Ion Funnel Spacer Elements for Low m/z Ion Transmission
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Solution Overview
Problem
Existing atmospheric pressure ionization techniques face challenges in efficiently transferring low abundance analyte ions from atmospheric pressure to the vacuum environment of a mass spectrometer, particularly for portable systems with size and weight limitations, where RF potentials create an effective potential barrier preventing low mass-to-charge ratio ion transmission.
Innovation Solution
An ion funnel with a plurality of spacer elements coaxially disposed with electrodes, where each spacer element has an aperture larger than the adjacent electrodes, facilitating gas dynamics and overcoming the RF potential barrier to enable efficient transmission of low m/z ions by creating a gas-tight interface and applying RF and DC electric fields.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If RF potentials are applied to electrodes in the ion funnel, then ion confinement and focusing are improved, but low mass-to-charge ratio ion transmission is blocked due to effective potential barrier
Solution Approach 1:
A gas-tight interface is introduced as an intermediary mechanism between the RF electrodes. This interface uses controlled gas flow dynamics to create a pressure gradient that enables low m/z ions to overcome the RF potential barrier and pass through the ion funnel, while the RF fields continue to provide ion confinement and focusing.
Solution Approach 2:
The system changes the pressure parameter within the ion funnel by controlling gas flow through the gas-tight interface. By optimizing the pressure gradient, low m/z ions gain sufficient kinetic energy to traverse the RF potential barrier, resolving the contradiction between maintaining RF confinement and enabling low m/z transmission.
2Productivity
If ion funnel pressure is increased to improve low m/z ion transmission, then detection efficiency is improved, but gas flow rate increases requiring larger vacuum pumps
Solution Approach 1:
The gas-tight interface is nested within the ion funnel structure, creating a localized pressure control zone. This nested design allows high pressure (for improved low m/z transmission) to be contained within the ion funnel while the overall system maintains lower gas flow requirements, enabling the use of smaller vacuum pumps.
Solution Approach 2:
The system applies local quality by creating a high-pressure region specifically within the ion funnel where it is needed for low m/z ion transmission, while the rest of the system operates at lower pressures. This localized pressure enhancement improves detection efficiency without proportionally increasing the overall gas flow rate.
3Weight of stationary object
If portable system size and weight are reduced, then system portability is improved, but vacuum pump size must be reduced which limits pressure control capability
Solution Approach 1:
The gas-tight interface enables effective pressure control within the ion funnel using smaller vacuum pumps. By optimizing the gas flow dynamics and pressure gradient through the interface, the system achieves the necessary pressure conditions for low m/z ion transmission with reduced pump capacity, thereby reducing overall system weight while maintaining adaptability.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The design enhances ion acceptance and transmission of low m/z ions into the next vacuum stage, improving detection efficiency while allowing the use of small vacuum pumps, as demonstrated by increased relative abundance of ions measured at higher ion funnel pressures.
Implementation Method 1
applying RF and DC electric fields
Implementation Method 2
applying RF and DC electric fields
Implementation Method 3
facilitating gas dynamics and overcoming the RF potential barrier
Implementation Method 4
facilitating gas dynamics
Data Source
AI summary
A sample inlet device and methods for use of the sample inlet device are described that include an ion funnel having a plurality of electrodes with apertures arranged about an axis extending from an inlet of the ion funnel to an outlet of the ion funnel, the ion funnel including a plurality of spacer elements disposed coaxially with the plurality of electrodes, each of the plurality of spacer elements being positioned between one or two adjacent electrodes, each of the plurality of spacer elements having an aperture with a diameter that is greater than a diameter of each adjacent electrode. The ion funnel is configured to pass an ion sample through the apertures of the electrodes and the spacer elements to additional portions of a detection system, such as to a mass analyzer system and detector.