title: Do zwitterions contribute to the ionic strength of a solution?
abstract: Capillary electrophoresis has been used to determine whether zwitterions contribute to the ionic strength of a solution, by measuring the mobility of a double-stranded DNA oligomer in cacodylate-buffered solutions containing various concentrations of the ionic salt tetraethylammonium chloride (TEA(+)Cl(-)) or the zwitterion tricine(+/-). The mobility of the DNA decreased as the square root of ionic strength, as expected from the Debye-Hückel-Onsager theory of electrophoresis, when TEA(+)Cl(-) was added to the buffer. However, the mobility was independent of the concentration of added tricine(+/-). Hence, zwitterions do not contribute to the ionic strength of a solution.
authors.affiliation: Department of Biochemistry, University of Iowa, Iowa City, IA 52242, USA.
authors.forename: Earle
authors.initials: E
authors.lastname: Stellwagen
authors.forename: Jason D
authors.initials: JD
authors.lastname: Prantner
authors.forename: Nancy C
authors.initials: NC
authors.lastname: Stellwagen
mesh_terms: D004247:DNA / Q000302:isolation & purification*; D019075:Electrophoresis, Capillary; D005998:Glycine / Q000031:analogs & derivatives* / Q000737:chemistry; D007477:Ions / Q000737:chemistry*; D009994:Osmolar Concentration; D012996:Solutions / Q000737:chemistry; D019789:Tetraethylammonium / Q000737:chemistry
chemical_list: D007477:Ions; D012996:Solutions; D019789:Tetraethylammonium; D004247:DNA; D005998:Glycine; C100184:tricine