# Where can I find ranges of isotope abundances?

I'd like to know how much stable isotopes like $\ce{^{13}C}$, $\ce{^2H}$, $\ce{^{17}O}$ and $\ce{^{18}O}$ deviate from their natural abundances in the earth's crust among all possible compounds we may come across, especially organic molecules. I'd like to know a rough minimum and maximum percentage of such isotopes that a given compound is likely to contain, and if possible how likely it is to contain such a percentage. It might be really good to have a histogram showing how common compounds with different percentages of such isotopes are. Does anyone know where I could find such data?

I am aware of this range diagram about $\ce{^{81}Br}$ that appeared in the recurrent (open access) IUPAC recommendations of atomic weights in Pure and Applied Chemistry:

(source: doi 10.1351/PAC-REP-13-03-02)

which cites data of a publication in Environmental Chemistry extending a little to $\ce{^{37}Cl}$ (doi 10.1071/EN10090, open access), too.

Even if the elder (2000) IUPAC compilation in the same journal includes a graphical representation of the range in occurrence of $\ce{^2H}$ as known at this time:

(source: doi 10.1351/pac200375060683, open access)

it may be worth to read more in detail, as -- in contrast to the 2011 edition (32 pages) -- the 2000 edition (120 pages) includes a dedicated section "Isotope fractionation from natural processes" and "Element-by-element review of the standard atomic weights" for a detailed view.

Otherwise, if you were "just" interested in an overall overview of isotopes, their masses and their percentage of occurrence, NIST has a searchable dedicated database here.

After looking through the sources from the gratefully acknowledged Buttonwood's answer, I also came across CIAAW, which seems to have some of the best available data for the natural isotope abundance ranges of elements like $$\ce{C}$$, $$\ce{H}$$, $$\ce{N}$$, $$\ce{O}$$, and $$\ce{Cl}$$. It is based on IUPAC Technical Report 2013 [1].

### References

1. Meija, J.; Coplen, T. B.; Berglund, M.; Brand, W. A.; De, B. P.; Gröning, M.; Holden, N. E.; Irrgeher, J.; Loss, R. D.; Walczyk, T.; et al. Isotopic Compositions of the Elements 2013 (IUPAC Technical Report). Pure and Applied Chemistry 2016, 88 (3), 293–306. https://doi.org/10.1515/pac-2015-0503.