Research And Software Development Of Automatic Adjustment Of Electrical Parameters On Single Quadrupole Mass Spectrometer

Mass spectrometry is a precise analytical method for the qualitative or quantitative analysis of a substance to be tested.There are many types of mass spectrometers,of which single quadrupole mass spectrometers have been widely used in food safety testing,environmental safety monitoring,drug development and quality monitoring.Mass spectrometers are sophisticated and complicated,requiring more electrical parameters to be adjusted,and irrational parameter settings will cause large deviations in experimental results.The manual adjustment of the electrical parameters of the mass spectrometer is not only cumbersome and time-consuming,but also introduces human errors,resulting in inaccurate experimental results.Users of mass spectrometers are often not instrument development engineers and do not have the ability to adjust the electrical parameters of the instruments.So there is an urgent need for automatic parameter adjustment.This paper mainly studies the automatic adjustment function of the RF power frequency and the mass resolution of the single quadrupole mass spectrometer.The instrument control software is designed to monitor the electrical parameters of the instrument and implement the automatic adjustment algorithm.Changes in instrument hardware often result in changes in the RF power resonance frequency,and the resonance frequency varies from instrument to instrument.The RF power determines the detection range of the mass spectrometer.In order to ensure the maximum detection range of the instrument,the RF power needs to be adjusted to the resonance state.According to the characteristic that the output voltage reaches the maximum value when the RF power is resonant,an automatic tuning algorithm based on the relationship between the frequency and the feedback voltage is studied through the voltage value of the RF power output feedback channel.In addition,the problem that the maximum output voltage cannot be obtained due to the saturation of the feedback voltage found in the experiment is studied.According to the characteristics of the feedback voltage value and its change rate,a mechanism for judging whether the feedback voltage is saturated is established.At the same time,the change rate of the feedback voltage value is used to fit the feedback voltage value curve to obtain the resonance frequency.Changes in ambient temperature and humidity,as well as external forces such as collisions and vibrations,may cause changes in the mass resolution of the instrument.In order to ensure that the mass resolution meets the needs of the experiment,the instrument needs to be adjusted for mass resolution before the experiment.In this paper,through research on the theory of quadrupole and mass resolution,it is concluded that there is a linear relationship between mass resolution and the electrical parameters of the instrument Reso and DM.Using this linear relationship,an automatic adjustment algorithm for mass resolution is established.The mass resolution of the mass spectrometer is reflected by the full width at half maximum(FWHM)parameter.The algorithm realizes the detection of FWHM.The instrument is adjusted by using the linear relationship between FWHM and Reso and DM,to finally achieve the goal of FWHM,to achieve the purpose of automatically adjusting the mass resolution.The single quadrupole mass spectrometer must be operated by special control software.This study developed a control software based on the work flow and automatic adjustment algorithm flow that must be followed for the use of a single quadrupole mass spectrometer.This software has remote connection of the instrument,parameter monitoring and setting,mass axis calibration,scanning parameter configuration,mass spectrometry data display and other functions.The software was used to test the above-mentioned automatic tuning algorithm for RF power supply and the automatic adjustment algorithm for mass resolution,and the experimental results obtained were as expected.Compared with manual adjustment,the automatic adjustment method establishes a unified adjustment standard and greatly shortens the adjustment time.The RF power source automatic tuning algorithm and the mass resolution automatic adjustment algorithm are universal to the single quadrupole mass spectrometer,which reduces the requirements for the operator's ability to adjust the instrument and improves the performance of the instrument.