carbon 13

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car·bon 13 (13C),

A stable natural isotope, 1.1% of natural carbon.
References in periodicals archive ?
The percentage of carbon 13 in the microfossils was indicative of material produced by biological processes.
Three independent methods, deuterium NMR, carbon 13 NMR and differential scanning calorimetry, can be used by the same researchers on the same samples of food to accurately measure the mobility of water and solids and to predict microbial growth.
For example, carbon 13 is a heavier (and rare) version of the most common type of carbon, called carbon 12.
The highest resolution mass spectrometer ever flown, ROSINA will measure the isotopes Carbon 12 and Carbon 13, which differ by a single neutron, and are used in carbon dating to determine the ages of organisms.
The Carbon 12 to Carbon 13 ratio in a comet tells us about the material that was present in the dense interstellar medium that formed our Sun.
The urea in Pranactin, however, is composed of a form of carbon called carbon 13, which is not commonly found in breath.
Both sets of cores also show similar changes in carbon 13 through time, indicating that the changes in carbon isotopes occurred worldwide and oxygen levels throughout the atmosphere were high.
The tests are based on the use of carbon 13 (13c), a stable, nonradioactive isotope of carbon that comprises about 1 percent of the carbon in nature.
When microbes degrade contaminants, they prefer the lighter isotope carbon 12 over the heavier isotope carbon 13.