.
(Or the importance of traces)
By Camila Monroe
Why do dogs
detect smells?
• About 40 times more receptors
than humans;
• More receptors = ability to smell
traces;
• “The second nose”: Jacobson’s
Organ
• We see, they smell
• Ex.: Stew
• Sniffing Vs. Inhaling
• Video
Olfactory
System: Humans
Olfactory
System: Dogs
Detecting
drugs
1.Cocaine
2.Heroine
3.Other drugs
Cocaine
• Two esters linkage
Hydrolysis of
Ester Linkages
in Cocaine
• H20 and H3O+ molecules in the air
• (Very) microscale
• Bags with microscopic leaks
• More humid environments = easier detection
• Four products after decomposition
Mechanism of
Hydrolysis of
Cocaine
1) Protonation of carbonyl
Mechanism of
Hydrolysis of
Cocaine
2) Nucleophilic attack/deprotonation
hemiacetal
Final step
3) Formation of methanol, carboxylic acid and third product
Formation of
benzoic acid
Reaction of
products
3) Fisher esterification of benzoic acid by methanol
Reaction of
products
Overall
reaction
Heroin
• Decomposition releases acetic acid vapors
• Production from morphine generates acetic acid
Acetylation
of Hydroxyl
Groups
• Morphine and acetic acid as reagents
• Esterification
• The most impure, the easiest to detect
Other Drugs…
and money!
• Other drugs: marijuana, ecstasy and etc
• Laundering money smells too!
• Combination of hundreds or thousands of compounds
• No isolated compounds (theory)
• “Funnel of odors”
Detecting
bombs and
explosives
1.TNT
2.C-4 explosives
TNT
• Cheap explosive 3-nitrotoluene
• Chemical reaction of explosion:
• 2 C7H5N3O6 ➞ 3N2+ 5H2O + 7 CO + 7C
• Dogs better than metal detector
DNT
• Dogs detect DNT (unreacted byproduct)
• Production of TNT generates 2,4-dinitrotoluene (DNT), an impurity
• Chemical reaction: nitration
Nitration of
Toluene
• Ortho, para and meta additions: DNT major intermediary product
C-4
• Stable explosive used in bombs
• Major component:
1,3,5-Trinitroperhydro-1,3,5-triazine (RDX)
91%
Detection of
C-4 Purifier
• Cyclohexanone
• Oil used in production of C-4
• Theory: Cyclohexanone to isolate oil
• Not much data on fabrication of C-4 (obviously!)
Beyond Crimes
• Bedbugs scent: volatile aldehydes;
• Missing people and cadavers: “passing time sense”
• Dogs smell stage zero cancer: still a mystery;
Questions?
Bibliography
•
“Acid Rain: Do you need to start wearing a rain hat?” (02 Dec. 2016). USGS. https://water.usgs.gov/edu/acidrain.html
•
Akhavan, J. 2004. The Chemistry of Explosives, 2nd edition. Cambridge, UK: The Royal Society of Chemistry. ISBN 0854046402
•
Baggaley, K. (01 Dec. 2016). “To find drugs and explosives, scientists take cues from dog noses.” PopSci.com, Popular Science.
http://www.popsci.com/sniffing-like-dog-gives-chemical-detectors-boost
•
Birnbaum, M. (12 Jun. 2014). “What the Dog Nose Knows.” ModernFarmer.com. http://modernfarmer.com/2014/06/dog-nose-knows/
•
“Dog bite liability (02 May 2012). SaucyAgency.com. http://soucyagency.com/blog/wp-content/uploads/2012/05/shutterstock_57612025.jpg
•
Esteve-Nunez, A. et al. (Sep. 2001). “Biological Degradation of 2,4,6-Trinitrotoluene.” Microbiol Mol Biol Rev. 2001 Sep; 65(3): 335–352. DOI:
10.1128/MMBR.65.3.335-352.2001
•
Karukstis, K., and Hecke, G. (2003). “Chemistry Connections,” 2nd ed. London: Academic Press. Page 176.
•
Lewis, V. R. et al. (01 Jul. 2013). “Researchers combat resurgence of bed bug in behavioral studies and monitor trials.” California Agriculture
67(3):172-178. DOI: 10.3733/ca.v067n03p172
•
Mesloh, C. (02 Nov. 2000). “Scent as Forensic Evidence and its Relationship to the Law Enforcement Canine.” University of Central Florida.
https://www.scribd.com/doc/257336640/Scent-as-Forensic-Evidence-and-its-Relationship-to-the-Law-Enforcement-Canine
•
Rice, S., and Koziel, J.A. (10 Dec. 2015). “Characterizing the Smell of Marijuana by Odor Impact of Volatile Compounds: An Application of
Simultaneous Chemical and Sensory Analysis.” PLOS One. https://doi.org/10.1371/journal.pone.0144160
•
Smith, J. (2017). “Organic chemistry,” 5th ed. New York: McGraw-Hill Education.
•
Smith, T. J. (23 Jul. 2014). “Can dogs smell cancer?” CompanionTraining.com. http://companiontraining.com/can-dogs-smell-cancer/
•
“Tasting, Smelling, and Touching.” (n/d) Introduction to Psychology, Open Libraries – University of Minnesota.
http://open.lib.umn.edu/intropsyc/chapter/4-4-tasting-smelling-and-touching/
•
Vos, S. (Apr. 2008). “Sniffing Landmines.” ChemMatters – American Chemistry Association.
https://www.acs.org/content/dam/acsorg/education/resources/highschool/chemmatters/gc-sniffinglandmines.pdf?_ga=1.60732013.1354031280.1476945196
•
W-dog.net (n/d). https://w-dog.net/wallpaper/dog-black-and-white-face-view-surprised-of-interest/id/264139/