Abridged RF Multipole Ion Guide for Mass Spectrometry
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Solution Overview
Problem
Existing mass spectrometry techniques face challenges in efficiently transporting and analyzing ions, particularly for fragile and labile molecules, due to energy deposition during ionization processes, which leads to fragmentation and loss of molecular weight information.
Innovation Solution
The development of an abridged quadrupole mass spectrometer with a rectilinear electrode arrangement and a specific potential distribution that creates a homogeneous electrostatic and electrodynamic field, allowing for efficient ion transport and analysis without the need for DC trapping electrodes, and enabling the use of multiple frequency multipole fields to confine ions of varying m/z ratios.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If SIMS process uses keV ions to desorb and ionize sample material, then ionization efficiency is improved, but fragmentation of fragile molecules occurs resulting in loss of molecular weight information
Solution Approach 1:
The patent changes the energy parameter from keV (SIMS) to MeV (plasma desorption), and later to infrared laser wavelengths for MALDI. This parameter change allows ionization of fragile molecules without excessive energy deposition that causes fragmentation, thereby preserving molecular weight information while maintaining ionization efficiency
Solution Approach 2:
The patent introduces a matrix substance in MALDI that acts as an intermediary between the laser and the analyte molecules. The matrix absorbs the laser energy and facilitates gentle ionization of fragile molecules through proton transfer, preventing direct energy damage to the analyte and preserving molecular integrity
2Quantity of substance
If plasma desorption uses MeV ions to desorb and ionize sample material, then desorption of larger labile species is improved, but energy deposition in analyte molecules increases
Solution Approach 1:
The matrix in MALDI serves as an intermediary that absorbs laser energy and transfers it gently to analyte molecules through proton transfer mechanisms. This indirect energy transfer allows desorption of labile species without the excessive direct energy deposition that would occur with MeV ion impact, preserving molecular integrity
3Productivity
If conventional quadrupole ion guides are used to transport ions, then ion transport is achieved, but device complexity increases due to multiple electrodes and potential distributions
Solution Approach 1:
The patent extracts and eliminates the DC trapping electrodes from the conventional quadrupole structure, reducing the device to a simpler configuration that achieves ion transport through RF-only operation. This extraction of unnecessary components reduces device complexity while maintaining ion transport functionality
Solution Approach 2:
The patent makes the RF multipole structure perform multiple functions: ion confinement, ion transport, and ion selection. By eliminating dedicated DC trapping electrodes and using the RF fields for multiple purposes, the device achieves multi-functionality with reduced structural 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 enhances the mass spectrometric analysis by reducing fragmentation, improving ion transmission, and achieving higher mass resolving power, enabling the analysis of a broader range of molecular weights, including large and labile species, with improved efficiency and accuracy.
Implementation Method 1
a rectilinear electrode arrangement and a specific potential distribution that creates a homogeneous electrostatic and electrodynamic field
Implementation Method 2
a rectilinear electrode arrangement and a specific potential distribution that creates a homogeneous electrostatic and electrodynamic field
Implementation Method 3
An RF potential is applied between the electrodes and within a given line of electrodes, the potential applied to the electrodes is a linear function of the position of the electrode along the line. The abridged RF multipole field thus formed focuses ions toward the central axis
Implementation Method 4
energy deposition during ionization processes, which leads to fragmentation and loss of molecular weight information
Data Source
Figure 1A
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Figure 2
AI summary
An improved trap-TOF mass spectrometer has a set of electrodes arranged to produce both a quadrupolar RF confining field and a substantially homogeneous dipole field. In operation, ions are first confined by the RF field and then, at a selected time, the RF confining field is discontinued and the dipole field is used to accelerate the ions so as to initiate a TOF MS analysis. The apparatus of the present invention may be used alone or in conjunction with other analyzers to produce mass spectra from analyte ions.