Fig. 3: PHIP-X hyperpolarized 13C3-lactic acid (LA).
From: Nuclear spin polarization of lactic acid via exchange of parahydrogen-polarized protons
a Strong 13C hyperpolarization was observed on 2- and 3-13C lactic acid when the polarization was transferred from the methyl-1H to the methyl-13C using SOT1 (green). No 13C signal enhancement was apparent when the transfer was attempted from the labile proton using SOT2. As reference, 1000 scans of the sample after the PHIP-X experiment were acquired in thermal equilibrium and magnified 10-fold for convenience (gray). b Normalized signal enhancements of 2-13C-LA as a function of concentration ratio c1/c(LA), where 1 = propargyl alcohol. The polarization was found to decrease monotonously around a maximum atc1/c(LA) ≈ 3.5. Changing this ratio affects the proton exchange processes between 1 and LA (Fig. 1a–c). Error bars represent the standard deviation respecting the normalization. Experimental details: c(LA) = 39.3 mM,c1 = 17.3–865 mM. After applying 30 bar pH2 for 5 s at BPol0 = 0.05 mT, the solution was shuttled into the 1 T NMR spectrometer where DEPT 135o (139 Hz) was applied 1.5 s after the beginning of the shuttling.
