Quadrupole Mass Filter Ion Trajectory Analysis
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Solution Overview
Problem
Conventional quadrupole mass spectrometers face a trade-off between instrument resolution and sensitivity, where high mass resolving power is achieved at the cost of low sensitivity and vice versa, due to the narrow or wide mass filter pass band, limiting the ability to accurately differentiate and quantify ions of different mass-to-charge ratios.
Innovation Solution
The method involves acquiring additional orthogonal data dimensions, such as varying the axial velocity and alternating between different scan lines in the Mathieu stability region, to enhance the separation and differentiation of ions, allowing for higher resolution and accuracy in mass spectrometry analysis.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the mass filter pass band is narrowed to achieve high mass resolving power, then measurement precision is improved, but sensitivity deteriorates
Solution Approach 1:
The patent transitions from conventional single-dimension mass filtering to a two-dimensional detection approach by recording both position and arrival time of ions. This dimensional expansion allows simultaneous achievement of high mass resolution and sensitivity by capturing ions across multiple parameters rather than filtering through a narrow mass window alone.
Solution Approach 2:
The patent employs dynamic voltage scanning through the Mathieu stability region, alternating between different scan lines and varying axial velocity. This dynamic approach enables the system to sweep through multiple mass ranges and collect ions that would otherwise be excluded by a static narrow pass band, thereby maintaining sensitivity while achieving high resolving power through post-acquisition analysis.
2Quantity of substance
If the mass filter pass band is widened to improve sensitivity, then quantity of substance is improved, but measurement precision deteriorates
Solution Approach 1:
By adding the time dimension to the detection process, the patent can accept a wider range of ions (improved sensitivity) while still achieving high mass resolution through temporal analysis. Ions are separated not only by spatial position but also by their arrival times, which correlate with their mass-to-charge ratios and trajectory characteristics.
Solution Approach 2:
The patent segments the ion population by recording their positions and arrival times separately, then reconstructing mass spectra through computational analysis. This segmentation allows the system to process a broad ion population (high sensitivity) while maintaining the ability to resolve individual mass components through their distinct temporal and spatial signatures.
3Measurement precision
If additional orthogonal data dimensions are acquired to enhance ion differentiation, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The patent employs a position-sensitive detector that inherently captures spatial distribution information without requiring additional complex instrumentation. The detector's natural capability to record ion positions and arrival times provides the orthogonal data dimensions needed for enhanced differentiation, avoiding the need for separate measurement systems.
Solution Approach 2:
The patent replaces complex mechanical or optical sorting systems with a computational approach. Instead of using additional physical components to separate and measure different ion parameters, the system uses mathematical analysis of position and time data to achieve high-resolution ion differentiation, substituting computational complexity for mechanical complexity.
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 approach enables higher resolution and more accurate results by capturing additional information about ion species, effectively overcoming the limitations of conventional methods by providing a more detailed understanding of ion trajectories and distributions within the quadrupole mass filter.
Implementation Method 1
applying an oscillatory radio frequency (RF) voltage, V, to rods of the quadrupole such that the instantaneous electrical potential of each rod is 180-degrees out of phase with each adjacent rod and a non-oscillatory voltage, U, across each pair of adjacent rods
Implementation Method 2
The DC offset on the x-rods is positive so that a positive ion feels a restoring force that tends to keep it near the z-axis; the potential in the x-direction is like a well. Conversely, the DC offset on the y-rods is negative so that a positive ion feels an outward-directed force
Implementation Method 3
acquiring a data set comprising a series of temporally-resolved images of spatial distribution patterns of the selectively transmitted ions
Data Source
AI summary
A method of mass analysis comprises: generating ions from the sample; delivering the ions to a quadrupole; applying a radio frequency voltage, V, to rods of the quadrupole such that the instantaneous electrical potential of each rod is out of phase with each adjacent rod and a non-oscillatory voltage, U, across each pair of adjacent rods such that a subset of the ions having a range of mass-to-charge (m/z) ratios are selectively transmitted through the quadrupole; varying at least one of voltage U and voltage V such that the range of selectively transmitted m/z ratios is caused to vary and varying at least one additional operational parameter; acquiring a data set comprising a series of temporally-resolved images of spatial distribution patterns of transmitted ions at each combination of U, V and the at least one additional operating parameter; and mathematically deconvolving the data set to generate mass spectra.