Continuous-Beam FTMS with Sequential Field Interrogation
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Solution Overview
Problem
Conventional Fourier transform mass spectrometry (FTMS) systems require lengthy trapping and cooling steps, limiting their analytical duty cycle and resolution, sensitivity, and speed.
Innovation Solution
The method involves passing a continuous ion beam through a quadrupole assembly with radially-confining fields of varying RF and DC voltages to excite ions, converting radial oscillations into axial oscillations, and applying multiple excitation pulses under different field conditions to generate multiple mass spectra, which are then combined for improved resolution and sensitivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional FTMS techniques are used with trapping and cooling steps, then ion oscillations can be measured, but the analytical duty cycle is limited due to lengthy preparation time
Solution Approach 1:
The patent extracts and eliminates the trapping and cooling steps from the conventional FTMS workflow. By using a continuous ion beam through a quadrupole assembly with radially-confining fields, the method removes the time-consuming preparation steps while maintaining the ability to measure ion oscillations and generate mass spectra.
Solution Approach 2:
The patent applies preliminary radial confinement to the continuous ion beam before excitation, establishing stable oscillation conditions without requiring post-ionization trapping and cooling. This preliminary structuring of the ion beam allows immediate measurement upon excitation, eliminating delays.
2Measurement precision
If sequential excitation pulses under different field conditions are applied, then resolution and sensitivity are improved, but the system complexity increases
Solution Approach 1:
The patent employs dynamic adjustment of radial confinement field conditions between sequential excitation pulses. By varying the field parameters (RF amplitude, DC offset) rather than physical configuration, the system achieves multiple mass spectra with different resolutions using the same hardware, reducing complexity compared to multiple fixed instruments.
Solution Approach 2:
The patent changes operational parameters of the radial confinement field (voltage amplitudes, frequencies, DC offsets) to optimize mass spectral resolution for different analytical needs. These parameter adjustments are made through software control of the quadrupole assembly, avoiding hardware complexity while achieving enhanced measurement precision.
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 significantly enhances the analytical duty cycle, resolution, and sensitivity of FTMS by eliminating the need for trapping and cooling steps and allowing for sequential interrogation of the ion beam under different field conditions, resulting in improved mass spectral resolution and dynamic range.
Implementation Method 1
a first radial confinement signal is applied to the quadrupole rod set so as to generate a first field for radially confining at least a first portion of the ions as they pass through the quadrupole rod set
Implementation Method 2
fringing fields in proximity to said output end convert said radial oscillations into axial oscillations as said excited ions exit the quadrupole rod set
Implementation Method 3
a voltage pulse is applied across the quadrupole assembly so as to excite radial oscillations of the first portion of ions at secular frequencies thereof
Implementation Method 4
The axially oscillating ions exiting the quadrupole rod set for the first radial confinement signal generates a first time-varying signal
Data Source
AI summary
Methods and systems for FTMS-based analysis having an improved duty cycle relative to conventional FTMS techniques are provided herein. In various aspects, the methods and systems described herein operate on a continuous ion beam, thereby eliminating the relatively long duration trapping and cooling steps associated with Penning traps or orbitraps of conventional FTMS systems, as well as provide increased resolving power by sequentially interrogating the continuous ion beam under different radially-confining field conditions.