Ion Trap Charge Increase for Low-Charge Ion Dissociation
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Solution Overview
Problem
Current ion dissociation methods, such as ETD and ECD, have low dissociation efficiency for ions with a low number of charges, limiting the structural analysis of biopolymer compounds, and existing techniques to increase charge numbers are inefficient due to excessive energy transfer and ion escape issues in magnetic confinement ion traps.
Innovation Solution
A quadrupole ion trap with an electron irradiator injecting electrons of at least 30 eV is used to increase the charge number of precursor ions, combined with a dissociation promoter like HAD, ECD, or ETD, to enhance dissociation efficiency, while maintaining ion stability through higher virtual potential and cooling gas pressure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If ETD or ECD methods are used for ion dissociation, then bond-specific fragmentation and structural analysis capability are improved, but dissociation efficiency for ions with low charge numbers deteriorates
Solution Approach 1:
The patent changes the charge number parameter of the precursor ion by introducing a charge increase step before dissociation. This allows the same dissociation method (ETD/ECD) to work efficiently on ions with increased charge numbers, thereby resolving the contradiction between maintaining bond-specific fragmentation capability and improving dissociation efficiency for originally low-charge ions
2Quantity of substance
If magnetic confinement ion trap is used to increase charge number, then ion confinement is achieved, but excessive energy transfer and ion escape occur
Solution Approach 1:
The patent replaces magnetic confinement with electric field-based confinement in a quadrupole ion trap. This substitution allows for better control of ion energy and prevents both excessive energy transfer and ion escape, while still enabling effective charge number increase through electron irradiation
3Productivity
If electron irradiation is applied to increase charge number, then dissociation efficiency is improved, but ion stability deteriorates due to excessive energy
Solution Approach 1:
The patent applies electron irradiation to increase the charge number of ions before the dissociation step. This preliminary charge increase enables subsequent dissociation to proceed efficiently while maintaining ion stability, as the ions are now in a charge state that is optimized for the dissociation process
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 approach significantly improves dissociation efficiency for ions with low initial charge numbers, enabling accurate structural analysis of biopolymer compounds by increasing the number of charges and internal energy of precursor ions, leading to more informative product ions for mass spectrometry.
Implementation Method 1
a quadrupole ion trap configured to capture an ion derived from a sample component, by an effect of a radio-frequency electric field
Implementation Method 2
an electron irradiator configured to inject an electron having an energy equal to or higher than 30 eV to a target ion captured for dissociation within the ion trap
Implementation Method 3
the most commonly used technique for dissociating an ion having a high-molecular weight in such a mass spectrometer is the collision induced dissociation (CID) method which induces the dissociation of an ion by resonantly oscillating the ion by the effect of an electric field to make the ion collide with argon or similar gas
Implementation Method 4
the HAD method is a method which induces the dissociation of an ion by attaching hydrogen radical (=hydrogen atom) to the ion
Implementation Method 5
a time-of-flight mass separator configured to separate product ions generated by dissociation according to mass-to-charge ratios
Implementation Method 6
an ion detector configured to detect the separated ions
Data Source
AI summary
After a precursor ion has been captured within an ion trap (2), electrons having a high energy equal to or higher than 30 eV are introduced from an electron irradiator (7) into the ion trap (2) to increase the number of charges of the ion through an interaction between the electrons and the ion. Hydrogen radicals are subsequently introduced from a hydrogen radical irradiator (5) into the ion trap (2) to dissociate the ion by a hydrogen-attachment dissociation (HAD) method. The larger the number of charges of the ion is, the higher the dissociation efficiency by the HAD method becomes. Therefore, for example, even in the case of using an ion source in which most of the generated ions are singly charged ions as in a MALDI ion source, the dissociation efficiency can be improved by increasing the number of charges of the precursor ion within the ion trap (2).