Ion Trap Filling Control via Intermittent Current Sampling
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Solution Overview
Problem
Existing methods for controlling the filling of ion traps in mass spectrometry face challenges with unstable or transient ion sources, leading to inaccurate prediction of ion filling rates and potential overfilling, which can result in space-charge effects and reduced mass resolution.
Innovation Solution
A method involving intermittent detection of ions during the filling process, using sampling intervals shorter than the timescale of ion current variation to accurately monitor and adjust the filling time, ensuring precise control of the ion trap's ion quantity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Extent of automation
If pre-scan methods are used to control ion trap filling, then automation is improved, but measurement precision deteriorates when ion current is rapidly decaying or exhibits beat structure
Solution Approach 1:
The patent implements a feedback mechanism where the actual ion current measured during the analytical scan is compared with the predicted ion current from the pre-scan. The system automatically adjusts the fill time for subsequent scans based on this comparison, correcting for deviations caused by rapidly decaying or beat-structured ion currents. This closed-loop feedback resolves the contradiction by maintaining measurement precision while preserving automation.
Solution Approach 2:
The patent performs a pre-scan measurement before the analytical scan to predict the ion accumulation rate and determine the optimal fill time. This preliminary action provides an initial estimate that is then refined using feedback from the actual ion current measurement during the analytical scan, ensuring accurate control even when ion current characteristics change rapidly.
2Productivity
If ion trap is filled with as many ions as possible, then productivity is improved, but mass resolution deteriorates due to space-charge effects
Solution Approach 1:
The patent dynamically adjusts the ion trap fill time for each analytical scan based on the actual ion current characteristics measured during the previous scan. By continuously adapting the fill time to match the actual ion production rate, the system maximizes ion accumulation while preventing overfilling that would cause space-charge effects, thus maintaining both productivity and mass resolution.
Solution Approach 2:
The patent changes the fill time parameter based on measured ion current characteristics. When ion current is rapidly decaying or exhibits beat structure, the system adjusts the fill time to ensure the ion trap is filled to the optimal level, preventing space-charge effects while maximizing ion accumulation for subsequent analysis.
3Device complexity
If pre-scan reading is used to determine fill time, then device complexity is reduced, but reliability deteriorates when ion current is unstable or transient
Solution Approach 1:
The patent uses feedback from the actual ion current measured during the analytical scan to correct the fill time determination. When ion current is unstable or transient, the system compares the predicted fill time from the pre-scan with the actual ion current characteristics and adjusts subsequent fill times accordingly, maintaining reliability without significantly increasing device complexity.
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 allows for more accurate control of ion trap filling, maximizing ion availability for analysis while minimizing space-charge effects, even with unstable ion sources, by dynamically adjusting to variations in ion current.
Implementation Method 1
detecting at an ion detector at least some ions from the source of ions during a plurality of distinct sampling time intervals interspersed within the transmission time period
Data Source
AI summary
A method for controlling the filling of an ion trap with a predetermined quantity of ions. The method comprises generating an ion current by transmitting ions along an ion path to an ion trap, such that ions are accumulated in the ion trap over a transmission time period, wherein the magnitude of the ion current varies in time. The method further comprises detecting at an ion detector at least some ions from the source of ions during a plurality of distinct sampling time intervals interspersed within the transmission time period, and setting the duration of the transmission time period based on the detection of ions at the ion detector. The time difference between the start of a sampling time interval and the start of an immediately subsequent sampling time interval is less than a timescale for variation of the magnitude of the ion current. A controller for controlling the filling of an ion trap with a predetermined quantity of ions and a mass spectrometer comprising the controller is also described.