Fluorimetric determination of operational pH in 1,4-dioxane-water solutions

✍ Scribed by Robert W. Townsend; Stephen G. Schulman

• Publisher: Elsevier Science
• Year: 1992
• Tongue: English
• Weight: 392 KB
• Volume: 269
• Category: Article
• ISSN: 0003-2670
• DOI: 10.1016/0003-2670(92)85410-8

✦ Synopsis

2-Hydroxyblphenyl demonstrates proton transfer m the lowest excited smglet state m 1,4-dloxane-water mixtures The dlssoclatlon reaction of the directly excited neutral molecule IS strongly solvent dependent and independent of solutton acldlty The reprotonation of the coqugate base, however, depends predommantly on the acidity of the solution and on the bulk dielectric constant of the solvent A linear relationship between the ratlo of the relative fluorescence efficlencles of t-hydroxyblphenyl and Its conjugate base, and the hydrogen ion concentration IS obtained only if proper Brgnsted actlvlty factors are included m the relationship These factors can be calculated from electrostatics and are simple powers of the actlvlty coefficients which would be derived from Debye-Huckel theory and which are aecessaly to convert the formal hydrogen ion concentration to hydrogen ion actlvlty Using this approach it IS possible to calculate pH from hydrogen ion concentration m dloxane-water solutions, contammg mole fractions of up to 0 1 of the orgamc component