Abstract: Soid complex of Gd^3- with 2, 3-dihydroxy-p-xylylenf diaminotetraacetic acid (DPTA) was synthesized. Studies have been performed in which the above-mentioned complex was utilized as water-soluble paramagnetic relaxation reagent for ¹³C NMR spectrometry. Model compounds with which the reagent is effective include threonine, cysteine, arginine, histidine, tryptophan and ascorbic acid. It was shown that the reagent investigated can not only enhance the singal intensities for carbons not attached to hydrogen, but also suppress the nuclear Overhauser effect (NOE) for protonated carbons. Carbons-13 spin-lattice relaxation times (T₁) of the arginine acid in the presence or absence of the relaxation reagents were measured. The results show that Gd-DPTA is more effective than Gd-DTPA as a carbon-13 relaxation reagent.

Key words: ¹³C NMR, Relaxation reagent