Mass Spectrometer Ion Signal Deconvolution for Peak Resolution
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Solution Overview
Problem
Time of Flight mass spectrometers face limitations in dynamic range due to dead-time effects and inability to distinguish between single and multiple ion arrivals, leading to inaccurate signal intensity and arrival time measurements, especially at high signal intensities.
Innovation Solution
A method involving the use of an Analogue to Digital Converter to digitize ion detector signals, followed by deconvolution using a point spread function to determine ion arrival times and intensities, employing algorithms like the modified CLEAN algorithm for improved peak resolution and valley separation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If Time to Digital Converter is used to detect ion arrival events, then weak signals can be detected, but dead-time effects prevent recording of subsequent ion arrivals and multiple simultaneous ions cannot be distinguished
Solution Approach 1:
The patent segments the ion detection process into two independent components: Time to Digital Converter for precise timing of weak signals, and Analogue to Digital Converter for accurate intensity measurement. This segmentation allows each converter to operate in its optimal range without the limitations of the other.
Solution Approach 2:
The patent merges the outputs of both TDC and ADC systems by combining the precise arrival time data from TDC with the accurate intensity information from ADC. This combination creates a hybrid detection system that overcomes the individual limitations of each converter type.
2Reliability
If Analogue to Digital Converter is used to digitize ion detector signals, then multiple simultaneous ion arrivals can be recorded, but electronic noise limits the dynamic range
Solution Approach 1:
The patent uses the TDC system as an intermediary to identify and flag ion arrival events. These flagged events are then processed by the ADC system with adjusted sensitivity, allowing the ADC to accurately measure intensity without being overwhelmed by electronic noise from low-intensity signals.
Solution Approach 2:
The system dynamically adjusts the operating parameters of the ADC based on the arrival time information from the TDC. When ion arrivals are detected by the TDC, the ADC operates with optimized thresholds and gain settings to accurately capture the intensity while filtering out electronic noise.
3Reliability
If Analogue to Digital Converter is used, then the analogue width of the signal adds to the width of the ion arrival envelope, but this provides accurate intensity information for multiple ions
Solution Approach 1:
The patent extracts the intensity information from the analogue signal width contribution and separates it from the timing information. By using TDC to provide precise arrival times and ADC to provide intensity measurements, the system removes the confounding effect of analogue width on spectral resolution while preserving the valuable intensity data.
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 peak symmetry, increases mass resolution, and reduces artifacts by accurately separating overlapping ion signals, thereby improving the accuracy of ion arrival time and intensity measurements.
Implementation Method 1
Time of Flight mass spectrometers
Implementation Method 2
signals resulting from ions arriving at an ion detector
Data Source
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AI summary
A method of mass spectrometry is disclosed wherein a signal output from an ion detector is digitised by an Analogue to Digital Converter and is then deconvoluted to determine one or more ion arrival times and one more ion arrival intensities. The process of deconvoluting the ion signal involves determining a point spread function characteristic of an ion arriving at and being detected by the ion detector. A distribution of ion arrival times which produces a best fit to the digitised signal is then determined given that each ion arrival is assumed to produce a response given by the point spread function. A plurality of ion arrival times are then combined to produce a composite ion arrival time-intensity spectrum.