A very sensitive catalytic spectrophotometric method for the determination of trace amts. of Mn(II) is reported. The determination is based on the decrease of the absorbances of the indicator reaction of Calred (CR) with H2O2 which is catalyzed by Mn(II) with heat in Clark-Lubs buffer solution (pH 9.8). The reaction is first-order in CR or Mn(II) and the apparent activation energy of the catalytic reaction is 115.31 kJ/mol. This method was applied to the determination of trace amts. Mn(II) in human hair and tap water. The coefficient variations are 4.95 and 5.63%, resp.

Key words: SPECTROPHOTOMETRY, SODIUM COMPOUNDS, CATALYSIS, REACTION KINETICS, MANGANESE, HUMAN HAIR, NAPHTHALENE P, TRACE ANALYSIS, NAPHTHALENOL P, SULFONATE