Ion Isolation Waveform Amplitude Scaling
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current methods for ion isolation in mass spectrometry, particularly in radio frequency ion traps, face challenges in simultaneously ejecting unwanted ions across a range of mass-to-charge ratios in a consistent timeframe, leading to irregular isolation efficiency and complications when multiple precursors are selected.
Innovation Solution
A mass spectrometer system with a radio frequency ion trap and a controller that applies a waveform with a flat frequency profile and time domain amplitude gain, determined by characterizing the amplitude versus mass-to-charge ratio, to eject unwanted ions at multiple frequencies in a similar amount of time, using calibrant ions to identify the required amplitude and frequency profile for optimal ion isolation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a broadband supplementary ac waveform with energy at unwanted ion frequencies is applied for ion isolation, then unwanted ions are ejected from the ion trap, but the ejection time varies significantly across different mass-to-charge ratios leading to irregular isolation efficiency
Solution Approach 1:
The patent applies parameter changes by adjusting the amplitude of the supplementary ac waveform as a function of frequency. Specifically, the waveform amplitude is scaled such that lower frequency components (corresponding to higher m/z ions) have reduced amplitude compared to higher frequency components. This frequency-dependent amplitude scaling compensates for the mass-to-charge ratio dependence of ion oscillation frequencies, enabling all unwanted ions to be ejected in the same amount of time regardless of their m/z values.
2Productivity
If multiple precursor ions are selected for simultaneous isolation, then the analysis throughput is improved, but the waveform frequency response becomes complex requiring precise amplitude scaling across multiple frequencies
Solution Approach 1:
The patent applies local quality by creating notches in the waveform frequency response at specific frequencies corresponding to each precursor ion to be isolated. Each notch represents a localized frequency region where the waveform amplitude is reduced or eliminated. This allows multiple precursor ions at different m/z ratios to be simultaneously isolated by applying a single composite waveform with multiple targeted notches, rather than requiring separate waveforms for each precursor.
Solution Approach 2:
The patent achieves universality by developing a single broadband supplementary ac waveform that can simultaneously perform ion isolation for multiple precursor ions across a wide mass-to-charge ratio range. The waveform is designed with a universal frequency profile that includes notches at multiple frequencies and amplitude scaling across the entire frequency spectrum, enabling one waveform to replace multiple specialized waveforms.
3Speed
If the waveform amplitude is increased to eject all unwanted ions simultaneously, then isolation speed is improved, but precursor ions may also be affected and ejected reducing isolation specificity
Solution Approach 1:
The patent applies partial action by designing the supplementary ac waveform to provide excitation energy only at specific frequency ranges corresponding to unwanted ions, while deliberately creating notches (zero or minimal amplitude regions) at frequencies corresponding to precursor ions. This selective frequency targeting ensures that the waveform amplitude is sufficient to eject unwanted ions rapidly, while simultaneously protecting precursor ions from ejection by excluding energy at their oscillation frequencies.
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 ensures efficient and simultaneous ejection of unwanted ions across a range of frequencies, optimizing isolation efficiency and simplifying waveform amplitude scaling, thereby improving the accuracy and reliability of ion isolation in mass spectrometry.
Implementation Method 1
a radio frequency ion trap
Implementation Method 2
The broadband supplementary ac waveforms can have a frequency profile containing energy at the oscillation frequencies of the unwanted/interfering ions
Data Source
Figure 1
Figure 2a~2b
Figure 3
AI summary
A mass spectrometer includes a radio frequency ion trap and a controller. The controller is configured to cause an ion population to be injected into the radio frequency ion trap and supply an isolation waveform to the radio frequency ion trap. The isolation waveform has at least one notch at a target mass-to-charge ratio and a frequency profile determined to eject unwanted ions at a plurality of frequencies in a substantially similar amount of time.