Ion Source Gas Flow Control for Stable Mass Spectrometer Sensitivity
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Solution Overview
Problem
Existing mass spectrometers face sensitivity loss due to variations in atmospheric pressure affecting the ion source, as adjusting gas flow rates to stabilize pressure often deviates from the optimal values required for sensitivity.
Innovation Solution
A mass spectrometer with an ion source and control unit that adjusts the flow rates of gases based on stored measurement conditions, using a pressure adjustment gas to maintain optimal pressure within the ion source chamber, independent of external atmospheric pressure fluctuations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If the flow rate of ionization gas is adjusted to stabilize pressure in the ion source, then pressure stability is improved, but sensitivity of the mass spectrometer deteriorates due to deviation from optimal gas flow rate
Solution Approach 1:
The gas supply system is segmented into two independent channels: one for ionization gas (second gas) and another for pressure control (first gas). This allows independent optimization of each function - the ionization gas flow rate can be maintained at optimal values for sensitivity while the pressure control gas separately manages pressure stability, eliminating the trade-off between the two parameters.
2Stability of the object's composition
If atmospheric pressure variations are compensated by adjusting ionization gas flow rate, then pressure control is improved, but ionization efficiency deteriorates due to non-optimal gas flow conditions
Solution Approach 1:
The system separates pressure control function from ionization function by introducing a dedicated pressure control gas channel. The ionization gas flow rate remains fixed at optimal values for reliable ionization, while atmospheric pressure variations are compensated by adjusting the pressure control gas flow rate independently, thus maintaining both pressure stability and ionization efficiency.
3Device complexity
If a single gas flow rate is used for both ionization and pressure control, then system complexity is reduced, but the ability to maintain optimal performance under varying conditions deteriorates
Solution Approach 1:
The gas supply system is divided into separate channels for ionization gas and pressure control gas, each with independent flow rate control. This segmentation enables the system to adapt to different measurement conditions and atmospheric pressure variations by independently adjusting each gas flow rate according to stored optimal values, significantly improving versatility without excessive complexity increase.
Solution Approach 2:
The system implements dynamic flow rate control for both ionization gas and pressure control gas based on stored optimal values corresponding to different measurement conditions. This allows the system to dynamically adapt to varying sample types, sample solution compositions, and atmospheric pressure conditions, enhancing versatility and performance optimization.
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 maintains sensitivity by ensuring the ion source pressure remains stable, allowing for consistent and robust mass spectrometry performance.
Implementation Method 1
an ion source that ionizes a sample
Implementation Method 2
controls a flow rate of the first gas to suppress a variation in a pressure inside the ion source chamber
Data Source
AI summary
Provided are a mass spectrometer and a method for controlling the same capable of suppressing decrease in sensitivity even where the atmospheric pressure around the mass spectrometer varies. The mass spectrometer includes an ion source, a mass analysis unit, a control unit, and a storage unit. The ion source includes an ion source chamber, an inlet, a first gas introduction port, a second gas introduction port, an outlet, and a gas discharge port. The storage unit stores a table indicating a relationship between a measurement condition and a flow rate of the second gas. The control unit changes the flow rate of the second gas according to the measurement condition on the basis of the table, and controls a flow rate of the first gas to suppress a variation in a pressure inside the ion source chamber.