Ammonia Generation Device for GC/CI-MS/MS Safety
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Solution Overview
Problem
The use of compressed ammonia in GC/CI-MS/MS and ICP-MS systems poses safety challenges due to its toxicity and potential for filament carbonization, requiring a safe and controlled method for generating pure ammonia, especially since existing methods like thermal decomposition of ammonium carbonate produce impure ammonia and are not suitable for these applications.
Innovation Solution
A method involving the thermal decomposition of ammonium carbonate with diethanolamine or monoethanolamine in a controlled temperature environment to produce pure ammonia, where the carbon dioxide and water by-products are absorbed, allowing for the regeneration of the amines for repeated use, and the controlled release of ammonia at a stable rate, with optional addition of helium or nitrogen to mitigate vacuum pump issues.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If compressed ammonia gas is used for GC/CI-MS/MS and ICP-MS applications, then high sensitivity and low fragmentation are achieved, but safety hazards and filament carbonization occur
Solution Approach 1:
The patent uses an ammonia-generating device as an intermediary system that produces ammonia on-demand from ammonium carbonate decomposition, eliminating the need to store or handle compressed ammonia gas cylinders. This mediator approach maintains the analytical benefits of ammonia while removing safety hazards associated with compressed gas storage and handling.
Solution Approach 2:
The invention extracts only the necessary component (ammonia) from a stable compound (ammonium carbonate) through controlled thermal decomposition. By taking out ammonia on-demand at the point of use, the system eliminates the need to handle bulk compressed ammonia gas, thereby removing safety hazards while maintaining analytical performance.
2Object-affected harmful factors
If thermal decomposition of ammonium carbonate is used to generate ammonia, then safety hazards are reduced, but ammonia purity deteriorates due to CO2 and H2O by-products
Solution Approach 1:
The patent extracts ammonia selectively from the decomposition products of ammonium carbonate by passing the gas mixture through a series of traps and filters that remove CO2 and H2O by-products. This extraction process isolates pure ammonia from the decomposition mixture, maintaining both safety and purity.
Solution Approach 2:
The invention introduces intermediary substances (desiccants, CO2 traps, and filtering media) between the decomposition reaction and the mass spectrometer. These intermediaries selectively remove impurities (H2O and CO2) while allowing ammonia to pass through, thereby purifying the gas stream without compromising safety.
3Measurement precision
If high concentration ammonia is used for chemical ionization, then sensitivity is improved, but negative effects on vacuum pump fluids and seals increase
Solution Approach 1:
The patent applies partial action by using exactly 1 mL/min of ammonia (the minimum required for optimal chemical ionization) rather than higher concentrations. This partial approach provides sufficient sensitivity while minimizing the harmful effects on vacuum pump fluids and seals. The controlled on-demand generation ensures precise dosage control.
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 generates pure ammonia at a controlled rate, matching the performance of traditional ammonia gas cylinders, reducing safety risks and maintaining instrument integrity by minimizing ammonia's negative effects on vacuum pump fluids and seals, while ensuring consistent analytical results across multiple sample analyses.
Implementation Method 1
heating the reaction vessel to a temperature of 50-60° C. to decompose the ammonium carbonate to form ammonia, carbon dioxide and water
Implementation Method 2
absorbing the carbon dioxide and water by the diethanolamine to form diethanolamine carbonate
Data Source
AI summary
A method of supplying ammonia to a gas chromatography-chemical ionization tandem mass spectrometry (GC/CI-MS/MS) includes the steps of: providing ammonium carbonate and diethanolamine in a reaction vessel; heating the reaction vessel to a temperature of 50-60° C. to decompose the ammonium carbonate to form ammonia, carbon dioxide and water; absorbing the carbon dioxide and water by the diethanolamine to form diethanolamine carbonate; and supplying the ammonia to the GC/CI-MS/MS. Another method of supplying ammonia to a gas chromatography-chemical ionization tandem mass spectrometry (GC/CI-MS/MS) includes the steps of: providing ammonium carbonate and a mixture of monoethanolamine and diethanolamine in a reaction vessel; reacting the ammonium carbonate with the monoethanolamine to form ammonia and monoethanolamine carbonate; and supplying the ammonia to the GC/CI-MS/MS.