The operation process of Shimadzu gas chromatography-mass spectrometry (GC-MS) includes six core steps: start-up preparation, system configuration, tuning leak detection, sample injection, data acquisition, and shutdown maintenance. The specific operations are as follows:
1、 Power on preparation
Air source inspection
Open the helium cylinder and adjust the pressure gauge to 0.6-0.8MPa to ensure that the purity of helium gas is ≥ 99.999%.
Check if the air circuit connection is tight to avoid leakage.
Instrument powered on
Power on the devices in order: GC host, MS host, computer monitor, and printer.
After starting the computer, double-click the desktop icon (such as "GCMSRealTimeAnalysis") to enter the real-time analysis software.
2、 System configuration and initialization
Unit selection
Click on 'SystemConfiguration' in the software interface, select the required components (such as GC, MS) from the 'Valid Units' list, and register them in the' Usage Units'.
Parameter Settings
Injection port: Set the temperature (usually 250-290 ℃), split ratio, and carrier gas flow rate.
Chromatography column: Select the column type and set the column temperature program (such as initial temperature of 60 ℃, heating rate of 30 ℃/min to 240 ℃).
Ion source: Set temperature (such as 200 ℃), interface temperature (such as 280 ℃), and detector voltage.
Scanning mode: Choose between full scan (SCAN) or ion monitoring (SIM) according to your needs.
Vacuum start
Click on 'VacuumControl' and 'AutoStartup', and the system will automatically start the vacuum pump, preheat the turbo pump, and heat up the ion source.
Observation of vacuum degree: High vacuum should reach 10 ⁻³ -10 ⁻⁴ Pa, and low vacuum should be around 100-101Pa.
3、 Tuning and leak detection
Automatic tuning
Click on 【 Tuning 】 【 AutoTuning 】, and the system will automatically optimize the mass spectrometry parameters.
After tuning is completed, check the report:
The base peak should be m/z18 or 69, and the intensity of m/z28 should be ≤ 1/2 of m/z69.
Detector voltage ≤ 1.5kV, FWHM deviation ≤ 0.1.
Leakage inspection
Monitor the ion strength of m/z18 (H ₂ O) and m/z28 (N ₂) in PeakMonitorView.
If the strength of m/z28 is greater than twice that of m/z18, there may be a leak, and it is necessary to use petroleum ether for leak detection.
4、 Sample injection and data collection
Sample preparation
Liquid sample: Dilute to the appropriate concentration, manually inject with a microsyringe or place in an automatic sampler.
Solid sample: Grind and extract, then transfer to solution.
Avoid sample contamination and ensure accurate injection volume (micro upgrade to micro upgrade).
Sample injection operation
Manual injection: Use a microsyringe to inject the sample into the injection port and quickly press the 【 Start 】 button.
Automatic injection: Set the sample bottle number, injection volume, and batch processing table in the software, and click 【 Start 】 to run automatically.
data collection
The instrument separates sample components according to set parameters, and the mass spectrometer detects and generates chromatograms and mass spectra.
Real time monitoring of instrument status to ensure no abnormalities.
5、 Data Processing and Analysis
qualitative analysis
Double click the peak vertex on the chromatogram to view the mass spectrum.
Match standard spectra through spectral library search (similarity search) to determine component structure.
Produce a qualitative report that includes sample information, chromatograms, and search results.
quantitative analysis
Create a component table, set the number of calibration curve points, fitting type, and units.
Input the concentration of the standard solution and generate a quantitative report.
6、 Shutdown and maintenance
Cooling and shutdown
Click on 【 VacuumControl 】 【 AutoShutdown 】, and the instrument will automatically cool down to 120 ℃ before shutting down the vacuum system.
Turn off the power supply of the gas chromatography and mass spectrometry host, and finally turn off the computer.
routine maintenance
Chromatography column: regularly aged (10-20 ℃ higher than the highest temperature of the program, lasting for 30 minutes to 1 hour).
Ion source: Clean the filament and lens to extend their service life.
Vacuum system: Check the status of the turbo molecular pump to avoid frequent starting and stopping.