US RE50,588 E1
Ion trapping scheme with improved mass range
Dirk Nolting, Bremen (DE); Alexander A. Makarov, Bremen (DE); and Amelia Corinne Peterson, Bremen (DE)
Assigned to THERMO FISHER SCIENTIFIC (BREMEN) GMBH, Bremen (DE)
Filed by Thermo Fisher Scientific (Bremen) GmbH, Bremen (DE)
Filed on Jun. 6, 2023, as Appl. No. 18/206,463.
Application 18/206,463 is a reissue of application No. 16/815,811, filed on Mar. 11, 2020, granted, now 11,515,138, issued on Nov. 29, 2022.
Claims priority of application No. 1903474 (GB), filed on Mar. 14, 2019.
Int. Cl. H01J 49/42 (2006.01)
CPC H01J 49/4225 (2013.01) [H01J 49/426 (2013.01)] 53 Claims
OG exemplary drawing
 
1. A method of trapping ions in an ion trapping assembly, the method comprising:
(a) introducing ions into the ion trapping assembly, wherein the ion trapping assembly comprises an ion trap and an ion cooling device,
(b) applying a first RF trapping amplitude to the ion trapping assembly, so as to trap introduced ions which have m/z ratios within a first range of m/z ratios;
(c) cooling the trapped ions;
(d) reducing the RF trapping amplitude from the first RF trapping amplitude to a second, lower, RF trapping amplitude so as to reduce the low mass cut-off of the ion trapping assembly; and
(e) trapping, at the second, lower RF trapping amplitude, introduced ions having m/z ratios within a second range of m/z ratios;
wherein a lower mass limit of the second range of m/z ratios is below the low mass cut-off of the ion trapping assembly when the first RF trapping amplitude is applied,
wherein in step (b), the first RF trapping amplitude is applied to the ion cooling device such that ions which have m/z ratios within the first range of m/z ratios are trapped in the ion cooling device;
wherein in step (c), the trapped ions are cooled in the ion cooling device;
wherein after step (c) and before step (d), the method comprises step (c)(i) comprising transferring the trapped ions from the ion cooling device to the ion trap whilst applying the first RF trapping amplitude to the ion cooling device and whilst applying a corresponding first RF trapping amplitude to the ion trap, such that the ion trap and the ion cooling device have the same low mass cut-off during the transfer of ions in step (c)(i), trapping, at the corresponding RF trapping amplitude, the transferred ions in the ion trap;
wherein in step (d), the RF trapping amplitude applied to the ion trap is reduced to the second, lower, RF trapping amplitude so as to reduce the low mass cut-off of the ion trap.