US Environmental Protection Agency site that explains GC for those interested in environmental analysis. Assumes some user background in the field. Includes a partial list of EPA Field Methods that utilize GC which may be helpful to those interested in regulatory protocols.
The website is available here .
Further Analytical Methods developed by the Environmental Protection Agency (EPA) for Chromatographic Analysis of Drinking Water can be found at
https://www.epa.gov/dwanalyticalmethods/analytical-methods-developed-epa-analysis-unregulated-contaminants