Bubble Plasma Ionisation Probe for Liquid Analysis
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Solution Overview
Problem
Conventional mass spectrometry techniques, such as ESI-MS, are inconvenient and destructive, requiring sample preparation and removal, which is not suitable for rapid and direct analysis of analytes in liquid solutions, especially in applications where sample loss is unacceptable, like microfluidic processing.
Innovation Solution
A plasma probe system with a gas bubble attached to co-axial conduits submerged in the liquid generates ions at the gas-liquid interface, allowing for in situ ionization and analysis without sample preparation or removal, using a feedback loop to maintain a stable bubble size and prevent liquid entry into the mass spectrometer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If electrospray ionisation is used to analyse liquid solutions, then ionisation can be achieved, but sample preparation and removal are required which causes delays and sample loss
Solution Approach 1:
The invention extracts only the essential function of ionisation from the complex ESI process by using a plasma source that can ionise analytes directly in the liquid phase or at the gas-liquid interface, eliminating the need for capillary sampling, spray formation, and solvent evaporation steps required in conventional ESI-MS
Solution Approach 2:
The patent introduces a plasma as an intermediary between the liquid sample and the mass spectrometer. The plasma provides a mechanism for direct ionisation of analytes in liquid or at the gas-liquid interface, serving as a mediator that enables mass spectrometric analysis without requiring the sample to be in a form suitable for conventional ESI injection
2Ease of operation
If ESI-MS is used for liquid analysis, then ionisation can be achieved, but multiple processing steps and chemical consumables are required
Solution Approach 1:
The invention extracts and eliminates the complex sample preparation steps (filtration, solvent exchange, addition of chemical modifiers) from the analysis workflow by using plasma ionisation that can handle diverse liquid matrices directly or with minimal preparation
Solution Approach 2:
The plasma source provides a universal ionisation mechanism that can analyse diverse analytes in various liquid matrices without requiring specific solvent systems or chemical modifiers, making the technique applicable to a wide range of samples including aqueous solutions, organic solvents, and complex biological fluids
3Measurement precision
If ESI-MS is used for liquid analysis, then ionisation can be achieved, but the liquid sample is consumed and cannot be recovered
Solution Approach 1:
The plasma acts as an intermediary that enables analysis without direct contact between the liquid sample and the mass spectrometer vacuum system. The gas-liquid interface or bubble configuration allows ionisation to occur while the bulk liquid remains in the original container, enabling non-destructive monitoring
4Productivity
If ambient ionisation is performed on liquid surfaces, then rapid analysis can be achieved, but the analysis may not be representative of bulk liquid due to surface effects
Solution Approach 1:
The patent uses gas flow to create a bubble attached to the probe tip that is submerged in or in contact with the bulk liquid. The bubble configuration ensures that the plasma ionises analytes from the bulk liquid phase rather than from a free surface, eliminating surface effects such as atmospheric oxidation, thermal gradients, and phase separation while maintaining rapid analysis capability
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 rapid, non-destructive analysis of bulk liquids with no delays or sample loss, providing a chemical profile representative of the liquid, suitable for pressurized and flowing samples, and is compatible with continuous monitoring.
Implementation Method 1
a plasma to generate gas phase ions and subsequently analysing said ions with a mass spectrometer
Implementation Method 2
The gas pressure or flow rate is adjusted such that a gas bubble forms at the open end of the first conduit, which prevents liquid being drawn into the mass spectrometer
Data Source
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AI summary
Bubble plasma ionisation probe for analysing liquids by mass spectrometry A means of a detecting analytes dissolved in a liquid by mass spectrometry is described. Gas flows from a source through a first conduit 105 and thereafter through a coaxial second conduit 103 that also serves as the inlet to the mass spectrometer 102. The coaxial arrangement of conduits is submerged in the liquid to be analysed 301. Using a feedback loop, the gas pressure is adjusted and controlled such that an attached bubble 302 forms at the open end of the first conduit 105. A plasma 305 is provided in the bubble. The plasma is preferably generated by a dielectric barrier discharge between a collar electrode 107 and mass spectrometer inlet 103. Analytes dissolved in the liquid are both desorbed form the gas-liquid interface and ionised by the action of the plasma. Ions formed in this way become entrained in the gas flow and are consequently transferred to the mass spectrometer, where they are analysed.