass to charge ratio as the first ions but a lower mass are not prevented from passing through the pseudopotential barrier by being repelled by the pseudo-potential barrier, such that the second ions pass through the pseudo-potential barrier and out of the ion filter without reaching said exit.
An ion filter comprising:
- an ion entrance, an ion exit and a plurality of electrodes;
- a voltage supply for applying an AC and/or RF voltage to at least a first of the electrodes so as to generate a pseudo-potential barrier;
- a gas control mechanism for controlling the gas pressure within the ion filter;
- and
- a controller configured and set up to:
- control the ion filter so as to urge ions towards the pseudo-potential barrier as they travel from the ion entrance towards the ion exit and control the gas control mechanism so as to maintain the ion filter at a pressure such that:
- first ions are prevented from passing through the pseudo-potential barrier by being repelled by the pseudo-potential barrier such that the first ions are transmitted through the filter to said exit, whereas second ions having substantially the same mass to charge ratio as the first ions but a lower mass are not prevented from passing through the pseudo-potential barrier by being repelled by the pseudo-potential barrier, such that the second ions pass through the pseudo-potential barrier and out of the ion filter without reaching said exit.
A method of filtering ions comprising:
- providing an ion filter having an ion entrance, an ion exit and a plurality of electrodes, wherein an ion transmission axis through the ion filter joins the ion entrance and the ion exit;
- urging a plurality of ions to travel from the ion entrance along the ion transmission axis towards the ion exit, the plurality of ions comprising first ions and second ions, wherein the second ions have substantially the same mass to charge ratio as the first ions but a lower mass than the first ions;
- applying an AC and/or RF voltage to at least a first electrode of the plurality of electrodes so as to generate a pseudo-potential barrier around the ion transmission axis for inhibiting the motion of ions radially outwards from within the ion filter;
- and
- urging the plurality of ions radially outwards towards the pseudo-potential barrier as they travel from the ion entrance towards the ion exit whilst maintaining the ion filter at a pressure, wherein the pressure is such that, when the plurality of ions are urged radially outwards towards the pseudo-potential barrier:
- the first ions are prevented from passing through the pseudo-potential barrier by being repelled by the pseudo-potential barrier such that the first ions are maintained within the ion filter until the first ions are transmitted along the ion transmission axis through the ion filter to said ion exit, whereas the second ions are not prevented from passing through the pseudo-potential barrier by being repelled by the pseudo-potential barrier such that the second ions are not maintained within the ion filter and do not reach said ion exit.
Dependencies are inferred from the claim text.