Indirect spectrophotometric determination of thiocyanate by extraction as bisthiocyanatobisquinolinemercury(II) complex and its ligand substitution reaction with dithizone.
Thiocyanate forms with mercury(II) in the presence of quinoline a mixed-ligand mercury(II) complex, bisthiocyanatobisquinolinemercury(II), and is extracted into chloroform. This mixed-ligand complex is treated with dithizone and forms the bisdithizonatomercury(II) complex. Maximum and constant absorbance of the dithizone complex is obtained when thiocyanate is extracted at pH 5.1-6.5, and Beer's law is obeyed at 498 nm, where the difference in absorbance between the dithizone complex and dithizone is largest. Chloride, bromide, iodide, cyanide and large amounts of ammonium and copper(II) ions interfere.
Einaga
H
H
National Institute for Researches in Inorganic Materials, Sakura-mura, Niihari-gun, Ibaraki-ken, Japan.
Ishii
H
H
Iwasaki
I
I