sentences:  A portable, advanced sensor based on infrared spectroscopy in a hollow fiber matched to a silicon-micromachined fast gas chromatography column can analyze illegal stimulants and precursors with nanogram-level sensitivity.Raman spectroscopy has been successfully tested to detect explosives and their precursors.Technologies able to detect precursors in the environment could contribute to an early location of sites where illegal substances (both explosives and drugs of abuse) are produced.