title: High-acidity determination in salt-containing acids by optical sensors. The scope of a dual-transducer approach and the Hammett acidity function.
abstract: A dual-transducer approach based on sol-gel optical sensors was recently reported to measure acid and salt concentrations, C(acid) and C(salt), in concentrated aqueous LiCl-HCl, CaCl2-HCl, and AlCl3-HCl solutions (C(acid) at 5-6 M; C(salt) < or = 2 M). The scope of this new approach has been studied in salt-containing HCl solutions with C(acid) at 2-9 M, and factors that influence sensor responses and accuracy have been investigated. A linear relationship between (deltaA/deltaC(salt))C(acid) and (dA/dC(acid))C(salt)=0, which is the basis of this dual-transducer approach, was found to lead to an empirical linear relationship between (deltaH0)C(acid) and (deltaC(salt))C(acid) (H0: Hammett acidity function of the indicator encapsulated in the sensor).
authors.affiliation: Department of Chemistry, The University of Tennessee, Knoxville 37996-1600, USA.
authors.forename: T Andrew
authors.initials: TA
authors.lastname: Canada
authors.forename: Leonardo R
authors.initials: LR
authors.lastname: Allain
authors.forename: David B
authors.initials: DB
authors.lastname: Beach
authors.forename: Ziling
authors.initials: Z
authors.lastname: Xue