Mass Spectrometry Using Adduct Ions for Accurate Precursor Mass
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Solution Overview
Problem
The existing radical attachment dissociation methods in mass spectrometry generate only a few percent of fragment ions, requiring high detector gain which leads to saturation of precursor ion intensity, causing errors in determining the accurate mass-to-charge ratio and complicating compound identification.
Innovation Solution
A method and apparatus that react precursor ions with a known radical to generate fragment and adduct ions, setting the detector gain to avoid saturation in fragment and adduct ions while allowing saturation in precursor ions, enabling accurate mass determination by subtracting the radical's mass from the adduct ion's mass.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the detector gain is set high to detect fragment ions, then the fragment ion signal intensity is sufficient, but the precursor ion peak becomes deformed making peak top determination impossible
Solution Approach 1:
The adduct ion acts as an intermediary reference that preserves peak shape information. By measuring the adduct ion peak top position instead of the saturated precursor ion peak, the system accurately determines mass-to-charge ratio without the peak deformation that occurs at high detector gain settings.
2Measurement precision
If the detector gain is reduced to avoid precursor ion saturation, then the mass-to-charge ratio accuracy is maintained, but the fragment ion intensity becomes insufficient for reliable detection
Solution Approach 1:
The adduct ion serves as a mediator that provides an alternative detection pathway. Instead of relying on fragment ion intensity, the system uses the adduct ion signal to determine mass-to-charge ratio, thereby maintaining measurement precision without requiring high fragment ion signal intensity.
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 allows for precise determination of the precursor ion's mass-to-charge ratio by measuring adduct ions with sufficient intensity, correcting errors in precursor ion estimation and enhancing compound identification accuracy.
Implementation Method 1
measuring ions including the precursor ion, the fragment ions, and the adduct ion by the detector to obtain a mass spectrum
Implementation Method 2
reacting a precursor ion with a radical of a known type to generate fragment ions and an adduct ion
Data Source
AI summary
Provided is a mass spectrometer including: a reaction chamber into which a precursor ion is introduced; a radical generation part configured to generate a known radical; a radical supply part configured to react the precursor ion with the radical to generate fragment ions and an adduction; a measurement control part configured to measure ions including the precursor ion, the fragment ions, and the adduct ion to obtain a mass spectrum; and an accurate mass estimation part configured to specify a peak of the adduct ion by searching a predetermined mass range centered on a mass value obtained by adding a mass of an atom or molecule derived from the radical to a mass obtained from a peak of the precursor ion, and estimate an accurate mass of the precursor ion by subtracting an accurate mass of the atom or molecule from an accurate mass of the peak.