Nitrophenyl pentadienal

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Nitrophenyl pentadienal
Nitrophenyl pentadienal.svg
Preferred IUPAC name
  • 2608-48-2
3D model (JSmol)
  • InChI=1S/C11H9NO3/c13-9-3-1-2-4-10-5-7-11(8-6-10)12(14)15/h1-9H/b3-1+,4-2+
  • c1cc(ccc1/C=C/C=C/C=O)[N+](=O)[O-]
Molar mass 203.197 g·mol−1
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
Infobox references

Nitrophenyl pentadienal, nitrophenylpentadienal, NPPD, or METKA (Russian for "mark") colloquially known as "spy dust",[1] is a chemical compound used as a tagging agent by the KGB during the Cold War Soviet Era. Soviet authorities in Moscow tracked Americans by applying an almost invisible powder to their clothing, cars, doorknobs and other objects. Some other variants of "spy dust" may have contained luminol and would glow under ultraviolet light.[2][3][4]


Spy dust was first discovered in England in the 1930s.[5]

It was first revealed to the Central Intelligence Agency in Moscow in 1963 by Alexander Chrepanov, a KGB walk in.[4]

Spy dust was detected in the Soviet Union in 1970s in tiny quantities.

In 1984, KGB officer Sergei Votontsov (Code name GT/COWL) provided a sample of the substance.[4]

Soviet defector Vitaly Yurchenko confirmed the chemical.[4][6]

In the summer of 1985 the powder began to appear in Moscow in much larger quantities. Concerned about the health effects of the substance, the United States State Department publicly protested to the Soviets. It was later determined that the health threat was low.[7][8][9]

Beginning about 2005-2015, a chemical tracking kit for law enforcement agencies was developed using NPPD.[10] To detect NPPD a 0.1% methanol solution of naphthoresorcinol is added to a swab of the item in question and then concentrated hydrochloric acid is added. The observation of a red color indicates a positive test.[11] Napthoresorcinol was frequently used in early organic chemistry investigations to determine the presence of aldehyde groups in solution; a red adduct is formed in acidic solution.[12]


  1. ^ Burka LT, Sanders JM, Kool CP, Kim YC, Matthews HB (1987). "Absorption and metabolism of 5-(4-nitrophenyl)-2,4-pentadienal (Spydust)". Toxicol Appl Pharmacol. 87 (1): 121–126. doi:10.1016/0041-008x(87)90090-1. PMID 3798448.
  3. ^ Tony Mendez, Bruce Henderson, Spy Dust: Two Masters of Disguise Reveal the Tools and Operations, Page 121.
  4. ^ a b c d Historical Dictionary of Russian and Soviet Intelligence, Page 194.
  5. ^ Steve Mirsky, Radioactive Spy Dust and the Litvinenko Case; Ode To Grad Students, (December 20, 2006).
  6. ^ Spy Dust
  7. ^ KGB Tracking Diplomats With 'Spy Dust,' U.S. Says : Step-up in Agents's Use Protested, Los Angeles Times, August 21, 1985.
  8. ^ Klopman G, Kalos A, Frierson M, Rosenkranz HS (1986). "NPPD (spy dust) is predicted to be a mutagen". Environ Mutagen. 8 (4): 627–30. doi:10.1002/em.2860080413. PMID 3525138.
  9. ^ Marshall, E. (1985). ""Spy Dust" Irritates Diplomats". Science. 229 (4717): 952. doi:10.1126/science.229.4717.952. PMID 17782513.
  10. ^ Development of a field kit for use by non-scientists for chemical tracking using 5-(4-nitrophenyl)-2,4-pentadien-1-al
  11. ^ Suzuki, Shinichi; Ohta, Hikoto; Suzuki, Yasuhiro; Sugita, Ritsuko; Kasamatsu, Masaaki; Mori, Masahito; Nakajima, Hidemitsu (2005). "5-(4-Nitrophenyl)-2,4-pentadien-1-al (NPPD) used as a tracer by nonscientists at a simulated crime scene". Forensic Science International. 152 (1): 29–34. doi:10.1016/j.forsciint.2005.02.026. PMID 15939173.
  12. ^ Naphthoresorcinol (Old-timey tests) Posted by Molecule of the Day on April 8, 2009