Today, most GC columns are fused silica capillaries with an inner diameter of 100–320 micrometres (0.0039–0.0126 in) and a length of 5–60 metres (16–197 ft).

[8] Martin and another one of their colleagues, Richard Synge, with whom he shared the 1952 Nobel Prize in Chemistry, had noted in an earlier paper[9] that chromatography might also be used to separate gases.

Stig Claesson of Uppsala University published in 1946 his work on a charcoal column that also used mercury.

He set up a simple glass column filled with starch and successfully separated bromine and iodine using nitrogen as the carrier gas.

[10] Early gas chromatography used packed columns, made of block 1–5 m long, 1–5 mm diameter, and filled with particles.

However, the price of helium has gone up considerably over recent years, causing an increasing number of chromatographers to switch to hydrogen gas.

[4] FIDs cannot detect water or carbon dioxide which make them ideal for environmental organic analyte analysis.

[4][13] When analyte molecules elute from the column, mixed with carrier gas, the thermal conductivity decreases while there is an increase in filament temperature and resistivity resulting in fluctuations in voltage ultimately causing a detector response.

[4][13] This detector works only for organic / hydrocarbon containing compounds due to the ability of the carbons to form cations and electrons upon pyrolysis which generates a current between the electrodes.

FIDs have low detection limits (a few picograms per second) but they are unable to generate ions from carbonyl containing carbons.

For this reason AFD does not suffer the "fatigue" of the NPD, but provides a constant sensitivity over long period of time.

In addition, when alkali ions are not added to the flame, AFD operates like a standard FID.

[13] The plasma causes the analyte sample to decompose and certain elements generate an atomic emission spectra.

Dry electrolytic conductivity detector (DELCD) uses an air phase and high temperature (v. Coulsen) to measure chlorinated compounds.

Mass spectrometer (MS), also called GC-MS; highly effective and sensitive, even in a small quantity of sample.

[citation needed] Some GC-MS-NMR are connected to an infrared spectrophotometer which acts as a backup detector.

Most chemical species absorb and have unique gas phase absorption cross sections in the approximately 120–240 nm VUV wavelength range monitored.

Where absorption cross sections are known for analytes, the VUV detector is capable of absolute determination (without calibration) of the number of molecules present in the flow cell in the absence of chemical interferences.

[15] Olfactometric detector, also called GC-O, uses a human assessor to analyse the odour activity of compounds.

The purity of the carrier gas is also frequently determined by the detector, though the level of sensitivity needed can also play a significant role.

The linear velocity will be implemented by means of the carrier gas flow rate, with regards to the inner diameter of the column.

The relation between flow rate and inlet pressure is calculated with Poiseuille's equation for compressible fluids.

[4] The choice of inlet type and injection technique depends on if the sample is in liquid, gas, adsorbed, or solid form, and on whether a solvent matrix is present that has to be vaporized.

Some general requirements which a good injection technique should fulfill are that it should be possible to obtain the column's optimum separation efficiency, it should allow accurate and reproducible injections of small amounts of representative samples, it should induce no change in sample composition, it should not exhibit discrimination based on differences in boiling point, polarity, concentration or thermal/catalytic stability, and it should be applicable for trace analysis as well as for undiluted samples.

However, the faster a sample moves through the column, the less it interacts with the stationary phase, and the less the analytes are separated.

However, in most modern applications, the GC is connected to a mass spectrometer or similar detector that is capable of identifying the analytes represented by the peaks.

By calculating the area of the peak using the mathematical function of integration, the concentration of an analyte in the original sample can be determined.

Various temperature programs can be used to make the readings more meaningful; for example to differentiate between substances that behave similarly during the GC process.

In practical courses at colleges, students sometimes get acquainted to the GC by studying the contents of lavender oil or measuring the ethylene that is secreted by Nicotiana benthamiana plants after artificially injuring their leaves.

Disciplines as diverse as solid drug dose (pre-consumption form) identification and quantification, arson investigation, paint chip analysis, and toxicology cases, employ GC to identify and quantify various biological specimens and crime-scene evidence.