This book covers all the major Applications of a relatively new technique named Gas chromatography-Mass Spectrometry Which is a Hyphenated technique used to detect Various Components which was not Possible earlier due to various problems. By using this technique researches have been done in Various Fields like in petrochemical analysis, Geochemical analysis, environmental analysis and now even it is used these days in solving Various Court cases and forensics Ultimately after going through this it can be rightly said that this technique is "GOLD STANDARD FOR DETECTION"