Miniature Ion Source Fixed Geometry Gas Flow Optimization
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Solution Overview
Problem
Conventional miniature mass spectrometers face challenges with complex ion source configurations, high user interaction requirements, and sensitivity issues due to buffer compounds and gaseous ammonia, especially at higher liquid flow rates and pressures.
Innovation Solution
A fixed orientation and gas flow rate configuration for the Electrospray ion source with a tri-axial arrangement, including a desolvation gas supply tube surrounding the capillary tubes, and specific gas flow rates (analyte liquid >200 µL/min, desolvation gas 400-1200 L/hr, nebuliser gas 80-150 L/hr, cone gas 40-80 L/hr) to optimize ion generation and transfer, reducing user interaction and sensitivity issues.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If conventional Electrospray ion sources are used with many degrees of freedom for tuning, then the ion source can be optimized for various compounds and circumstances, but the device complexity increases and makes it difficult for unskilled users to operate
Solution Approach 1:
The patent applies parameter changes by fixing specific parameters (liquid flow rate at 200-1000 μL/min, gas flow rates, temperatures) to create a simplified operation mode while maintaining adaptability through the ability to change these parameters when needed. This resolves the contradiction by providing both versatility and ease of operation.
Solution Approach 2:
The ion source is designed to automatically optimize performance within the fixed parameter ranges without requiring user intervention for tuning. The system self-adjusts to provide optimal ionization for various compounds within the predetermined parameter constraints, making it user-friendly while maintaining versatility.
2Productivity
If higher liquid flow rates are used in the ion source, then the productivity increases, but sensitivity issues arise due to buffer compounds and gaseous ammonia
Solution Approach 1:
The patent changes the liquid flow rate parameter to a higher range (200-1000 μL/min) and compensates for sensitivity issues by optimizing other parameters including gas flow rates and temperatures. This resolves the contradiction by maintaining high productivity while preserving sensitivity through coordinated parameter optimization.
Solution Approach 2:
The patent introduces optimized gas flows (desolvation gas, nebulizer gas, cone gas) as intermediaries that mediate between the high liquid flow rate and the detection system. These gas flows help remove buffer compounds and gaseous ammonia, preventing them from interfering with sensitivity while allowing high productivity.
3Volume of moving object
If a miniature mass spectrometer is used with reduced size, then the portability improves, but the vacuum system complexity increases due to multiple diaphragm pumps being required
Solution Approach 1:
The patent merges the vacuum pumping functions by using a single diaphragm pump to back both the first and second turbomolecular pumps. This consolidation reduces the number of separate pump components while maintaining the necessary vacuum levels for the miniature mass spectrometer, thereby reducing overall system complexity.
Solution Approach 2:
The single diaphragm pump is designed to perform multiple functions: backing the first turbomolecular pump for the atmospheric pressure interface and backing the second turbomolecular pump for the ion guide. This multi-functionality reduces component count and simplifies the vacuum system while maintaining miniaturization benefits.
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
The configuration enhances ion source robustness, minimizes signal loss due to buffer compounds, and maintains high sensitivity, making the mass spectrometer more user-friendly and efficient for inexperienced operators.
Implementation Method 1
a heater arranged and adapted to heat the desolvation gas to a temperature ≥ 100° C
Implementation Method 2
a third device arranged and adapted to supply a desolvation gas via the desolvation gas supply tube at a flow rate in the range 400-1200 L/hr
Implementation Method 3
an Electrospray ion source comprising a first capillary tube having an outlet and having a second longitudinal axis and a second capillary tube which surrounds the first capillary tube
Data Source
Figure 1
Figure 2a
Figure 2b
AI summary
A mass spectrometer is disclosed comprising an atmospheric pressure interface comprising a gas cone 6 having an inlet aperture, wherein the gas cone 6 has a first longitudinal axis arranged along an x-axis and an Electrospray ion source comprising a first capillary tube 2 having an outlet and having a second longitudinal axis and a second capillary tube 3 which surrounds the first capillary tube 2. The mass spectrometer further comprises a desolvation gas supply tube and a first device arranged and adapted to supply an analyte liquid via the first capillary tube 2 so that the liquid exits the outlet of the first capillary tube 2 at a flow rate > 200 μL/min. The mass spectrometer further comprises a second device arranged and adapted to supply a nebuliser gas via the second capillary tube 3 at a flow rate in the range 80-150 L/hr, wherein an outlet of the first capillary tube 2 is arranged at a distance x mm along the x-axis as measured from the centre of the gas cone inlet aperture, a distance y mm along a y-axis as measured from the centre of the gas cone inlet aperture and a distance z mm along a z-axis as measured from the centre of the gas cone inlet aperture. The x-axis, the y-axis and the z-axis are mutually orthogonal. The desolvation gas supply tube surrounds the second capillary tube 3 and the mass spectrometer further comprises a third device arranged and adapted to supply a desolvation gas via the desolvation gas supply tube at a flow rate in the range 400-1200 L/hr, a heater 4 arranged and adapted to heat the desolvation gas to a temperature≥ 100° C and a fourth device arranged and adapted to supply a cone gas to the gas cone 6 at a flow rate in the range 40-80 L/hr and wherein x is in the range 2.0-5.0 mm and wherein the ratio z/x is in the range 1-5:1.