I’m just going to leave this here, for the next time I (or anyone else) want to determine the in-tube concentration of an NMR sample.[1,2]
|Solvent||[Residual] in mM|
Values are derived from this formula:
x = the posted deuterium purity (ie. “99.8%” CDCl3)
y= number of hydrogen/deterium atoms per molecule.
d = density of the deutero solvent.
MW for residual solvent (ex. CHD3O for methanol)
 Low concentration samples can be calculated by using the 13C satellite bands, which are 1/200 the concentration of the standard residual peak.
 For water, rinse the NMR tube, vial, etc. with D2O prior to dissolving your sample.