Gas Chromatography (GC) can be used to separate and analyze a variety of compounds, especially volatile and semi-volatile organic compounds. The following are some of the items that can be detected by gas chromatography.

Organic compounds such as alkanes, aromatic hydrocarbons, alcohols, aldehydes, ketones, esters, acids, etc.
Gases (e.g. oxygen, nitrogen, carbon dioxide, hydrogen, etc.)
Inorganic gases such as ammonia, chlorine, sulfur dioxide, etc.
Flavors and food additives
Drugs and narcotics
Environmental pollutants (e.g., volatile organic compounds, benzene, volatile gases, etc.)
Biomolecules (e.g. fatty acids, amino acids, hormones, etc.)
Petrochemicals (e.g., oils, paraffins, resins, etc.)
Nutrients in food (e.g. fats, proteins, sugars, etc.)
Components in cosmetics
In conclusion, gas chromatography is an analytical instrument widely used in chemistry, biology, environmental science, food science and other fields, and can detect a wide range of items.