Gas chromatography ("GC") and mass spectrometry ("MS") make an effective combination for chemical analysis. This article serves to demonstrate tools for an effective attack or defence of GC/MS evidence. The GC device is generally a reliable analytical instrument.The GC instrument is effective in separating compounds into their various components. However, the GC instrument cannot be used for reliable identification of specific substances. The MS instrument provides specific results but produces uncertain qualitative results. When an analyst uses the GC instrument to separate compounds before analysis with an MS instrument, a complementary relationship exists. The technician has access to both the retention times and mass spectral data. Many scientists consider GC/MS analysis as a tool for conclusive proof of identity. GC/MS analysis, where the effluent to the GC instrument is the feed to the MS instrument, is in wide use for confirmation testing of substances. Drug testing, manufacturing quality control and environmental testing are some typical uses
