Orthogonal Ion Injection for Mass Spectrometer Signal Stability
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Solution Overview
Problem
Conventional inline capillary injection methods in mass spectrometers lead to contamination of downstream components due to incompletely desolvated liquid droplets, resulting in unstable signals and signal loss, especially with multiple inlet capillaries which increase gas loads beyond the capacity of existing DC field diversion methods.
Innovation Solution
An orthogonal ion injection system using a stacked electrode lens ion guide with both DC and RF potentials, combined with a shielded inlet capillary, effectively directs ions into the ion guide while removing excess gas and liquid droplets, minimizing contamination and enhancing signal stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If multiple inlet capillaries are used to increase analyte signal, then ion signal intensity is improved, but gas load increases causing rapid contamination of downstream mass spectrometer elements
Solution Approach 1:
The patent transitions from inline (collinear) ion injection to orthogonal ion injection, changing the spatial dimension of ion introduction. The inlet capillary is positioned perpendicular to the ion guide axis, allowing ions to enter the ion guide from the side rather than from the end. This dimensional change enables effective separation of ion transport from gas/droplet flow, solving the contamination problem while maintaining high signal intensity.
Solution Approach 2:
The patent divides the ion introduction system into separate functional zones: the inlet capillary region for ion generation, the orthogonal injection region for ion introduction, and the ion guide region for ion transport. This segmentation allows each component to perform its function independently, preventing contamination propagation from the inlet region to downstream components.
2Reliability
If DC field is increased to divert ions into ion funnel at higher gas loads, then ion diversion efficiency is improved, but electrical discharge occurs limiting the maximum DC field
Solution Approach 1:
The patent replaces the DC field diversion method with orthogonal ion injection, changing the mechanism from field-based diversion to geometry-based introduction. The orthogonal capillary configuration naturally directs ions into the ion guide without requiring strong DC fields, eliminating electrical discharge while maintaining effective ion diversion.
Solution Approach 2:
The patent introduces the orthogonal inlet capillary as an intermediary structure that mediates ion introduction. Instead of relying on strong DC fields to divert ions, the capillary's physical configuration serves as the intermediary to guide ions into the ion guide, reducing the need for high electric fields and preventing electrical discharge.
3Ease of operation
If inline capillary is used to introduce ions, then ion introduction is simple, but incompletely desolvated liquid droplets are carried into mass spectrometer causing contamination
Solution Approach 1:
The patent changes the injection geometry from inline to orthogonal, positioning the inlet capillary perpendicular to the ion guide axis. This dimensional change allows liquid droplets to be deposited on the ion guide wall or diverted by the electric field, while ions are effectively introduced into the ion guide, separating ion transport from droplet contamination.
Solution Approach 2:
The patent extracts the harmful liquid droplets from the ion beam path by using orthogonal injection. The droplets are deposited on the ion guide wall or diverted away from the ion guide axis, while ions continue into the ion guide, effectively separating the useful ion signal from the harmful droplet contamination.
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 system achieves improved ion transmission efficiency and reduced noise levels, maintaining signal intensity and stability even with higher gas loads, compared to conventional inline injection methods.
Implementation Method 1
Each electrode lens includes a preselected diameter, an entrance end, and an exit end. The electrode lenses collectively define an ion guide axis through the center of the ion guide.
Implementation Method 2
an orthogonal ion injection device and process for introducing ions into an ion guide that minimizes contamination of downstream mass spectrometer elements
Implementation Method 3
electrode elements of the ion guide include both a DC and an RF potential, which minimizes risk of contamination in downstream electrode elements and MS components
Implementation Method 4
The inlet capillary inserts through an opening at a preselected location downstream from a first electrode lens on one side of the ion guide introducing ions into the interior of the ion guide orthogonal to the ion guide axis
Implementation Method 5
The opening includes a shield that covers the opening composed of an insulating material. In a preferred embodiment, the shield is composed of a poly-ether-ether-ketone (PEEK) polymer.
Data Source
AI summary
An orthogonal ion injection apparatus and process are described in which ions are directly injected into an ion guide orthogonal to the ion guide axis through an inlet opening located on a side of the ion guide. The end of the heated capillary is placed inside the ion guide such that the ions are directly injected into DC and RF fields inside the ion guide, which efficiently confines ions inside the ion guide. Liquid droplets created by the ionization source that are carried through the capillary into the ion guide are removed from the ion guide by a strong directional gas flow through an inlet opening on the opposite side of the ion guide. Strong DC and RF fields divert ions into the ion guide. In-guide orthogonal injection yields a noise level that is a factor of 1.5 to 2 lower than conventional inline injection known in the art. Signal intensities for low m/z ions are greater compared to convention inline injection under the same processing conditions.