Tandem Mass Spectrometer High-Accuracy Mass Correction
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Solution Overview
Problem
Tandem mass spectrometers, such as Q-TOF mass spectrometers, face challenges in high-accuracy mass correction and sensitivity when combined with liquid or gas chromatographs, due to limitations in ion accumulation and measurement throughput, whereas IT-TOFMS offers high-precision but is expensive and less sensitive.
Innovation Solution
A tandem mass spectrometer design that includes a first mass separator, a collision cell for dissociation, and a second mass separator for product ion analysis, with an analysis controller and correction processor to perform mass scans and correct product ion mass-to-charge ratios using a standard sample's known mass-to-charge ratio, allowing for high-accuracy mass determination without the need for continuous ion cooling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a tandem mass spectrometer uses a collision cell for CID dissociation, then MS/MS analysis capability is achieved, but mass calibration accuracy deteriorates compared to IT-TOFMS
Solution Approach 1:
The system performs preliminary mass calibration using a standard sample before analyzing the target sample. The calibration data obtained from the standard sample is stored and then used to correct the mass-to-charge ratios during subsequent target sample analysis, ensuring high mass calibration accuracy in MS/MS mode without requiring ion trap technology.
2Measurement precision
If a tandem mass spectrometer performs continuous scan measurements for mass calibration, then measurement throughput decreases, but mass calibration accuracy improves
Solution Approach 1:
The system performs mass calibration measurements using a standard sample in advance before analyzing the target sample. The obtained calibration data is stored and reused for correcting mass-to-charge ratios during target sample analysis, eliminating the need for continuous calibration scans and thereby maintaining high measurement throughput while ensuring accurate mass calibration.
Solution Approach 2:
The system creates a calibration model from the standard sample measurement and applies this copied calibration information to correct the target sample analysis. This allows the calibration data to be reused across multiple target sample measurements without repeating the calibration process each time.
3Ease of manufacture
If a tandem mass spectrometer uses quadrupole mass filters, then device cost is reduced, but mass resolving power and accuracy deteriorate compared to time-of-flight analyzers
Solution Approach 1:
The system uses a correction processor that applies feedback based on calibration data from standard samples to correct the mass-to-charge ratios measured by the quadrupole mass filters. This feedback mechanism compensates for the lower inherent accuracy of quadrupole filters, achieving mass measurement accuracy comparable to more expensive time-of-flight based systems.
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
Enables high-accuracy mass correction of product ions in tandem mass spectrometers, reducing measurement time and improving sensitivity, comparable to internal standard methods, while maintaining high reproducibility and peak waveform accuracy.
Implementation Method 1
a collision cell for dissociating the precursor ion
Implementation Method 2
a time-of-flight mass analyzer in place of the rear quadrupole mass filter
Data Source
AI summary
Under the control of an analysis control unit (5), a mass spectrometer unit (2) performs a product-ion scan measurement for a target component in a target sample within a time range where the component is introduced. It also performs a scan measurement over an m/z range including the m/z of an ion originating from a standard component within the same segment of time. A mass correction information calculator (42) calculates mass correction information from measured and theoretical values of the m/z of the ion originating from the standard component observed on an MS spectrum obtained by the scan measurement. Using the mass correction information, a mass corrector (43) corrects the m/z of each ion peak originating from the target component observed on an MS/MS spectrum obtained by the product-ion scan measurement performed within the same cycle as the scan measurement concerned. It is possible to consider that the MS measurement and the MS/MS measurement within the same cycle have been almost simultaneously carried out. Accordingly, a mass correction which is almost equivalent to an internal standard method can be achieved.