MS/MS Mass Spectrometer Calibration for CID Gas Time Delays
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Solution Overview
Problem
The high gas pressure in the collision cell of MS/MS mass spectrometers due to continuous CID gas supply causes ions to lose kinetic energy, leading to time delays and mass shifts, which deteriorate analysis sensitivity and accuracy in neutral loss scan and auto MS/MS measurements.
Innovation Solution
An MS/MS mass spectrometer with a calibrating analysis execution means to collect mass analysis data under CID gas conditions, creating mass calibration information to correct for time delays, and an input means to adjust mass-scan operations based on this information to maintain accurate mass-to-charge ratios during neutral loss and precursor ion scans.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If CID gas is continuously supplied into the collision cell to maintain high gas pressure for effective ion dissociation, then the dissociation efficiency is improved, but ions lose kinetic energy causing time delays and mass shifts that deteriorate analysis sensitivity and accuracy
Solution Approach 1:
The system performs a mass scan operation before the actual MS/MS analysis to measure the time delay caused by CID gas in the collision cell. This preliminary measurement allows the system to calculate and store correction values that are applied during subsequent analyses, compensating for the kinetic energy loss and mass shifts without reducing the CID gas pressure.
2Productivity
If the mass scan operation is performed without correcting for time delay, then the analysis speed is maintained, but the mass axis accuracy deteriorates due to mass shifts
Solution Approach 1:
The system uses the mass scan results to generate feedback in the form of correction values that represent the time delay and mass shift caused by CID gas. These correction values are stored and automatically applied to subsequent MS/MS analysis operations, creating a closed-loop system that continuously compensates for the adverse effects of CID gas without sacrificing analysis speed.
3Measurement precision
If correction values are calculated and applied based on mass scan operations, then mass axis accuracy is improved, but the device complexity increases
Solution Approach 1:
The system performs self-calibration by automatically executing mass scan operations to measure its own time delay and mass shift characteristics. The correction values are calculated and stored within the system itself, allowing the mass spectrometer to self-correct without requiring external calibration equipment or complex additional hardware components.
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 solution improves detection sensitivity and mass axis accuracy by correcting for time delays and kinetic energy variations, ensuring precise mass analysis and reduced mass shift across the entire mass-scan range.
Implementation Method 1
A voltage composed of a DC voltage and a radio-frequency (RF) voltage is applied to the first-stage quadrupole (Q1) 13. Due to the effect of the quadrupole electric field generated by this composite voltage, only a target ion having a specific mass-to-charge ratio is selected as a precursor ion
Implementation Method 2
After being sent from the first-stage quadrupole 13 to the second-stage quadrupole 15, the precursor ion collides with the CID gas in the collision cell 14, to be dissociated into product ions by a CID process
Implementation Method 3
A voltage composed of a DC voltage and a radio-frequency voltage is applied to the third-stage quadrupole (Q3) 17. Due to the effect of the quadrupole electric field generated by this voltage, only a product ion having a specific mass-to-charge ratio is selected in the third-stage quadrupole 17
Implementation Method 4
a detector 18 for detecting ions and producing detection signals corresponding to the amount of detected ions
Data Source
AI summary
A mass analysis of a sample having a known mass-to-charge ratio is carried out by performing a scan at a first-stage quadrupole over a predetermined mass range, under the condition that a collision induced dissociation gas is introduced into a collision cell and a voltage applied to a third-stage quadrupole is set so that no substantial mass separation occurs in this quadrupole. Various product ions originating from a precursor ion selected by the first-stage quadrupole arrive at and are detected by a detector without being mass separated. Accordingly, based on the detection data, a data processor can obtain a relationship between the voltage applied to the first-stage quadrupole and the mass-to-charge ratio of the selected ions, with a time delay in the collision cell reflected in that relationship. This relationship is stored in a calibration data memory, to be utilized in a neutral loss scan measurement or the like.