A Gas Chromatograph (GC) separates and measures volatile compounds. It uses simple gas chromatography instrumentation. A carrier gas moves the sample through a GC column. A detector reads the signal. You get clear retention time in GC data. The system works well for volatile organic compound analysis (VOC). Many fields use GC: quality control, petrochemicals, environment, pharma, and forensics. It is fast, accurate, and sensitive.