Mass Spectrometer Calibration via Quadrupole Voltage Fitting
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Solution Overview
Problem
Current mass spectrometer calibration methods are inflexible, time-consuming, and prone to failure due to technical instabilities, requiring repeated scans and being dependent on initial conditions, with limited ability to handle outliers and flexible fitting algorithms.
Innovation Solution
A method for calibrating mass spectrometers that involves calibrating the second mass analyzer first, then the first quadrupole in a mass selecting mode, using a step-wise approach to determine and fit RF and DC voltage values for specific masses, with iterative evaluation and adjustment to meet quality conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional calibration methods are used with fixed initial conditions and single-mass scanning, then calibration can be performed, but the process becomes time-consuming and requires repeated scans
Solution Approach 1:
The calibration process is segmented into multiple independent calibration runs, each focusing on different mass ranges or specific calibration masses. This allows parallel processing and eliminates the need for repeated full-range scans, significantly reducing total calibration time while maintaining accuracy through targeted calibration of specific mass segments
Solution Approach 2:
The method performs preliminary determination of RF and DC voltage values for multiple calibration masses before conducting the actual fitting process. This preliminary action includes estimating initial voltage values and preparing calibration data structures in advance, which streamlines the subsequent calibration execution and reduces iterative scanning requirements
2Ease of operation
If strict fitting functions are assumed during calibration, then the fitting process becomes simpler, but the method loses flexibility and cannot accommodate deviations from assumed functions
Solution Approach 1:
The calibration method dynamically selects and adjusts fitting functions based on the actual calibration data characteristics rather than assuming a fixed function form. The system can adapt between linear and non-linear fitting approaches, and automatically adjusts the complexity of fitting functions to match the data quality and instrument performance, providing both simplicity when appropriate and flexibility when needed
Solution Approach 2:
The method changes the parameters and form of fitting functions during the calibration process based on data analysis. It can transition between different functional forms (e.g., linear vs. quadratic), adjust polynomial degrees, and modify fitting weights dynamically, allowing the calibration to accommodate various instrument behaviors without requiring predetermined rigid function assumptions
3Productivity
If calibration is performed with technical instabilities present, then calibration can proceed, but outliers lead to failure and poor calibration results
Solution Approach 1:
The calibration method incorporates feedback mechanisms that continuously monitor calibration data quality and detect outliers during the calibration process. When instabilities or outliers are detected, the system can automatically adjust calibration parameters, repeat specific measurements, or flag problematic data points for review, thereby maintaining high success rates even when technical instabilities are present during calibration
4Quantity of substance
If multiple calibration masses with overlapping signals are used, then more calibration data can be obtained, but traditional methods cannot properly handle the overlapping signals
Solution Approach 1:
The method introduces intermediate processing steps that decompose and separate overlapping calibration signals before fitting. It uses intermediate representations of mass spectra that allow mathematical separation of overlapping peaks through deconvolution techniques, enabling the simultaneous use of multiple calibration masses with overlapping signals without requiring complex manual signal processing or sequential calibration approaches
Data Source
AI summary
A method of calibrating a mass spectrometer is disclosed. The mass spectrometer includes a first quadrupole, a second mass analyzer and a detection means. The method includes calibrating the second mass analyzer at a first time, calibrating the first quadrupole at a second time later than the first including a) determining for each of several selected masses a corresponding value of the amplitude of the RF voltage and DC voltage applied to the electrodes of the first quadrupole, b) fitting a function of the selected mass to the values of the amplitude of the RF voltage and DC voltage corresponding to the several selected masses, c) detecting the selected mass in a filter window width over a mass range, d) evaluating a shift of the peak position and/or a deviation of the filter window width, and e) repeating the calibration steps under certain conditions.