title: Critical comparison between modified Monier-Williams and electrochemical methods to determine sulfite in aqueous solutions.
abstract: In the present work, known concentration of sulfite aqueous solutions in the presence and absence of gallic acid was measured to corroborate the validity of modified Monier-Williams method. Free and bound-sulfite was estimated by differential pulse voltammetry. To our surprise, the modified Monier-Williams method (also known as aspiration method) showed to be very inaccurate for free-sulfite, although suitable for bound-sulfite determination. The differential pulse approach, using the standard addition method and a correction coefficient, proved to be swift, cheap, and very precise and accurate.
authors.affiliation: Departamento de Química de Los Materiales, Facultad de Química y Biología, Universidad de Santiago de Chile, Estación Central, Santiago 9170022, Chile.
authors.forename: C
authors.initials: C
authors.lastname: Montes
authors.forename: J H
authors.initials: JH
authors.lastname: Vélez
authors.forename: G
authors.initials: G
authors.lastname: Ramírez
authors.forename: M
authors.initials: M
authors.lastname: Isaacs
authors.forename: R
authors.initials: R
authors.lastname: Arce
authors.forename: M J
authors.initials: MJ
authors.lastname: Aguirre
mesh_terms: D055664:Electrochemical Techniques; D012996:Solutions; D013447:Sulfites / Q000032:analysis*; D014867:Water / Q000737:chemistry*
chemical_list: D012996:Solutions; D013447:Sulfites; D014867:Water