Jet disrupter

In mass spectrometry, jet disrupters are specialized electrodes within ion funnels that counteract the effects of directed gas flow. Acting as physical barriers to neutral molecules, they disperse gas molecules and charged droplets while improving ion transmission and reducing vacuum system demands.[1][2][3]

Development and functionality

The development of the jet disrupter stemmed from the discovery that directed gas flow continued beyond both the capillary inlet and the ion funnel exit. This persistence caused inaccurate pressure readings, contamination of mass spectrometer components, increased background noise, and placed greater demand on downstream vacuum pumps.[4][5] To address these challenges posed by non-uniform gas pressures within ion funnels, the jet disrupter was introduced.[6]

The first jet disrupter was developed by Taeman Kim, consisting of a 9-mm brass disk positioned 22 mm downstream of the first ion funnel electrode. Operating at a higher voltage than the adjacent ring electrodes, this configuration enabled ions to be deflected around the electrode while causing neutral molecules and charged droplets to disperse and more efficiently be removed by vacuum pumps. Implementation of the jet disrupter in ion funnels yielded several improvements: downstream vacuum chamber pressure was reduced by a factor of 2-3, ion transmission improved by 15%, and MS/MS spectra demonstrated enhanced signal-to-noise ratios, increasing between 5.3 and 14.1-fold (depending on sample concentrations).[7]

Furthermore, jet disrupters can function as ion valves. By modulating the applied voltage, it is possible to control the transmission efficiency of ions through the funnel. This capability is particularly valuable for reducing the relative intensity of highly abundant analyte ions, which can rapidly fill ion trap analyzers and cause unwanted space charging effects, which occur when excessive ion populations degrade mass analyzer performance. Their application into ion cyclotron resonance (ICR) cells helped maintain optimal ion populations, improving mass accuracy and sensitivity.[8] The valve-like properties have also proven beneficial in dual-channel ion funnel designs, where a jet disrupter can modulate the flow of ions from one channel without affecting the ion transmission efficiency of the other.[9]

Problems and alternative technologies

While jet disrupters effectively manage directed gas flow and improve ion transmission, they face several operational challenges. Over time, the electrode surface becomes contaminated through exposure to liquid droplets and neutral molecules. Moreover, since jet disrupters cannot completely block these particles, some inevitably pass through to downstream components of the mass spectrometer, gradually degrading signal quality and necessitating periodic maintenance or cleaning.[10]

An alternative approach involves orthogonal ion injection, where the capillary input is orthogonally aligned with the ion funnel axis. Instead of using a physical barrier like a jet disrupter, this configuration allows the ion funnel to capture ions while naturally directing gas flow toward an outlet away from the funnel. This design effectively separates the gas dynamics from the ion path while maintaining ion transmission.[11]

References

1. Guo, Teng; Peng, Zhen; Zhu, Hui; Xu, Li; Dong, Jun-Guo; Huang, Zheng-Xu; Cheng, Ping; Zhou, Zhen (2019-01-01). "Research Progress and Application of Ion Funnel Technique". Chinese Journal of Analytical Chemistry. 47 (1): 13–22. doi:10.1016/S1872-2040(18)61133-8. ISSN 1872-2040.
2. Kelly, Ryan T.; Tolmachev, Aleksey V.; Page, Jason S.; Tang, Keqi; Smith, Richard D. (2010). "The ion funnel: Theory, implementations, and applications". Mass Spectrometry Reviews. 29 (2): 294–312. Bibcode:2010MSRv...29..294K. doi:10.1002/mas.20232. ISSN 1098-2787. PMC 2824015. PMID 19391099.
3. Julian, Ryan R.; Mabbett, Sarah R.; Jarrold, Martin F. (2005-10-01). "Ion funnels for the masses: Experiments and simulations with a simplified ion funnel". Journal of the American Society for Mass Spectrometry. 16 (10): 1708–1712. Bibcode:2005JASMS..16.1708J. doi:10.1016/j.jasms.2005.06.012. PMID 16095911.
4. Douglas, D. J.; French, J. B. (1988-01-01). "Gas dynamics of the inductively coupled plasma mass spectrometry interface". Journal of Analytical Atomic Spectrometry. 3 (6): 743–747. doi:10.1039/JA9880300743. ISSN 1364-5544.
5. Tejeda, G. (1996). "Temperature and Density Mapping of Supersonic Jet Expansions Using Linear Raman Spectroscopy". Physical Review Letters. 76 (1): 34–37. Bibcode:1996PhRvL..76...34T. doi:10.1103/PhysRevLett.76.34. hdl:10261/9023. PMID 10060427.
6. Shaffer, Scott A.; Prior, David C.; Anderson, Gordon A.; Udseth, Harold R.; Smith, Richard D. (1998-10-01). "An Ion Funnel Interface for Improved Ion Focusing and Sensitivity Using Electrospray Ionization Mass Spectrometry". Analytical Chemistry. 70 (19): 4111–4119. doi:10.1021/ac9802170. ISSN 0003-2700. PMID 9784749.
7. Kim, Taeman; Tang, Keqi; Udseth, Harold R.; Smith, Richard D. (2001-09-01). "A Multicapillary Inlet Jet Disruption Electrodynamic Ion Funnel Interface for Improved Sensitivity Using Atmospheric Pressure Ion Sources". Analytical Chemistry. 73 (17): 4162–4170. doi:10.1021/ac010174e. ISSN 0003-2700. PMID 11569805.
8. Page, Jason S.; Bogdanov, Bogdan; Vilkov, Andrey N.; Prior, David C.; Buschbach, Michael A.; Tang, Keqi; Smith, Richard D. (2005-02-01). "Automatic gain control in mass spectrometry using a jet disrupter electrode in an electrodynamic ion funnel". Journal of the American Society for Mass Spectrometry. 16 (2): 244–253. doi:10.1016/j.jasms.2004.11.003. PMC 1989159. PMID 15694774.
9. Tang, Keqi; Tolmachev, Aleksey V.; Nikolaev, Evgueni; Zhang, Rui; Belov, Mikhail E.; Udseth, Harold R.; Smith, Richard D. (2002-10-01). "Independent Control of Ion Transmission in a Jet Disrupter Dual-Channel Ion Funnel Electrospray Ionization MS Interface". Analytical Chemistry. 74 (20): 5431–5437. doi:10.1021/ac0202583. ISSN 0003-2700. PMID 12403604.
10. US20120298853A1, Kurulugama, Ruwan T. & Belov, Mikhail E., "Orthogonal ion injection apparatus and process", issued 2012-11-29 
11. Chen, Tsung-Chi; Fillmore, Thomas L.; Prost, Spencer A.; Moore, Ronald J.; Ibrahim, Yehia M.; Smith, Richard D. (2015-07-21). "Orthogonal Injection Ion Funnel Interface Providing Enhanced Performance for Selected Reaction Monitoring-Triple Quadrupole Mass Spectrometry". Analytical Chemistry. 87 (14): 7326–7331. doi:10.1021/acs.analchem.5b01482. ISSN 0003-2700. PMC 4776758. PMID 26107611.