Integrated DMS-MS Apparatus for Ion Transmission and Resolution
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Solution Overview
Problem
Current differential ion mobility spectrometry (DMS) devices are limited by operating at ambient or sub-ambient pressures, leading to low ion transmission efficiency, restricted sampling capacity, and poor resolution, especially when analyzing complex samples or high-flow rate applications, due to fixed flow rates and limited E/N ratios.
Innovation Solution
Integrating a DMS device within the initial pumping stage of a mass spectrometer, utilizing specific pressure and waveform frequency ranges (2kPa to 40kPa and 20kHz to 25MHz) to enhance resolving power and ion transmission, and employing a multipole DMS with a dipole field and higher-order fields for radial focusing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If DMS device operates at ambient or sub-ambient pressure, then ion mobility separation can be achieved, but ion transmission efficiency is low and sampling capacity is restricted
Solution Approach 1:
The patent changes the operating pressure parameter from ambient/sub-ambient to intermediate pressure range (1-1000 mbar), and adjusts waveform frequency to 20kHz-25MHz, extending E/N ratios to 10^-20 to 10^-18 Td. These parameter changes optimize both ion mobility separation and transmission efficiency simultaneously
Solution Approach 2:
The patent employs dynamic adjustment of asymmetric waveform frequency and amplitude to optimize ion transmission across different pressure conditions. The system dynamically adapts operating parameters to maintain high transmission efficiency while preserving separation capability
2Device complexity
If fixed flow rate is used in DMS device, then device structure is simplified, but resolving power is poor especially for complex samples
Solution Approach 1:
The patent implements variable flow rate capability through adjustable gas flow means, allowing the system to optimize flow conditions for different sample complexities. This dynamic adjustment enhances resolving power without significantly increasing device complexity
Solution Approach 2:
The patent changes the flow rate parameter from fixed to variable, and extends E/N ratios to broader ranges (10^-20 to 10^-18 Td), enabling optimized resolution for complex samples while maintaining reasonable device structure
3Productivity
If DMS device is integrated within mass spectrometer vacuum enclosure, then ion transmission is improved, but device complexity increases
Solution Approach 1:
The patent merges the DMS device with the mass spectrometer vacuum enclosure, integrating two functions into one system. This combination improves ion transmission by eliminating interface losses while the shared vacuum infrastructure minimizes the increase in overall device complexity
Solution Approach 2:
The integrated design allows the vacuum enclosure to serve dual purposes: housing both the DMS separation region and the mass analysis region. This multi-functionality approach improves transmission efficiency without proportionally increasing device complexity
4Adaptability or versatility
If ambient pressure IMS is used, then atmospheric pressure ionization sources can be utilized, but ion beam diffusion causes low sampling efficiency
Solution Approach 1:
The patent changes the pressure parameter from ambient to intermediate pressure (1-1000 mbar), which reduces ion beam diffusion while maintaining compatibility with atmospheric pressure ionization sources through the intermediate pressure interface
Solution Approach 2:
The patent employs dynamic pressure control in the intermediate pressure region to optimize the balance between ionization source compatibility and ion beam focusing, adjusting pressure to minimize diffusion while maintaining source versatility
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 configuration extends the range of E/N values, improves ion transmission, and achieves better resolving power, enabling more efficient analysis of complex samples and high-flow rate applications while maintaining sensitivity and resolution.
Implementation Method 1
Ion mobility is defined as the ratio of the average drift velocity of an ion group injected into the IMS cell over the applied electric field, K=u AV /E. Therefore, the drift time of an ion through a given length is determined by the applied electric field and the mobility
Implementation Method 2
differential mobility spectrometry (DMS), also known as field asymmetric ion mobility spectrometry (FAIMS), relies on the dependency of the ion mobility, K, on the applied electric field and number gas density, E/N
Implementation Method 3
an apparatus includes gas flow means for establishing a flow of gas into the first vacuum region so as to provide a gas medium for the differential ion mobility means
Implementation Method 4
pumping means configured to provide a pressure in the second vacuum region that is lower than the pressure in the first vacuum region
Implementation Method 5
employing a multipole DMS with a dipole field and higher-order fields for radial focusing
Data Source
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AI summary
The present invention is concerned with an ion analysis apparatus for conducting differential ion mobility analysis and mass analysis. In embodiments, the apparatus comprises a differential ion mobility device in a vacuum enclosure of a mass spectrometer, located prior to the mass analyser, wherein the pumping system of the apparatus is configure to provide an operating pressure of 0.005kPa to 4OkPa for the differential ion mobility device, and wherein the apparatus includes a digital asymmetric waveform generator that provides a waveform of frequency of 5OkHz to 25MHz. Examples demonstrate excellent resolving power and ion transmission. The ion mobility device can be a multipole, for example a 12-pole and radial ion focusing can be achieved by applying a quadrupole field to the device in addition to a dipole field.