[Study and determination of trace Fe (III) with resin-phase spectrophotometry in Mongolian medicine]

Under the buffer medium of HAc-NaAc of pH = 6.00, Fe(III) and 4-(5-chloro-2-pyridylazo)-1, 3-Diaminobenzene form a colored complex which can be quantitatively absorbed on the strong acid cation exchange resin, and the amount of trace Fe(III) is determined by spectrophotometry. The maximum absorption wavelength is at 540 nm, the apparent molor absorptivity is 1.35 x 10(5) L.mol-1.cm-1. The Beer's law is obeyed in the range of 0-18 micrograms.25 mL-1 for Fe(III). The proposed method has been applied to the determination of trace Fe(III) in mongolian medicine with satisfactory results.