Quadrupole Mass Spectrometer Baseline Noise Reduction
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Solution Overview
Problem
Existing quadrupole mass spectrometers face challenges in achieving an appropriate baseline process due to high-intensity signals at small mass-to-charge ratios, which complicates noise reduction and offset correction, particularly when methods to block ions from reaching the detector are ineffective.
Innovation Solution
A quadrupole mass spectrometer with a filter voltage controller that switches between a blocking mode and a passing mode, where the filter voltage is controlled to prevent ions from impinging on the detector in the blocking mode by destabilizing ion oscillations or altering their trajectories, allowing for a baseline computation based on detector outputs during the blocking mode, ensuring noise reduction and improved analysis results.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the blocking period is achieved by changing the potential of a post-filter or the difference in potential between the ion source and the filter unit, then ions are prevented from entering the filter unit or impinging on the detector, but a high-intensity signal is generated at small mass-to-charge ratios that complicates baseline processing
Solution Approach 1:
The patent changes the parameters of the filter voltage (RF and DC components) to switch between passing mode and blocking mode. In blocking mode, specific voltage parameters are applied to the quadrupole to prevent ions from reaching the detector, effectively eliminating the high-intensity signal problem at small mass-to-charge ratios while enabling accurate baseline processing
2Object-affected harmful factors
If ions are blocked from impinging on the detector during baseline process, then noise from neutral molecules can be reduced, but the filter voltage must be precisely controlled to ensure complete ion blocking
Solution Approach 1:
The patent employs periodic switching between passing mode and blocking mode through time-multiplexed filter voltage control. The filter voltage is periodically changed to create distinct time periods for ion detection and baseline measurement, enabling effective noise reduction while managing control complexity through systematic voltage switching protocols
3Measurement precision
If the filter voltage is swept from lower to higher values to obtain mass spectrum, then mass separation is achieved, but the baseline process becomes complicated by the presence of ion signals during the sweep
Solution Approach 1:
The patent segments the measurement process into distinct time periods: passing periods for ion detection and baseline measurement, and blocking periods for baseline-only measurement. This temporal segmentation allows the mass spectrum acquisition and baseline process to be performed in separate time windows, eliminating the complication of ion signals during baseline measurement while maintaining mass separation accuracy
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 effectively blocks ions from the detector during the baseline process, reducing noise and improving the reliability of sample analysis results by ensuring a more accurate baseline, leading to clearer peak separation for each mass-to-charge ratio.
Implementation Method 1
a filter unit including a quadrupole and configured to separate ions generated from the ion source according to mass
Implementation Method 2
The filter voltage is a combination of a radio-frequency (RF) voltage and a direct-current (DC) voltage at a predetermined ratio based on the Mathieu equation
Implementation Method 3
an ion source configured to ionize a sample
Implementation Method 4
a detector configured to detect ions passing through the filter unit
Implementation Method 5
controlling a filter voltage applied to the quadrupole to switch between a blocking mode in which ions entering the filter unit are not allowed to impinge on the detector
Data Source
AI summary
A quadrupole mass spectrometer includes an ion source that ionizes a sample, a filter unit that includes a quadrupole and separates ions generated from the ion source according to mass, a detector that detects ions passing through the filter unit, a filter voltage controller that controls a filter voltage applied to the quadrupole to switch between a blocking mode in which ions entering the filter unit are not allowed to impinge on the detector and a passing mode in which ions entering the filter unit are allowed to impinge on the detector, the filter voltage including a radio-frequency voltage and a direct-current voltage, a baseline computing unit that computes a baseline based on outputs of the detector in the blocking mode, and an analyzing unit that outputs an analysis result of the sample based on outputs of the detector in the passing mode and the computed baseline.