In chemistry, a precursor is a compound that participates in the chemical reaction that produces another compound. In biochemistry, the term "precursor" is used more specifically to refer to a chemical compound preceding another in a metabolic pathway. In 1988, the United Nations Convention against Illicit Traffic in Narcotic Drugs and Psychotropic Substances introduced detailed provisions and requirements relating the control of precursors used to produce drugs of abuse. In Europe the Regulation (EC) No. 273/2004 of the European Parliament and of the Council on drug precursors was adopted on 11 February 2004. On 15 January 2013 the Regulation (EU) No. 98/2013 of the European Parliament and of the Council on the marketing and use of explosives precursors was adopted. Raman spectroscopy has been successfully tested to detect explosives and their precursors. 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.
^Trace detection of explosives and their precursors by surface enhanced Raman spectroscopy. S. Almaviva, S. Botti, L. Cantarini, A. Palucci, A. Puiu, A. Rufoloni, L. Landstrom,F.S. Romolo, Proceedings of SPIE - The International Society for Optical Engineering, Article number 854602, Optics and Photonics for Counterterrorism, Crime Fighting, and Defence VIII; Edinburgh; United Kingdom (2012) Code 96354.
^S. Mengali, D. Luciani, R. Viola, N. Liberatore, S. Zampolli, I. Elmi, G. Cardinali, A. Poggi, E. Dalcanale, E. Biavardi, P. Esseiva, O. Delemont, F. Bonadio, and F.S. Romolo, Toward street detection of amphetamines. SPIE Newsroom (2013).