Li M, Liu X, Zhou X, Ouyang Z. Ion-Neutral Collision Effects on Ion Trapping and Pseudopotential Depth in Ion Trap Mass Spectrometry.
JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY 2019;
30:2750-2755. [PMID:
31659717 DOI:
10.1007/s13361-019-02344-x]
[Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/25/2019] [Revised: 09/07/2019] [Accepted: 09/25/2019] [Indexed: 06/10/2023]
Abstract
Ion trapping using radio-frequency (RF) devices has been widely used in mass spectrometry (MS). The pseudopotential well (PW) model enables the use of a pseudopotential depth, D, to evaluate the ion trapping capability of the RF devices in the pure electric field. It remains unclear how gas pressures regulate the ion trapping and D. Here, we calculated the D of a linear ion trap (LIT) from 1 mTorr to 2 Torr, a pressure range critical for the operation of the RF devices, through ion cloud simulations. Compared with the case of pure electric field, ion-neutral collision effects at pressures of 1 to 100 mTorr were beneficial for the ion trapping and revealed an optimal trapping depth, D, at around 10 mTorr. We explained the mechanism and validated the observation via ion trapping experiments performed in a home-made dual LIT mass spectrometer. We also showed that near the stability boundary, the RF heating became comparable with the D, which led to the decrement of ion trapping capability characterized by the available D.
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