Quadrupole Mass Filter Spatial-Temporal Ion Detection
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Solution Overview
Problem
Conventional quadrupole mass spectrometers face a trade-off between high mass resolving power and sensitivity, often requiring a compromise where either high resolving power is achieved at the expense of sensitivity or vice versa, and typically operate at slow scan rates.
Innovation Solution
A novel quadrupole mass filter system that records ion arrival times and positions as a function of applied RF and DC fields, allowing for the deconvolution of ion images to extract individual ion species' mass-to-charge ratios and abundances, enabling high mass resolving power and sensitivity simultaneously at higher scan rates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If narrow mass stability limits are used to enhance mass resolving power, then mass resolving power is improved, but sensitivity deteriorates
Solution Approach 1:
The patent transitions from conventional single-point detection to a two-dimensional position-sensitive detector that records both spatial position and arrival time of ions. This dimensional expansion allows simultaneous measurement of multiple ions with different trajectories, enabling high mass resolving power through spatial separation while maintaining sensitivity by detecting all transmitted ions across the detection plane.
Solution Approach 2:
The detection process is segmented into multiple spatial zones on the detector surface, where different regions correspond to ions with different mass-to-charge ratios. By dividing the detection space and assigning specific zones to specific mass ranges, the system achieves high mass resolving power without sacrificing the total number of detected ions, thus maintaining sensitivity.
2Measurement precision
If conventional single detector operation is used, then device complexity is low, but measurement precision deteriorates
Solution Approach 1:
The position-sensitive detector serves multiple functions simultaneously: it acts as a mass filter, a spectrometer, and a spatial analyzer all in one device. By recording both the position and arrival time of ions, the detector provides comprehensive mass spectral information without requiring separate instruments, thereby improving measurement precision while keeping the overall device configuration relatively simple.
3Measurement precision
If slow scan rates are used to improve measurement precision, then mass resolving power is improved, but productivity deteriorates
Solution Approach 1:
The system employs periodic RF and DC voltage applications to the quadrupole rods, creating oscillating electric fields that systematically vary the mass stability limits over time. This periodic action allows rapid scanning through different mass ranges while maintaining measurement precision through the position-sensitive detection of ions at each phase of the cycle, thereby achieving both high productivity and measurement precision.
Solution Approach 2:
The position-sensitive detector pre-records spatial distribution information of ions during their transit through the quadrupole, before final mass analysis is completed. This preliminary spatial mapping allows for faster data acquisition and processing, enabling higher scan rates without sacrificing the precision of mass-to-charge ratio determination.
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 allows for comprehensive mass data acquisition with high time resolution, improving sensitivity and mass resolving power while reducing manufacturing tolerances and costs, enabling applications such as petroleum and drug analysis that were previously inaccessible with quadrupole systems.
Implementation Method 1
by applying fixed and/or ramped AC and DC voltages to configured cylindrical but more often hyperbolic electrode rod pairs in a manner known to those skilled in the art, desired electrical fields are set-up to stabilize the motion of predetermined ions in the x and y dimensions
Implementation Method 2
The applied electrical field in the x-axis stabilizes the trajectory of heavier ions, whereas the lighter ions have unstable trajectories. By contrast, the electrical field in the y-axis stabilizes the trajectories of lighter ions, whereas the heavier ions have unstable trajectories
Implementation Method 3
a detector configured to record the spatial and temporal properties of the abundance of ions at a cross-sectional area of the multipole
Data Source
AI summary
A novel method and mass spectrometer apparatus is introduced to spatially and temporally resolve images of one or more ion exit patterns of a multipole instrument. In particular, the methods and structures of the present invention measures the ion current as a function of time and spatial displacement in the beam cross-section of a quadrupole mass filter via an arrayed detector. The linearity of the detected quadrupole ion current in combination with it reproducible spatial-temporal structure enables the deconvolution of the contributions of signals from individual ion species in complex mixtures where both sensitivity and mass resolving power are essential.