1. Introduction. Currently, chromatography has played an irreplaceable role in separation science 1, which is one of the most widely used techniques in the fields of environmental monitoring, food safety, and drug analysis. Due to the outstanding advantages of high sample loading capacity, excellent efficiency and adjustable capacity. selectivity, gas chromatography GC or GLC is an analytical technique commonly used as part of numerous research and industrial research facilities for quality control and also the identification and quantification of components in a mixture. GC is also used as a technique as part of numerous environmental and forensic laboratories, as it includes Summary. Modern gas chromatography (GC) was invented by Martin and James, 1 and has become one of the most important and widely applied analytical techniques in modern chemistry. This historical summary describes the main milestones in the development of GC, especially in column technology, detection and sample introduction. The intent of this article is to review and discuss the various steps involved in QA method development and validation. Gas chromatography is a sensitive, precise and reproducible technique.