1a:I[76865,["/_next/static/chunks/d07a36b34c614bac.js","/_next/static/chunks/a439560253821848.js","/_next/static/chunks/992d80515d7f780d.js","/_next/static/chunks/3adfb55b15c8d19c.js","/_next/static/chunks/b642b3e65e2c6231.js","/_next/static/chunks/fc50eca1ad01dc11.js","/_next/static/chunks/afc6bdd59b458409.js","/_next/static/chunks/6448cccc5d968256.js"],"Grid"] 1b:I[17291,["/_next/static/chunks/d07a36b34c614bac.js","/_next/static/chunks/a439560253821848.js","/_next/static/chunks/992d80515d7f780d.js","/_next/static/chunks/3adfb55b15c8d19c.js","/_next/static/chunks/b642b3e65e2c6231.js","/_next/static/chunks/fc50eca1ad01dc11.js","/_next/static/chunks/afc6bdd59b458409.js","/_next/static/chunks/6448cccc5d968256.js"],"GridCol"] 1c:I[34616,["/_next/static/chunks/d07a36b34c614bac.js","/_next/static/chunks/a439560253821848.js","/_next/static/chunks/992d80515d7f780d.js","/_next/static/chunks/3adfb55b15c8d19c.js","/_next/static/chunks/b642b3e65e2c6231.js","/_next/static/chunks/fc50eca1ad01dc11.js","/_next/static/chunks/afc6bdd59b458409.js","/_next/static/chunks/6448cccc5d968256.js"],"Avatar"] 1d:I[32972,["/_next/static/chunks/d07a36b34c614bac.js","/_next/static/chunks/a439560253821848.js","/_next/static/chunks/992d80515d7f780d.js","/_next/static/chunks/3adfb55b15c8d19c.js","/_next/static/chunks/b642b3e65e2c6231.js","/_next/static/chunks/fc50eca1ad01dc11.js","/_next/static/chunks/afc6bdd59b458409.js","/_next/static/chunks/6448cccc5d968256.js"],"default"] 1e:T513,pK_a is an important property of a molecule which impacts many fields, such as drug design, catalysis, reactivity, and environmental toxicity. It is often necessary to measure pK_a in nonaqueous media due to the poor solubility of an analyte in water, for example, many compounds of pharmaceutical interest. Although NMR methods to measure pK_a in water are well established, determining pK_a in organic solvents is laborious and problematic. We present an efficient one-shot method to determine the pK_a of an analyte in an organic solvent in a single measurement. Diffusion of an acid into a basic solution of the analyte and a set of pH indicators establishes a pH gradient in the NMR tube. The chemical shift of a pH sensitive resonance of the analyte and the pH of the solution are then determined simultaneously as a function of position along the pH gradient by recording a chemical shift image of the NMR tube. The pK_a of the analyte is then determined using the Henderson-Hasselbalch equation. The method can be implemented in any laboratory with a gradient equipped NMR high-field spectrometer and is demonstrated for a range of pharmaceutical compounds and inorganic phosphazene bases.

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