Quadrupole Mass Spectrometer Dynamic Bias Voltage Control
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Solution Overview
Problem
Conventional quadrupole mass spectrometers face reduced detection sensitivity due to ions not meeting the phase condition for entering the quadrupole mass filter, especially when mass-to-charge ratios vary, leading to inefficient ion passage and mass resolution issues.
Innovation Solution
A quadrupole mass spectrometer with a multipole pre-filter and a controller that adjusts the direct current bias voltage based on the mass-to-charge ratio, ensuring uniform ion flight speed and phase at the pre-filter exit, thereby optimizing ion passage into the quadrupole mass filter.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If a pre-filter is provided in the previous stage of the quadrupole mass filter with a constant direct current bias voltage, then the ion passage ratio is increased, but the detection sensitivity varies depending on the mass-to-charge ratio due to phase differences in ion oscillation
Solution Approach 1:
The patent applies dynamics by making the direct current bias voltage variable rather than constant. The voltage is dynamically adjusted based on the mass-to-charge ratio of ions to be analyzed, allowing the system to adapt to different ion types and maintain optimal performance across varying mass ranges.
Solution Approach 2:
The patent changes the parameter of direct current bias voltage from a fixed value to a variable value that depends on the mass-to-charge ratio. This parameter change enables the pre-filter to compensate for mass-dependent phase differences in ion oscillation, ensuring consistent detection sensitivity across different mass ranges.
2Productivity
If the direct current bias voltage is increased to improve ion passage efficiency, then more ions enter the quadrupole mass filter, but the potential barrier increases which may decrease sensitivity for certain mass ranges
Solution Approach 1:
The patent applies parameter changes by adjusting the direct current bias voltage according to the mass-to-charge ratio. This allows optimization of ion passage efficiency for each specific mass range without creating excessive potential barriers that would hinder sensitivity.
Solution Approach 2:
The patent applies local quality by tailoring the voltage conditions specifically for different mass ranges. Each mass range receives optimized voltage parameters, ensuring that the pre-filter conditions are locally optimized for the specific ions being analyzed rather than using a one-size-fits-all approach.
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 enhances detection sensitivity by ensuring high ion passage efficiency and maintaining mass resolution across varying mass-to-charge ratios, while preventing potential barrier increases that could decrease sensitivity.
Implementation Method 1
A voltage of ±(U+V·cos ωt) is applied to each of the four rod electrodes, in which a direct current voltage U and a radio-frequency voltage V·cos ωt are superimposed. This voltage forms a radio-frequency electric field and a direct current electric field in the space surrounded by the four rod electrodes.
Implementation Method 2
A voltage of ±(U+V·cos ωt) is applied to each of the four rod electrodes, in which a direct current voltage U and a radio-frequency voltage V·cos ωt are superimposed. This voltage forms a radio-frequency electric field and a direct current electric field in the space surrounded by the four rod electrodes.
Implementation Method 3
an ion passing through the pre-filter 13 flies, as schematically illustrated in FIG. 7(a), while periodically oscillating with a period of T=1/f [sec] for the frequency f of the radio-frequency voltage applied to the pre-rod electrodes
Data Source
AI summary
The direct current bias voltage to be applied to the pre-filter provided in the previous stage of the quadrupole mass filter for selecting an ion according to the mass-to-charge ratio is changed in accordance with the mass-to-charge ratio of the target ion to be allowed to pass through, in order that the time period required for an ion to pass through the pre-filter is uniformed regardless of the mass-to-charge ratio, and simultaneously the phase of the oscillation of ions at the entrance of the quadrupole mass filter is also uniformed. In the range where the mass-to-charge ratio is larger than some degree, the ion's oscillation itself is small, and in addition, the ion's passage efficiency deteriorates rather than enhances, due to the potential barrier created by the voltage difference from the direct current bias voltage applied to the quadrupole mass filter.