in development

Detecting Spoiled Wine with NMR


This is little more than an idea.  It is posted here per chance that it might also spur ideas from others for the development of chemistry instructional materials.

An article in Chemical & Engineering News, March 28, 2005, notes the difficulty of detecting spoiled wine in bottle.  They report that typically wine spoils either by oxidation of the ethanol (the alcohol, CH3CH2OH) converting it to either acetic acid (CH3COOH) or acetaldehyde (CH3CH=O), or by addition of 2,4,6-trichloroanisole (abbreviated as TCA) manufactured by mold in the cork.
CH3CH2OH + 1/2 O2 → CH3CH=O + H2O
Researchers report some success detecting the first kind of spoilage using a non-invasive procedure of nuclear magnetic resonance (abbreviated as NMR) to detect Hydrogen in the acetic acid.

Protons, neutrons, and electrons, the elementary particles inside atoms, each have tiny magnetic fields due to an intrinsic property called spin. (Some atomic nuclei have even numbers of protons and neutrons which pair so their opposing spins cancel leaving no intrinsic magnetic field.)  Atomic nuclei such as the Hydrogen isotope 1H with at least one unpaired proton or neutron, have intrinsic magnetic fields which can align in at least two orientations when placed in an external magnetic field.  These orientations have different energies when in a magnetic field.  A nuclei with one orientation may flip to another alignment provided it gains or loses the precise energy difference between the orientations.  A particle can resonate back and forth between orientations by gaining and losing energy if nudged by a precisely tuned electromagnetic wave.  Thus this is called nuclear magnetic resonance.  Each isotope responds only to oscillating magnetic fields generated at the required unique radio frequency.  Different neighboring atoms can have a tiny but distinguishable effect on this unique frequency provided that the atoms are in a very strong magnetic field.  Apparatus tuned to provide that precisely needed frequency allow those atoms to be remotely detected and mapped.

To better understand the broad explanation above, read about NMR as well as view helpful diagrams and animations at Sheffield Hallam University.


[what is needed here is an activity which helps to understand the process of NMR.]

Communicating technical information such as observations and findings is a skill used by scientists but useful for most others.  If you need course credit, use your observations in your journal to construct a formal report.



to next investigation
to Biochemistry menu
to e-Chemistry menu
to site menu

created 4/3/2005
revised 4/3/2005, & re-numbered
by D Trapp
Mac made