title: Direct solubility determination in optically dense solutions of highly soluble chromophores by the optoacoustic technique: Acidity dependence for Phenol Red.
abstract: The optoacoustic (OA) technique capable for light-absorption measurements in highly concentrated solutions is applied for direct solubility assessment in highly absorbing saturated solutions without any dilution or sample preparation. Maximum solubility of Phenol Red in aqueous solutions at pH>11 is found to be 1.3±0.1 g/L. The experimental dependence of solubility of Phenol Red on solution acidity was obtained with optoacoustic and conventional spectrophotometric measurements. The data from both methods show complementary results. The model of the solubility of Phenol Red on solution acidity describing the experimental dependence is proposed, which cannot be attained at pHs above 7 without the OA-technique.
authors.affiliation: M.V. Lomonosov Moscow State University, Chemistry Department, Leninskie Hills 1/3, 119991, GSP-1, Moscow, Russia. Electronic address: wild9chemist@gmail.com.
authors.forename: M A
authors.initials: MA
authors.lastname: Shishkin
authors.affiliation: M.V. Lomonosov Moscow State University, Chemistry Department, Leninskie Hills 1/3, 119991, GSP-1, Moscow, Russia. Electronic address: dmsvolkov@gmail.com.
authors.forename: D S
authors.initials: DS
authors.lastname: Volkov
authors.affiliation: M.V. Lomonosov Moscow State University, Chemistry Department, Leninskie Hills 1/3, 119991, GSP-1, Moscow, Russia; University of Washington, Department of Bioengineering, Seattle, WA, 98195, USA. Electronic address: ivanp3@u.washington.edu.
authors.forename: I M
authors.initials: IM
authors.lastname: Pelivanov
authors.affiliation: M.V. Lomonosov Moscow State University, Chemistry Department, Leninskie Hills 1/3, 119991, GSP-1, Moscow, Russia. Electronic address: proskurnin@gmail.com.
authors.forename: M A
authors.initials: MA
authors.lastname: Proskurnin
keywords: Highly absorbing solutions; Optical absorption; Optoacoustic technique; Phenol Red; Solubility