Ion Mobility Filtration for Mass Spectrometer Contamination Control
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Solution Overview
Problem
Mass spectrometry systems face contamination and reduced sensitivity due to high mass and low mass ions generated by atmospheric pressure ionization sources, which interfere with analysis and degrade the vacuum system, necessitating improved methods to filter out unwanted ions while maintaining transmission efficiency.
Innovation Solution
A low resolution, high transmission ion mobility spectrometer is configured to filter out high mass and low mass ions by controlling residence time, gap height, and separation voltage, ensuring that ions of interest pass through with minimal loss, thereby maintaining system performance and extending maintenance intervals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If atmospheric pressure ionization sources are used to generate ions, then ion current efficiency is improved, but contamination of ion optics and vacuum system degradation occur
Solution Approach 1:
The patent extracts and removes unwanted high mass and low mass ions from the ion beam using an ion mobility spectrometer positioned between the atmospheric pressure ion source and the mass analyzer. This separation allows the beneficial ion current from the atmospheric pressure source to be maintained while extracting the harmful contaminating ions that would otherwise degrade the vacuum system and contaminate ion optics.
Solution Approach 2:
The ion mobility spectrometer acts as an intermediary device between the atmospheric pressure ion source and the high vacuum mass analyzer. It provides a transition zone where ions are separated by mobility characteristics, allowing selective transmission of desired ions while blocking contaminating ions, thus protecting the downstream vacuum system without sacrificing the efficiency of the atmospheric pressure ionization.
2Measurement precision
If ion mobility spectrometer operates with high resolution parameters, then separation of charged species is improved, but transmission of ions of interest decreases
Solution Approach 1:
The patent applies different operational characteristics to different regions of the ion mobility spectrum. By configuring the ion mobility spectrometer with specific drift tube dimensions, electric field strengths, and gas flow rates, it creates localized separation zones that provide sufficient resolution for contaminant removal while maintaining high transmission for the bulk of analyte ions. The system optimizes parameters locally rather than uniformly across all ion types.
Solution Approach 2:
The ion mobility spectrometer is configured to provide partial separation - sufficient to remove high mass and low mass contaminants but not excessive enough to significantly reduce transmission of analyte ions. The operating parameters are tuned to achieve just enough resolution to filter contaminants while maintaining high ion throughput, applying the principle of doing only what is necessary rather than maximizing separation at the cost of transmission.
3Measurement precision
If ion mobility spectrometer is configured to filter high mass and low mass ions, then sensitivity is improved, but device complexity increases
Solution Approach 1:
The ion mobility spectrometer is configured to perform multiple functions simultaneously: it filters high mass ions, filters low mass ions, and transmits analyte ions, all within a single device. This multi-functionality achieves sensitivity improvement through comprehensive contaminant removal without requiring multiple separate filtering devices, thereby limiting the increase in overall system complexity.
Solution Approach 2:
The patent achieves contaminant filtering by adjusting key parameters of the ion mobility spectrometer including drift tube length, electrode spacing, gas flow rate, and electric field strength. By optimizing these parameters, the system enables effective separation of high mass and low mass ions while maintaining a relatively simple device configuration that does not require complex mechanical structures or multiple processing stages.
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
This configuration effectively reduces unwanted ion contamination, improving sensitivity and extending the time between maintenance cycles by filtering out up to 99% of unwanted ions while allowing analytes of interest to reach the mass analyzer, thus maintaining peak performance of the mass spectrometer.
Implementation Method 1
ion mobility spectrometry (IMS) and other ion mobility separation techniques separate ions based upon other factors such as size, shape, and charge state as ions drift through a gas (typically at atmospheric pressure) in an electric field
Implementation Method 2
ions drift through a gas (typically at atmospheric pressure) in an electric field. The drift time through an electrostatic field is characteristic of the mobility of the ion
Data Source
Figure 1(A)~2
Figure 3~4b
Figure 5~6b
AI summary
Methods and systems for performing mass spectrometry are provided herein. In accordance with various aspects of the applicants' teachings, the methods and systems can utilize an ion mobility spectrometer operating at atmospheric or low- vacuum pressure to remove the major contributors to the contamination and degradation of critical downstream components of a mass spectrometer located within a high-vacuum system (e.g., ion optics, mass filters, detectors), with limited signal loss.