title: Sensitivity improvement of ammonia determination based on flow-injection indophenol spectrophotometry with manganese(II) ion as a catalyst and analysis of exhaust gas of thermal power plant.
abstract: The sensitivity improvement of a flow-injection spectrophotometric method for the determination of ammonia was examined based on an indophenol blue coloration reaction with salicylate and hypochlorite in the presence of manganese(II) as a reaction promotion catalyst. The optimal conditions for achieving higher sensitivity of ammonia determination were examined using a three-line flow system. The limit of detection corresponding to a signal-to-noise ratio (S/N) of 3 was 0.005 mg l(-1) (approximately equal to 5 ppb) of NH4+. A calibration graph was linear in the range from 5 ppb to 1,000 ppb of ammonium ion. The relative standard deviations (n = 9) for 50 ppb and 100 ppb of ammonium ion were 6.4% and 2.2%, respectively. The proposed method was applied to the determination of ammonia in the exhaust gas of a thermal power plant. Prior to the FIA determination, ammonia in the exhaust gas was absorbed into a boric acid solution; the absorption solution was then analyzed by the proposed FIA.
authors.affiliation: The Chugoku Electric Power Co, Inc Technical Research Center, Higashi-Hiroshima, Japan. 595184@pnet.energia.co.jp
authors.forename: Tomonori
authors.initials: T
authors.lastname: Tsuboi
authors.forename: Yoshio
authors.initials: Y
authors.lastname: Hirano
authors.forename: Yoshinori
authors.initials: Y
authors.lastname: Shibata
authors.forename: Shoji
authors.initials: S
authors.lastname: Motomizu