pH detection in biological samples by 1D and 2D 1 H– 31 P NMR

Abstract The chemical shifts of several important endogenous phosphorus compounds under different pH conditions were explored, including adenosine-5′-triphosphate, adenosine-5′-diphosphate, adenosine-5′-monophosphate, phosphorylcholine and phosphorylethanolamine. Their 31 P NMR and 1 H NMR chemical shifts were all pH-sensitive in the similar pH range. Two dimensional (2D) 1 H– 31 P NMR spectra were found helpful to identify these endogenous phosphorus markers in biological samples from rather complicated NMR spectra. Herein, for the first time, a pH sensor based on 2D 1 H– 31 P NMR was established and applied to biological samples analysis with pH values determined in good agreement with those by potentiometric method. Apart from being simple, green, rapid and less sample-consuming, information concerning both the endogenous phosphorus markers and pH status could be attained in a single NMR run, which demonstrated the great potential of this method in rare sample analysis and even disease diagnosis.