title: Determination of pH using water protons and chemical exchange dependent saturation transfer (CEST).
abstract: Solution pH was measured using water proton NMR via chemical exchange dependent saturation transfer (CEST) with selected chemical exchange sites. Several useful pH-sensitive proton chemical exchange agents were found: 5,6-dihydrouracil, 5-hydroxytryptophan, and a combination of 5-hydroxytryptophan and 2-imidazolidinethione. A ratiometric approach was developed that permitted pH determinations that were independent of water T(1) or exchange site concentration.
authors.affiliation: Laboratory of Cardiac Energetics, National Heart Lung and Blood Institute, National Institutes of Health, Bethesda, Maryland 20892, USA.
authors.forename: K M
authors.initials: KM
authors.lastname: Ward
authors.forename: R S
authors.initials: RS
authors.lastname: Balaban
mesh_terms: D003287:Contrast Media / Q000737:chemistry / Q000378:metabolism; D005682:Gadolinium / Q000737:chemistry / Q000378:metabolism; D006863:Hydrogen-Ion Concentration; D008279:Magnetic Resonance Imaging / Q000379:methods*; D009682:Magnetic Resonance Spectroscopy / Q000379:methods; D011522:Protons; D014867:Water / Q000737:chemistry
chemical_list: D003287:Contrast Media; D011522:Protons; D014867:Water; D005682:Gadolinium