Determination of acid dissociation constants of neamine by potentiometric and electrospray mass spectral techniques
EI von Nagy-Felsobuki, None None, Y Baran, GA Lawrance
article (Uluslararası, Hakemli) | Yazar(lar): EI von Nagy-Felsobuki, None None, Y Baran, GA Lawrance | Yıl: 2001 | Dergi/Kurum: STRUCTURAL CHEMISTRY | İndeks: WOS.SCI | Anahtar Kelimeler: stability constants, potentiometric titrations, electrospray ionization, mass spectrometry — Özet: The acid dissociation constants o
The acid dissociation constants of neamine have been measured using potentiometric titrations. The pK(a1), pK(a2), and pK(a3) values of neamine are 6.35 +/- 0.2, 7.73 +/- 0.15, and 8.62 +/- 0.08, respectively. Neamine is readily characterized using positive-ion electrospray ionization-mass spectrometry (ESI-MS). Various protonated species and their solvated ions are mainly observed. Nevertheless, the abundances of the observed speciation over the pH range 5.0-9.8 do not reflect the variation in the bulk solution. Hence, reaction quotients determined from the ESI-MS investigations vary significantly from the pK(a)'s determined from potentiometric titrations, thereby illustrating that care must be taken in determining thermodynamic properties using the former technique.