GC systems

A GC system is a gas chromatograph, an instrument that separates and measures volatile and semi-volatile compounds by carrying a sample in a gas stream through a column that holds each component back for a different length of time. It includes the injector, the oven-held column, the detector, and often an autosampler and data system.

GC stands for gas chromatography. The term describes both the separation technique and the instrument that performs it.

A sample is injected and vapourised at the inlet, then swept by a carrier gas through a heated column where each compound is retained for a characteristic time before reaching the detector. The detector converts the eluting compounds into a signal, producing peaks whose position identifies and whose area quantifies each component.

The listings cover the core gas chromatograph with its oven, column and detector, full chromatography systems that bundle a data station and sample handling, standalone and built-in autosamplers, and GC-MS where the chromatograph is joined to a mass spectrometer. Broader labels such as analytical instrument and laboratory analyser catch configurations that sit across these lines or are listed by function.

They separate and measure volatile and semi-volatile compounds in applications such as metabolomics, lipidomics, residual solvent testing in biomanufacturing, and fermentation monitoring through headspace analysis. A GC-MS adds compound identification, while single-detector instruments handle routine quantification of hydrocarbons, solvents and fatty acid methyl esters.

Start with the detector, because it decides most of what the instrument can do: a flame ionisation detector suits routine organics, a thermal conductivity detector reads fixed gases, an electron capture detector finds halogenated traces, and a mass spectrometer confirms identity. Then match the inlet, column and oven temperature range to the compounds and boiling-point window you run, since none of this is visible from a photograph and must be read off the specification.

A used unit is sold in its existing condition, while a refurbished unit has been cleaned, tested and brought back to working order before listing. Both are listed below the price of new, and the exact scope of any refurbishment should be confirmed in the individual listing.

Prices in the Questpair catalogue range from EUR 40 to EUR 64.567, with an average around EUR 6.937. The spread reflects the gap between a single-detector benchtop chromatograph and a complete GC-MS with autosampler and data system.

The names appearing most in these listings are Agilent, Agilent Technologies, Varian, Thermo Scientific and HP. Agilent and its earlier HP-badged instruments make up a large part of the catalogue, while Varian and Thermo Scientific broaden the range of inlet and detector configurations.

A warranty is often possible and is arranged in consultation for the specific listing. Check the listing and confirm the terms before purchase.

Parts can be sourced via Questpair. For the widely-represented Agilent and HP platforms, columns and consumables are stocked more broadly than for less common configurations.

A well-maintained gas chromatograph can run for many years, since the oven, column connections and electronics are robust, but wear items set the real limit. Detector jets can foul, an electron capture detector source is subject to regulatory controls, and a mass spectrometer's pump, source and electron multiplier are the components that need periodic replacement.

Used and refurbished GC systems are listed at lower prices than new, which is the clearest reason the lower end of the price band exists. Where you have to weigh the two, compare the specific listings and confirm what is included, since an autosampler, method files and a working software licence affect the real cost more than the headline figure.

They are listed on Questpair from 14 verified suppliers and distributors across 9 countries. On Questpair, 414 GC systems are listed, of which 99 percent are used.

Lead time and shipping depend on the individual seller, the configuration and its location across the 9 countries represented. The specific listing states what is available, and Questpair specialists respond within one hour to questions about it.

Routine maintenance covers inlet liner and septum changes, column trimming or replacement, leak checks and detector cleaning, with calibration run against reference standards for the compounds you measure. A GC-MS adds tuning and pump service. Questpair does not provide servicing, but parts can be sourced through the platform.

The core gas chromatograph is the central listing for laboratories doing routine separation and quantification, while GC-MS is reached for where compound identity matters, as in metabolomics and lipidomics. Autosamplers are added by labs running large vial trays unattended, and full chromatography systems suit buyers who want the data station and sample handling bundled rather than assembled.

Agilent and its earlier HP-badged instruments make up a large part of the catalogue, with Varian and Thermo Scientific also well represented. A well-represented platform usually means a shallower learning curve, easier comparison between listings of the same series, and a steadier supply of the columns and fittings a chromatograph consumes.

Price tracks the detector count, the presence of mass spectrometry and the age of the data system more than the brand badge. A bench chromatograph with a single detector sits at the lower end, while a complete GC-MS with autosampler and data system carries the top of the band from EUR 40 to EUR 64.567.