Interface
Definition
The hardware bridge that transfers analyte from the separation stage to the detector while removing the unwanted mobile phase (carrier gas, solvent, plasma).
- Field
- Hyphenated instrumental analysis
- Function
- Transfers analyte to detector, removes mobile phase
- Removes
- Carrier gas, solvent, or plasma depending on technique
- Examples
- GC-MS transfer line, LC-MS electrospray source
Common questions
Why can't the mobile phase simply be carried through into the detector?+
Most detectors, particularly mass spectrometers, require high vacuum or a clean ionisation environment, so bulk carrier gas or solvent would overwhelm the detector or suppress ion signal, making removal at the interface essential before the analyte reaches the detection stage.
How does the interface differ between GC-MS and LC-MS instruments?+
A GC-MS interface is typically a heated transfer line into the vacuum system since the carrier gas is already low in volume, while an LC-MS interface must handle a liquid solvent, commonly through electrospray ionisation, which nebulises and ionises the eluent as the solvent evaporates.
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...
- Hyphenation
- Online coupling of a separation technique (GC, LC, ICP) with a spectrometric detector (MS, FTIR) so identification happens within the same run....
- ICP Plasma
- Inductively coupled argon plasma at 6,000 to 10,000 K that atomises and ionises samples in ICP-MS, generating singly charged elemental ions for...
- Internal Standard / Deuterated Standard
- A chemically similar (often perdeuterated) compound spiked into the sample to correct for matrix effects and ionisation suppression. Standard practice in forensic...
- Isotope Ratio Mass Spectrometry (IRMS)
- Specialised MS that measures precise ratios of light stable isotopes (delta values of 2H, 13C, 15N, 18O, 34S) on a continuous-flow combustion...
- Jet Separator
- Early GC-MS interface (Ryhage, 1964) that used differential pumping through a nozzle to enrich analyte and bleed helium. Replaced by direct capillary...