Quadrupole Mass Filter Charge-Up Prevention
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
In mass spectrometers, charge-up on ion transport optical systems leads to a decrease in ion intensity over time, affecting measurement sensitivity and accuracy.
Innovation Solution
Implementing a controller to temporarily reverse the polarity of the direct-current voltage applied to ion transport optical systems during pause times in SIM or MRM measurements, thereby dispersing accumulated charges and reducing charge-up, while optimizing the duration of polarity reversal based on pause time lengths to maintain ion intensity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If ions are repeatedly introduced into the mass spectrometer for continuous measurement, then measurement productivity is improved, but charge-up accumulates on ion transport optical systems causing ion intensity to decrease over time
Solution Approach 1:
The patent applies periodic reversal of the direct-current voltage polarity during pause times in SIM or MRM measurements. By temporarily changing the voltage polarity at regular intervals (during pause periods between ion detection cycles), accumulated charges on insulating surfaces are dispersed, preventing charge-up while maintaining continuous measurement capability.
2Reliability
If the direct-current voltage polarity is reversed during pause time, then charge-up is reduced, but measurement time is increased due to additional voltage switching
Solution Approach 1:
The patent performs charge dispersal action during the pause time that already exists in SIM or MRM measurement cycles. By utilizing the idle pause period between ion detection cycles to reverse the voltage polarity, the system prevents charge-up without extending the overall measurement time, as the voltage reversal occurs during already-allocated pause intervals.
3Stability of the object's composition
If insulating materials are used to hold ion transport optical systems, then structural stability is improved, but charge-up occurs more easily on these insulating surfaces
Solution Approach 1:
The patent converts the harmful charge-up effect into a manageable periodic phenomenon. Instead of trying to prevent charge accumulation entirely, the system allows charges to accumulate during ion detection cycles, then uses voltage polarity reversal during pause times to disperse these charges. This transforms the continuous harmful effect into a periodic, controlled process that maintains structural stability while preventing detrimental charge-up.
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 effectively prevents or reduces charge-up, maintaining high sensitivity and accuracy of ion detection by ensuring ions can pass through the system without interference, thereby stabilizing ion intensity over time.
Implementation Method 1
one or more ion transport optical systems for transporting ions by the effect of an electric field between an ion source and an ion detector
Implementation Method 2
if the polarity of the ion to be monitored in an SIM or MRM measurement is unchanged before and after the switching of the mass-to-charge ratio, then the direct-current voltage applied to the at least one ion transport optical system is temporarily changed to either a level at which the direct-current voltage has a polarity different from the polarity of the direct-current voltage at those specific levels
Data Source
Figure 1~2
Figure 3~4B
Figure 5
AI summary
In a pause time assigned for switching the voltage applied to a quadrupole mass filter or other ion transport optical system so as to switch the mass-to-charge ratio of a target ion in an SIM measurement, the polarity of the direct-current voltage applied to a pre-quadrupole mass filter is temporarily reversed. The voltage polarity reversal time is changed according to the length of the pause time so that the ion intensity can sufficiently rise by the time the next dwell time begins. When the polarity of the voltage applied to the pre-quadrupole mass filter is reversed, the electric charges which lie on an insulating film of contaminants or other substances attached to the surface of the pre-quadrupole mass filter or on an insulating support structure are dispersed, whereby the charge-up is eliminated. Furthermore, since the ions are prevented from passing through, the charge-up of a main quadrupole mass filter in the subsequent stage is also reduced.