Food adulteration can be determined by measuring the ratio of 2H vs. 1H atoms at the site-specific portion of an analyte. It is done by measuring both spectra and then calculating the ratio. Sometimes an additional ratio of 13C vs. 12C is determined by NMR, also to check for adulteration. What I don't understand here is:
1) how is the quantity of 12C determined, if 12C is NMR inactive?
2) how in the world is 13C quantified by NMR, if carbon spectra are decoupled and thus "unintegrable"??
I'd be grateful if somebody could explain this.