Sample Chamber Evacuation for Mass Spectrometer Sensitivity
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Solution Overview
Problem
Existing chemical analysis instruments, such as mass spectrometers, face challenges in detecting explosives with low volatility indices due to their low vapor emission, which results in reduced sensitivity and longer analysis times when using miniature instruments operating at lower pressures.
Innovation Solution
A method involving a sample collection system where a collector is inserted into a sample chamber, evacuated to reduce internal pressure, and then heated to release the sample, increasing the sample concentration for detection by a mass spectrometer, thereby enhancing sensitivity and reducing analysis time.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a miniature mass spectrometer operates at lower pressures to detect trace chemicals, then the detection sensitivity should improve, but the analysis time increases and the instrument becomes less effective for low volatility substances
Solution Approach 1:
The sample chamber is evacuated to reduce internal pressure before the sample is introduced and analyzed. This preliminary evacuation creates optimal conditions for detection by removing competing gas molecules that would interfere with the mass spectrometer's ability to detect trace chemicals, thereby improving sensitivity without requiring prolonged analysis time
Solution Approach 2:
The pressure parameter of the sample chamber is dynamically changed by evacuating it to a reduced pressure state before analysis. This parameter change enhances the mass spectrometer's detection capability by reducing background gas interference, allowing rapid detection of low volatility substances without the time penalty associated with continuous low-pressure operation
2Quantity of substance
If the collector is heated to release the sample, then the sample concentration increases for better detection, but heat requirements and energy consumption increase
Solution Approach 1:
The sample chamber is evacuated to create a vacuum or reduced pressure environment before sample introduction. This inert environment prevents sample loss through adsorption onto chamber walls and reduces the amount of heat required to vaporize and transport the sample, as there is no atmospheric pressure resisting the phase change
Solution Approach 2:
The sample undergoes phase transition from adsorbed state to vapor phase within the evacuated chamber. The reduced pressure environment facilitates this phase transition at lower temperatures, reducing the energy required for heating while still achieving sufficient sample concentration for detection
3Quantity of substance
If the sample chamber is evacuated before sample introduction, then the effective concentration of the sample increases, but the device complexity increases due to additional vacuum components
Solution Approach 1:
The vacuum pump is integrated with the mass spectrometer system, sharing common components and control systems. The sample chamber evacuation mechanism is combined with the instrument's existing vacuum architecture, eliminating the need for separate vacuum systems and reducing overall device complexity while still achieving the concentration enhancement benefit
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 significantly increases the effective concentration of the sample, improves detection accuracy, and reduces contamination and heat requirements, allowing for rapid detection of explosives at extremely low concentrations without prolonging analysis time.
Implementation Method 1
evacuating the sample chamber using the vacuum pump to reduce an internal pressure of the sample chamber to a level less than atmospheric pressure
Implementation Method 2
heating the collector to release the sample from the collector
Implementation Method 3
heating the collector to release the sample from the collector into the evacuated sample chamber
Data Source
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AI summary
In one general aspect, a sample is transferred into a mass spectrometer (150) by capturing a sample on a collector (125), inserting the collector (125) into a sample chamber (110) coupled to the mass spectrometer (150) and a vacuum pump (342, 344), evacuating the sample chamber (110) using the vacuum pump (342, 344) to reduce an internal pressure of the sample chamber (110) to a level less than atmospheric pressure, heating the collector (125) to release the sample from the collector, and introducing the sample into the mass spectrometer (150) from the evacuated sample chamber (110).