title: Spectrophotometric determination of trace levels of atmospheric ammonia by conversion into indophenol and extraction with quaternary ammonium salts.
abstract: Indophenol, produced in proportion to the amount of ammonia present, can be quantitatively extracted into chloroform as an ion-pair with tetradodecylammonium (TDA(+)) bromide and determined by spectrophotometry. The molar absorptivity of the indophenol-TDA(+) complex is 2.5 x 10(4) 1.mole(-1).cm(-1) (maximum absorption at 653 nm), which is 25% greater than that for the indophenol-TDA(+) complex in aqueous medium. This procedure is applicable to determination of mul/m(3) levels of atmospheric ammonia, with 1-hr sampling periods.
authors.affiliation: Department of Applied Chemistry, Faculty of Science and Technology, Keio University, Hiyoshi, Yokohama 223, Japan.
authors.forename: N
authors.initials: N
authors.lastname: Yamamoto
authors.forename: N
authors.initials: N
authors.lastname: Kasahara
authors.forename: T
authors.initials: T
authors.lastname: Shirai