Atmospheric Pressure Ionization Using Argon Dark Discharge
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Solution Overview
Problem
Current atmospheric pressure ionization methods using helium or nitrogen gases face challenges such as excessive by-product generation, high operational costs, vacuum system damage, and difficulty in identifying sample substances due to high energy ionization and complex excitation reactions, as well as the need for high voltages that limit device usability.
Innovation Solution
An atmospheric pressure ionization method utilizing argon gas with a needle electrode having a two-sheeted hyperboloid tip end and applying a dark discharge voltage of 1.8 kV or more to generate excited argon gas with 15.6 eV energy, which reduces by-product generation and allows for efficient protonated and deprotonated molecule detection without requiring high voltages or specialized vacuum systems.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If helium gas is used as the inert gas for atmospheric pressure ionization, then high ionization energy (19.8 eV) enables effective sample ionization, but excessive by-products are generated and vacuum system performance deteriorates
Solution Approach 1:
The patent changes the key parameter from helium gas (19.8 eV) to argon gas (15.7 eV), adjusting the ionization energy to an optimal level that provides sufficient ionization capability while reducing excess energy that causes by-product formation. This parameter change resolves the contradiction by finding a balanced value that satisfies both ionization effectiveness and by-product reduction requirements.
2Power
If helium gas is used as the inert gas, then effective ionization is achieved, but specialized vacuum pumping systems are required increasing device complexity and cost
Solution Approach 1:
The patent replaces helium gas with argon gas, which is abundant, inexpensive, and can be easily pumped by conventional vacuum systems. This substitution eliminates the need for specialized vacuum pumping systems, reducing device complexity and operational costs while maintaining effective ionization capability through argon's suitable energy level (15.7 eV).
3Quantity of substance
If high voltage is applied to cause discharge for ionization, then sufficient ion intensity is achieved, but device usability is limited and operational complexity increases
Solution Approach 1:
The patent changes the gas type from helium to argon, which has a lower ionization energy (15.7 eV vs 19.8 eV). This parameter change allows discharge to occur at lower voltages while still achieving sufficient ion intensity for mass spectrometry, thereby improving device usability and reducing operational complexity without sacrificing ionization effectiveness.
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 method enables efficient and cost-effective ionization of samples with reduced by-product generation, longer device lifespan, and the ability to analyze larger samples without the need for specialized vacuum systems, while maintaining high ion intensity and accuracy in mass spectrometry.
Implementation Method 1
applying a voltage of 1.8 kV or more to the needle electrode from the voltage generation unit to generate a dark discharge
Implementation Method 2
exciting the argon gas with a dark discharge current
Implementation Method 3
when a protonated molecule generation reaction and/or a deprotonated molecule generation reaction of the sample using a penning ionization reaction (12.6 eV) of a water molecule as a starting point is effected
Data Source
AI summary
An atmospheric pressure ionization method uses: a gas flow passage control unit (26) and a gas outlet nozzle (24) configured to jet argon gas to an atmospheric atmosphere; a needle electrode (19) arranged between an outlet port of the gas outlet nozzle (24) and an introduction port of an ion introduction pipe (6) that includes a tip end portion formed into a two-sheeted hyperboloid of revolution having a radius of curvature of 1 μm or more and less than 30 μm; a needle electrode support mechanism (20); and an electric power generation unit (22) configured to apply a voltage to the needle electrode (19). The atmospheric pressure ionization method includes: applying a voltage of 1.8 kV or more to the needle electrode (19) from the voltage generation unit (22) to generate a dark discharge; exciting the argon gas with the dark current; and causing the excited argon gas and the sample to react with each other, to thereby ionize the sample.