Carbon-13



Carbon-13
General
symbol Carbon-13,13C
Neutrons 7
Protons 6
Nuclide data
Natural abundance 1.109%
Spin +½
Carbon-13 (13C)is a natural, carbon and one of the environmental isotopes. It makes up about 1.1% of all natural carbon on Earth. Pure carbon-13 costs about $700 per gram.[1]

Detection by NMR spectroscopy

Because of its nuclear spin properties, this isotope responds to a 13C NMR spectrum can take from a couple of minutes to hours because many scans have to be summed together in order to have results distinguishable from background noise.

In microorganisms genetically engineered to express the protein on a growth medium with 13C labeled glucose as the only carbon source. In this way proteins with a 13C content of almost 100% can be produced.

Detection by mass spectroscopy

A 12C. Similarly a molecule containing two carbon atoms will be expected to have an M+1 peak of approximately 2.2% of the size of the M peak, as there is double the previous likelihood that a molecule will contain a 13C atom.

In the above the mathematics and chemistry have been simplified, however it can be used effectively to give the number of carbon atoms for small to medium sized organic molecules. In the following formula the result should be rounded to the nearest integer:

C = \frac{100Y}{1.1X}

C = number of C atoms X = amplitude of the M ion peak Y = amplitude of the M+1 ion peak

13C-enriched compounds are used in the research of metabolic processes by means of mass spectroscopy. Such compounds are safe because they are non-radioactive. In addition, 13C is used to quantitate proteins (quantitative SILAC).

See also

  • Carbon
  • Isotope fractionation

References

  1. ^ [1]
 
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