Detailed explanation of components and spare parts of liquid chromatography-mass spectrometry (LC-MS) and gas chromatography-mass spectrometry (GC-MS)
Liquid chromatography-mass spectrometry (LC-MS) and gas chromatography-mass spectrometry (GC-MS) are one of the most important instruments in modern analytical chemistry, which are widely used in pharmaceutical analysis, environmental monitoring, food safety, metabonomics and other fields. They combine the separation ability of chromatography with the qualitative ability of mass spectrometry, and can realize the accurate analysis of complex samples.
Due to the complex structure of LC-MS and GC-MS, involving many key components and spare parts, their maintenance and spare parts management are very important for instrument performance. This paper will introduce the core components, common spare parts and replacement suggestions of these two types of instruments in detail.
1. Components and spare parts of liquid chromatography-mass spectrometry (LC-MS)
(1) Main components
① liquid chromatography section (LC)
Infusion Pump
Provide a stable high pressure (usually 300-400 bar) to drive the mobile phase through the chromatographic column.
Key spare parts: pump gasket, check valve and plunger rod.
Injector/Autosampler
Automatic sample injection ensures accurate sample injection.
Key spare parts: injection needle, injection valve and sealing ring.
Column
C18, C8, HILIC and other stationary phases are commonly used to separate samples.
Key spare parts: chromatographic column gasket and Guard Column.
Oven (oven)
Control the temperature of chromatographic column to improve the separation efficiency.
Key spare parts: temperature sensor and fan.
② Mass spectrometry (MS)
Ion Source
ESI (Electrospray Ion Source): Suitable for polar compounds.
APCI (atmospheric pressure chemical ionization source): suitable for moderately polar compounds.
NanoESI (nano-liter electrospray): suitable for micro-samples.
Key spare parts: ion source nozzle, atomizer, heating module, ion lens.
Mass Analyzer (mass analyzer)
Quadrupole: used for screening target compounds (such as triple quadrupole MRM).
TOF (Time-of-Flight Mass Spectrometry): High resolution, suitable for metabonomics.
Orbitrap/FT-ICR: Ultra-high resolution, suitable for protein omics.
Key spare parts: ion lens and internal components of mass analyzer (rarely replaced).
Detector (detector)
Electron multiplier (EM): Detect ion signal.
Key spare parts: electronic multiplier (life is about 1-2 years, depending on the use).
Vacuum System (vacuum system)
Roughing Pump)+ Turbo Pump: maintain the high vacuum environment of mass spectrometer.
Key spare parts: turbomolecular pump bearing, Ion Gauge and sealing ring.
Data processing system (Data System)
Mass chromatography software: controls instruments and analyzes data.
(2) Common spare parts and replacement suggestions
Maintenance suggestion of component function replacement cycle
The sealing gasket of infusion pump prevents the mobile phase from leaking for 1-2 years or periodically checks the pressure stability when leakage occurs.
Injection needle/valve Sample injection The automatic injector needs to be calibrated regularly every 1000-2000 injections.
The ionized samples of ESI/APCI nozzle are often blocked after 6-12 months (depending on the frequency of use), and need to be cleaned regularly.
Clean or replace the ion lens after focusing the ion beam for 1-2 years or when its performance declines.
The bearing of turbomolecular pump shall be kept in vacuum for 3-5 years to monitor the vacuum degree, and it shall be overhauled if it is abnormal.
The service life of ion signal detected by electron multiplier is limited in 1-2 years, so it is necessary to detect the sensitivity regularly.
Atomizer/heating module ESI/APCI ionization shall be cleaned or replaced for 1-2 years to prevent blockage.
2. Components and spare parts of gas chromatography-mass spectrometry (GC-MS)
(1) Main components
① gas chromatography (GC)
Gas path system
Carrier gas (helium/hydrogen/nitrogen)+gas purifier (to remove moisture and oxygen).
Key spare parts: gas filter and pressure stabilizing valve.
sampling system
Split-flow/non-split-flow inlet: suitable for different sample types.
Autosampler: Improve the analysis efficiency.
Key spare parts: injection spacer, liner and O-ring.
chromatographic column
Capillary Column: most commonly used, such as DB-5, DB-WAX, etc.
Key spare parts: column gasket and Guard Column.
Column temperature box
Control the temperature and support the programmed heating.
Key spare parts: temperature sensor and fan.
② Mass spectrometry (MS)
Ion Source
EI (electron bombardment ion source): most commonly used, suitable for qualitative analysis.
CI (chemical ionization source): suitable for specific compounds.
Key spare parts: ion source filament and ion source components (such as ion box and repulsion electrode).
Mass Analyzer (mass analyzer)
Quadrupole: used for screening target compounds (such as SIM/SCAN mode).
TOF (Time of Flight Mass Spectrometry): High resolution, suitable for complex samples.
Key spare parts: ion lens and internal components of mass analyzer (rarely replaced).
Detector (detector)
Electron multiplier (EM): Detect ion signal.
Key spare parts: electronic multiplier (life is about 2-3 years).
Vacuum System (vacuum system)
Mechanical pump+turbomolecular pump: maintain high vacuum environment.
Key spare parts: turbomolecular pump bearing, vacuum gauge and sealing ring.
Data processing system (Data System)
Mass chromatography software: controls instruments and analyzes data.
(2) Common spare parts and replacement suggestions
Maintenance suggestion of component function replacement cycle
Injection spacer prevents carrier gas from leaking. Check the injection port pressure regularly every 100-200 injections.
Gasification of liner /O-ring samples should be cleaned or replaced every 200-500 injections to prevent pollution.
EI filament ionization samples have a limited life span of 6-12 months (depending on the frequency of use) and need to be replaced regularly.
Ionization and focusing of ion source components shall be cleaned or replaced for 1-2 years to prevent pollution.
The bearing of turbomolecular pump shall be kept in vacuum for 3-5 years to monitor the vacuum degree, and it shall be overhauled if it is abnormal.
The service life of electron multiplier in detecting ion signals is limited in 2-3 years, so it is necessary to detect the sensitivity regularly.
3. Maintenance comparison between LC-MS and GC-MS.
Comparison item LC-MS GC-MS
Main ion sources ESI/apci/nano ESI ei/ci
Carrier gas liquid mobile phase (water/organic solvent) helium/hydrogen/nitrogen
Key consumables ion source nozzle, atomizer injection spacer, EI filament
Vacuum system turbomolecular pump+mechanical pump turbomolecular pump+mechanical pump
Mass spectrometer detector electron multiplier electron multiplier
Typical fault nozzle blockage, ion source pollution, filament aging and sample inlet pollution.
