语是怎么定义的?用什么做参照标准? The δ13C value is defined as the C-13 isotope concentration in a sample relative to that in the standards. The standard is a particular limestone from the Pee Dee Belemnite fossil (PDB). The value can be expressed by this equation: δ13C = [(13C/12C)sample-(13C/12C)PDB]/[(13C/12C)PDB] You can find more detailed definition, derivation and explanations in any stable isotope textbook.
Thank you very much! I find out that sometime many other standards are used. So how may I know which standard it was used in a paper? Is PDB the default standard? Thanks!
【在 a***a 的大作中提到】 : : 语是怎么定义的?用什么做参照标准? : The δ13C value is defined as the C-13 isotope concentration in a sample : relative to that in the standards. The standard is a particular limestone : from the Pee Dee Belemnite fossil (PDB). The value can be expressed by this : equation: : δ13C = [(13C/12C)sample-(13C/12C)PDB]/[(13C/12C)PDB] : You can find more detailed definition, derivation and explanations in any : stable isotope textbook.
a*a
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Generally, every lab produces its own standards for routine analyses. But all the published data should have been calibrated relative to the international standard (PDB for stable C isotopes).
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【在 t*****a 的大作中提到】 : Thank you very much! : I find out that sometime many other standards are used. : So how may I know which standard it was used in a paper? Is PDB the default : standard? Thanks!