Quadrupole Ion Guide Using Notched Broadband RF Signals
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Solution Overview
Problem
Conventional quadrupole rod set mass filters have limitations in simultaneously transmitting multiple ions with different mass-to-charge ratios while effectively attenuating others, leading to reduced duty cycle and specificity when operating in high-resolution mode, and inefficient ion transmission across a wide range of mass-to-charge ratios in low-resolution mode.
Innovation Solution
A quadrupole ion guide or mass filter device employing a notched broadband frequency signal applied to its rods, which resonantly excites and ejects undesired ions while allowing desired ions to pass through, creating discrete and non-overlapping mass-to-charge ratio transmission windows to selectively transmit specific ions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a quadrupole rod set mass filter operates in high-resolution mode to selectively transmit ions with specific mass-to-charge ratios, then measurement precision is improved, but productivity deteriorates due to reduced duty cycle
Solution Approach 1:
The patent applies periodic RF voltages at resonant frequencies to the quadrupole rods to selectively eject ions. By using periodic action with notched broadband frequency signals, the system can rapidly scan through different mass-to-charge ratios and efficiently eject unwanted ions, thereby improving the duty cycle while maintaining high-resolution mass selection capability
Solution Approach 2:
The patent dynamically changes the RF voltage parameters (frequency, amplitude, and phase) applied to the quadrupole rods to optimize ion transmission. By adjusting these parameters in real-time according to the desired mass-to-charge ratio, the system achieves both high measurement precision and improved productivity through efficient ion selection
2Productivity
If a quadrupole rod set mass filter transmits ions across a wide range of mass-to-charge ratios simultaneously, then productivity is improved, but measurement precision deteriorates
Solution Approach 1:
The patent extracts or removes specific frequency components (notches) from the broadband RF signal applied to the quadrupole rods. By taking out the resonant frequencies corresponding to unwanted ions, the system can transmit desired ions across a wide mass-to-charge ratio range while selectively ejecting specific interfering ions, thus maintaining both productivity and measurement precision
3Ease of operation
If a quadrupole rod set uses conventional RF signaling to guide ions, then ease of operation is maintained, but object-generated harmful factors worsen due to inability to resonantly eject undesired ions
Solution Approach 1:
The patent employs periodic RF signals with specific notched frequency components applied to the quadrupole rods. This periodic action resonantly excites undesired background ions, causing them to be ejected radially from the ion guide, thereby eliminating harmful interference while maintaining ease of operation through automated signal control
Solution Approach 2:
The patent uses vibrational resonance of ions by applying RF signals at their characteristic resonant frequencies. The notched broadband signal causes undesired ions to vibrate resonantly and be ejected, while desired ions remain unaffected. This approach effectively removes harmful factors without complicating the operation
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 the simultaneous transmission of multiple ions with distinct mass-to-charge ratios while attenuating intermediate ions, improving specificity and duty cycle by ensuring only desired ions are onwardly transmitted, thereby enhancing the ion guide's ability to handle a continuum of mass-to-charge ratios.
Implementation Method 1
a notched broadband frequency signal is applied to the rods of the quadrupole rod set which resonantly excites and radially ejects undesired background ions present in the ion guide
Implementation Method 2
Adjacent rods are arranged to have opposite phases of the RF signal or voltage applied to them. The application of the RF signal or voltage to the rods results in a radial pseudo-potential well being generated which acts to confine ions radially within the quadrupole rod set
Implementation Method 3
By applying an RF voltage to the rods and maintaining a DC potential difference between adjacent rods the quadrupole rod set can be arranged to act as a mass filter such that only ions having mass to charge ratios falling within well defined upper and lower mass to charge ratio cut-offs are transmitted
Data Source
AI summary
A mass spectrometer is disclosed comprising a quadrupole rod set ion guide or mass filter device (6). A broadband frequency signal (10) having one or more notches (11a, 11b, 11c) is applied to the rods of the quadrupole rod set (6). The notched broadband frequency signal (10) causes undesired ions to be resonantly ejected from the ion guide (6). The notched broadband frequency signal (10) has frequency components missing which correspond with the resonance frequency of ions which are desired to be onwardly transmitted. The ion guide or mass filter device (6) enables a plurality of desired ions having different mass to charge ratios to be simultaneously transmitted by the ion guide or mass filter device (6) whilst other ions are resonantly ejected from the ion guide or mass filter device (6).