Ion Population Attenuation for Mass Spectrometer Dynamic Range
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Solution Overview
Problem
Mass spectrometers face challenges in analyzing complex samples with wide dynamic ranges, as they often require accommodating the most abundant species, leading to limited detection of less abundant components due to dynamic range limitations.
Innovation Solution
A method and apparatus that selectively attenuate relatively abundant ion species and adjust the total ion current to optimize the ion signal within the detector's dynamic range, using ion-optical devices such as mass filters, ion traps, and Dynamic Range Enhancement lenses to control the ion population and detector gain.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the mass analyser accommodates the most abundant species to cover the wide dynamic range of complex samples, then the dynamic range of the analyser is utilized, but the detection of less abundant components is limited
Solution Approach 1:
The ion population is segmented into different groups based on abundance levels. The method selectively attenuates relatively abundant ion species while allowing less abundant species to pass through, effectively dividing the ion population into attenuated and non-attenuated segments that can be detected with appropriate dynamic range
Solution Approach 2:
Different quality control is applied to different parts of the ion population. Relatively abundant species undergo selective attenuation to reduce their signal intensity, while less abundant species are preserved without attenuation, allowing each group to be optimized for detection within the detector's dynamic range
2Measurement precision
If selective attenuation of abundant ion species is applied, then the dynamic range is expanded for detecting less abundant species, but the device complexity increases
Solution Approach 1:
The ion-optical devices are configured to perform multiple functions: they serve as mass analyzers for separation and as selective attenuation devices for abundance-based modulation. This multi-functionality reduces the need for separate dedicated attenuation devices, thereby managing system complexity
Solution Approach 2:
The method employs feedback control where the detection of abundant species triggers automatic attenuation, and the total ion current monitoring feeds back to adjust the attenuation level. This closed-loop feedback system automates the complex coordination of multiple ion-optical devices, reducing operational complexity
3Reliability
If the total ion current is adjusted to optimize detector signal, then the detector operates within dynamic range, but the ion current optimization process adds complexity
Solution Approach 1:
The system performs self-adjustment of total ion current through automatic feedback mechanisms. The total ion current monitor continuously measures the ion current and automatically adjusts the ion source or attenuation parameters to maintain optimal current levels, eliminating the need for manual optimization and reducing operational complexity
Data Source
AI summary
A method of mass spectrometry is disclosed wherein one or more relatively abundant or intense species of ions in a first population of ions are selectively attenuated so as to form a second population of ions. The total ion current of the second population of ions is then adjusted so that the ion current corresponding to ions which are onwardly transmitted to a mass analyser comprising an ion detector is within the dynamic range of the ion detector.