Agilent GCMS gas chromatography-mass spectrometryPractical Guide to Process Operation and Data Analysis

Detailed explanation of the usage process

Power on preparation and system startup

Gas inspection: Ensure that the purity of helium/nitrogen is ≥ 99.999%, the pressure is stable (0.4-0.6MPa), and avoid hydrocarbon contamination.

Instrument startup: Start the computer, gas chromatography (such as 7890A), mass spectrometry detector (such as 5975C) in sequence, turn on the molecular turbo pump to evacuate (about 2-4 hours), and enter the workstation after the vacuum degree reaches the standard (turbo pump speed ≥ 95%).

Environmental requirements: Temperature between 15-35 ℃, humidity between 40% and 80%, avoiding electromagnetic interference.

System tuning and calibration

Air and water inspection: Scan m/z 18 (water), 28 (nitrogen), and 32 (oxygen) through the tuning interface to ensure that the abundance is ≤ 5% (nitrogen/oxygen) or ≤ 10% (water), and confirm that there is no air leakage.

Auto tuning: Execute the ATUNE. U tuning program to optimize the EM voltage (1200-2500V), peak shape (base peak ≥ 300000), and full width at half maximum (0.55 ± 0.10U) to ensure fragment ion symmetry.

Gain tuning: GainAutotune is used to enhance sensitivity and is suitable for complex matrix analysis.

Sample processing and injection

Sample preparation: Select a suitable solvent (such as methanol, acetone) and dissolve the sample to a concentration of 1-100 μ g/mL to avoid particle blockage of the injection port.

Injection parameters: Set the injection port temperature (220-290 ℃), split ratio (50:1), column temperature program (such as initial temperature of 60 ℃, heating rate of 10 ℃/min to 280 ℃), and carrier gas flow rate of 1-2mL/min.

Automatic injection: Use an automatic sampler to ensure that the injection accuracy is ≤ 1%.

Data Collection and Analysis

Scanning mode: FullScan is used for qualitative analysis, while ion monitoring (SIM) is selected for quantitative analysis, with a mass to charge ratio range of m/z 50-1000.

Data processing: Peak detection, deconvolution, and spectral library matching (NIST library) are performed using MassHunter software, combined with internal standard methods (such as n-alkanes) for quantification, and background subtraction is used to improve signal-to-noise ratio.

Result verification: The linear correlation coefficient of the calibration curve is ≥ 0.99, and the recovery rate is 80% -120%, RSD≤10%。

Agilent GCMSShutdown and maintenance of gas chromatography-mass spectrometry

Emptying procedure: Reduce the temperature of the ion source (100 ℃) and quadrupole (150 ℃), turn off the vacuum pump, and turn off the power after the turbo pump speed is ≤ 10%.

Daily maintenance: Regularly clean the injection port, replace the spacer/O-ring, bake the ion source (300 ℃ × 2h) to remove residues, and check the aging condition of the chromatographic column.

Safety regulations: Wear protective equipment, avoid direct contact with high-temperature components, and handle exhaust gas/waste liquid professionally.

Technical highlights and advantages

High sensitivity: using HES2.0 ion source, with a detection limit of Ak level, suitable for ultra trace analysis (such as environmental pollutants, pesticide residues).

High stability: Gold plated quadrupole and JetClean intelligent hydrogen cleaning technology extend maintenance cycles and reduce downtime.

Intelligent software: MassHunter 13.0 supports SWARM automatic tuning, retention time locking, simplifies method development, and improves data consistency.

Widely applicable: covering environmental monitoring (VOCs, organochlorine pesticides), food safety (flavor substances, additives), biomedicine (metabolomics) and other fields.