GC-MS Interface
Definition
The physical link between a gas chromatograph and a mass spectrometer. Older designs used jet separators and open splits to manage the carrier-gas load on the vacuum system. Modern capillary-column GC-MS sends the entire column effluent directly into the ion source, with the small carrier-gas flow handled by a turbomolecular pump.
- Function
- Physical link between a gas chromatograph and mass spectrometer
- Older design
- Jet separators and open splits
- Modern design
- Direct capillary-column effluent into the ion source
- Vacuum handling
- Turbomolecular pump manages carrier-gas flow
Common questions
Why did older packed-column GC-MS systems need a jet separator?+
Packed columns carried a much higher carrier-gas flow than the mass spectrometer's vacuum system could tolerate, so a jet separator selectively removed excess carrier gas while passing the analyte molecules through, protecting the vacuum from being overwhelmed.
What changed to allow direct interfacing in modern instruments?+
Capillary columns run at far lower carrier-gas flow rates than packed columns, low enough that a turbomolecular pump can maintain vacuum even with the full column effluent entering the source directly, removing the need for a separate gas-reduction device.
Does the interface design affect sensitivity for forensic analysis?+
Yes, direct capillary interfacing delivers a greater proportion of the separated analyte into the ion source without the losses inherent in older separator designs, contributing to the improved sensitivity of modern GC-MS over legacy instrumentation.
Related terms
- Atmospheric Pressure Chemical Ionisation (APCI)
- A complementary atmospheric-pressure source that vaporises the LC eluent and uses a corona discharge to ionise a reagent gas, which transfers charge...
- Electrospray Ionisation (ESI)
- A soft atmospheric-pressure ionisation source that sprays the LC eluent through a charged capillary into a heated counter-current gas, producing protonated or...
- Hyphenated Technique
- A single workflow that couples a separation method to a spectroscopic detector, so a complex mixture is resolved and each component identified...
- MRM (Multiple Reaction Monitoring)
- A targeted MS/MS scan mode on a triple quadrupole that monitors specific precursor-to-product ion transitions, with two transitions per analyte (quantifier and...
- Vapour-Phase IR Spectrum
- The infrared spectrum recorded as a GC analyte elutes into a heated light pipe inside the FTIR cell, with no solvent or...