Histogramming Ion Areas on Peak Detecting ADCs
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Solution Overview
Problem
Existing peak detecting analogue to digital converters in mass spectrometry systems face issues with saturation effects leading to inaccurate intensity and time measurements, and struggle to distinguish between closely spaced ion response signals, resulting in reduced resolution and accuracy.
Innovation Solution
A method of mass spectrometry that involves digitizing ion detector signals, detecting peaks, and determining their areas and intensities, with thresholds set to filter out signals indicative of simultaneous ion arrivals, allowing only signals within a specific range to be histogrammed, thereby improving resolution and accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If peak detecting ADC is used to enhance dynamic range and mass accuracy, then measurement performance is improved, but saturation effects cause loss of accurate intensity and time measurements when vertical range is exceeded
Solution Approach 1:
The patent segments the ion detection process into multiple ADC units, each handling a specific vertical range segment. When one ADC saturates, other ADCs continue to provide valid measurements for that ion, ensuring continuous accurate intensity and time measurements across the full dynamic range without loss of measurement reliability.
Solution Approach 2:
The patent introduces a control system that acts as an intermediary between the ADCs and the data processing system. This control system monitors the output of multiple ADCs, identifies which ADCs are saturated for each ion event, and selectively uses only the non-saturated ADC measurements, thereby eliminating saturation effects from the final intensity and time measurements.
2Measurement precision
If peak detection process is used to convert ion peaks to intensity and arrival time values, then performance is improved relative to height based approaches, but the system is ultimately limited by saturation effects
Solution Approach 1:
The patent divides the detection system into multiple ADC segments operating in parallel, each with its own vertical range. This segmentation allows the system to maintain reliable arrival time measurements even when individual ADCs saturate, as other ADCs in the segmented system continue to provide valid timing data.
Solution Approach 2:
The control system implements feedback by continuously monitoring the output signals from all ADCs to detect saturation conditions. When saturation is detected in one or more ADCs, the control system adjusts which ADC outputs are used for peak detection, ensuring that only non-saturated measurements contribute to the final arrival time and intensity values, thereby maintaining measurement reliability.
3Measurement precision
If ion signals exceed the vertical range of the ADC, then saturation effects occur causing time measurement shifts, but increasing ADC range increases complexity and cost
Solution Approach 1:
Rather than using a single high-range ADC that would be complex and expensive, the patent segments the measurement function across multiple lower-range ADCs. Each ADC handles a portion of the dynamic range, and through coordinated operation controlled by a control system, they collectively provide accurate time measurements across the full range without requiring any single ADC to have excessive complexity.
Solution Approach 2:
The patent makes multiple ADCs perform the same function (time and intensity measurement) simultaneously, with each ADC serving as a backup and supplement to the others. This multi-functionality approach allows the system to maintain measurement accuracy without relying on a single complex high-range ADC, thereby reducing overall device complexity while improving reliability.
4Measurement precision
If the ion response profiles are comparable with or greater than the analyser arrival time distribution, then the peak detection process cannot distinguish between multiple closely spaced ion arrival events, but using multiple ADCs increases system complexity
Solution Approach 1:
The patent segments the signal processing function across multiple ADCs, allowing simultaneous analysis of different temporal segments of ion arrivals. This segmentation enables the system to resolve multiple closely spaced events by distributing their detection across different ADC channels, improving resolution without requiring a single overly complex processing system.
Solution Approach 2:
The patent employs more ADCs than the minimum theoretically required, creating an excessive measurement capacity that provides redundant information about ion arrivals. This partial redundancy allows the control system to cross-validate measurements and distinguish between single and multiple ion arrivals more effectively, improving resolution while managing complexity through selective use of ADC outputs.
Data Source
AI summary
A method of mass spectrometry is disclosed comprising digitising a first signal output from an ion detector to produce a first digitised signal, detecting one or more peaks in the first digitised signal and determining a first area S0 or a first intensity I0 of the one or more peaks and a first arrival time T0 of the one or more peaks thereby forming a first list of data pairs and determining whether or not the first area S0 or the first intensity I0 exceeds a first threshold area Smax or a first threshold intensity Imax. The first threshold area Smax and the first threshold intensity Imax correspond respectively to a peak area and a peak intensity indicative of substantially simultaneous arrival of two ions which the ion detector is unable to resolve. If it is determined that the first area S0 or the first intensity I0 does not exceed the first threshold area Smax or the first threshold intensity I0 then the method further comprises including the first area S0 or the first intensity I0 and/or the first arrival time T0 or data derived from the first area S0 or the first intensity I0 and/or the first arrival time T0 in a first histogram.