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

The chemical shifts of several important endogenous phosphorus compounds were explored in different pH condition, including adenosine 5′- triphosphate, adenosine-5′-di-phosphate, adenosine-5′-monophosphate, phosphorylcholine and phosphoylethanolamine. Their 31P NMR and 1H NMR chemical shifts were both pH-sensitive in a similar range. 2D 1H-31P NMR spectra were helpful to recognize endogenous phosphorus markers in very complex NMR spectra of biological samples. A pH sensor based on 2D 1H-31P NMR was established and applied. The measured pH values agreed well with the results by potentiometric method.154