pH standardization for phosphorus-31 magnetic resonance heart spectroscopy at different temperatures.

Intracellular pH typically is measured by NMR using the calibrated chemical shift of the inorganic phosphate peak in phosphorus-31 spectra. Heart spectroscopy experiments often require measurements of intracellular pH at temperatures from 5 to 37 degrees C. This paper provides NMR pH calibrations for this range of temperatures, a summary of calibration data reported to date, and a discussion of the factors influencing pH standardization.