This resource is based on three AHRC funded projects that have used GCMS
technology to identify archaeological data that would otherwise not be
visible. The projects show how archaeological knowledge and painstaking
field work are supported by sensitive measurement of ancient biological
molecules and isotope analysis.
Chromatography, mass spectrometry and nuclear isotopes are core parts of
the chemistry and physics curriculum. Archaeology provides a motivating
context for these subjects.
The University of York BioArch facility is a leading user of these
techniques. They have also created resources on mass Spectrometry for the
National STEM eLibrary that can be found here>
The RSC site SpectraSchool also has useful information on spectroscopic techniques including MS.
For teachers only, the details of sample preparation and GC-c-MS (Gas Chromatography Combustion Mass Spectrometry) for carbon and nitrogen isotope ratios are explained in this sample lab report.
collagen-isotope-report.pdf
Careers
Archaeology and archaeological science courses develop skills that are in demand for wider forensic work including crime investigation, environmental studies, agricultural and food science.
Universities offering these courses have this information on their websites.
Assumed knowledge
- Basic atomic structure, isotopes
- Basic appreciation of food chains
- Some familiarity with chromatography
- Some appreciation of organic molecules, enzyme action, electric charge and electromagnetic force on a charged particle.
Delta notation on graphs
Carbon 13 to carbon 12 ratios are plotted using delta notation; δ
13C. The quantities of
13C are very small. It is easier for
scientists to compare them to an internationally agreed standard ratio of
13C to
12C. So if δ
13C = -21 it is 21 parts per thousand less than the international standard. Most δ
13C values are negative. This looks odd, but all it means is that most
13C levels are below the standard. The reference today is a sample held in Vienna.
More information is at http://en.wikipedia.org/wiki/%CE%9413C
This is beyond the school curriculum, bit should be understandable by 16+ students. Variance from a standard gives an immediate measure of whether something is above or below a well known standard. It is much more useful than grappling with absolute values. In other words a δ
13C for you of -2 would be a giveaway that you were a regular at the chippy. -24 would put you in the burger or vegetarian zone.
A very useful presentation is here
https://www.physics.utoronto.ca/students/undergraduate-courses/course-homepages/jpa305h1-310h1/stableisotopes.pdf
Carbon 14 dating- independent student research task
This resource does not include carbon 14 or radiocarbon dating. Radiocarbon dating is well documented elsewhere. Radiocarbon dating can be applied to all biological materials and gives a measurement of age. Like other isotope measurements, it has transformed archaeology. This is an ideal subject for a research project and presentation by students. Students enjoy learning about this concept of half life from the moment at which carbon uptake stops.
There are many useful sites including:
https://c14.arch.ox.ac.uk/embed.php?File=dating.html
and
http://science.howstuffworks.com/environmental/earth/geology/carbon-141.htm
Isotope fractionation
The reason that sea water contains a higher ration of carbon 13 to 14 is process called isotope fractionation. This also occurs with isotopes of oxygen. This is well covered online and would be too much information for this resource.Fractionation of carbon and oxygen isotopes in the environment is well covered in Wikipedia.
Acknowledgements
I would like to thank Professor Naomi Sykes from the University of Nottingham and her colleagues in the Fallow Deer and Chicken research projects
https://www.nottingham.ac.uk/archaeology/research/bioarchaeology/zooarchaeology/fallow-deer.aspx
http://chickenco-op.net/
and also Dr Oliver Craig, Director of York BioArch https://www.york.ac.uk/archaeology/centres-facilites/bioarch/
Both these scientists gave me their time to explain the technical and historical sides need to write this resource as well as proof checking and corrections.
Nick Swift - Author
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