Justin Yat Cheong Lau1,2, Albert P. Chen3, Jianfeng Zhu4, Gang Wu4, Charles H. Cunningham1,2
1Department of Medical Biophysics, University of Toronto, Toronto, Ontario, Canada; 2Imaging Research, Sunnybrook Health Sciences Centre, Toronto, Ontario, Canada; 3GE Healthcare, Toronto, Ontario, Canada; 4Department of Chemistry, Queen's University, Kingston, Ontario, Canada
A current challenge with tracking C1 polarization by selective small tip angle excitation of C2 in 1,2-[13C]2-pyruvate is the observed evolution of the C2 doublet beyond AB asymmetry. We hypothesize that cross coupling between the dipolar field and chemical shift anisotropy (CSA) may, at least in part, be responsible for this behaviour. This study shows that solution pH has an effect on the relaxation mechanism that currently interferes with polarization measurement using C2 asymmetry of 1,2-[13C]2-pyruvate, suggesting that the C2 CSA of the protonated form may be less effective at coupling with the dipolar field.