The cross-polarization magic angle spinning (CPMAS) C-13 NMR spectra of N-15-enriched 2-phenethylamine as the ammonium salt and adsorbed on an aluminum-exchanged clay are compared with spectra for natural abundance 2-phenethylamine. An important gain in resolution is observed in the beta carbon chemical shift region of the C-13 CPMAS of the N-15-enriched material relative to either the natural abundance material or the C-13-enriched amine. The CPMAS N-15 NMR spectra of N-15-enriched 2-phenethylamine adsorbed on the aluminum-exchanged clay reveal the presence of multiple Bronsted sites for adsorption.