1-(2'-AMINO ARYL)-4,4,6-TRIMETHYL-1,4,5,6-TETRA HYDRO-6-HYDROXY PYRIMIDINE-2(3H) THIONE (HPT) AS A LIGAND FOR THE EXTRACTION AND SPECTROPHOTOMETRIC DETERMINATION OF FE(III)

The optimum conditions for the extractive-spectrophotometric determina tion of Fe(III) with 1-(2'-Amino aryl)-4,4,6-trimethyl-1,4,5,6-tetra h ydro-6-hydroxy pyrimidine-2(3H) thione(HPT)-I,II and III have been est ablished. Fe(III) reacts with this reagent at pH 1.8 - 2.2 to form an uncharged 1:2 (metal-to-ligand) complex, which can be extracted with c hloroform. The coloured system is stable for 24 hrs. The molar absorpt ivities in the CHCl3 phase for HPT-(I) and (III) are 2.2x10(3)L.mol(1) .cm(-1), while for HPT-(II) it is 6.7x10(2) L . mo(-1). cm(-1) at the absorption maximum 460 nm. The calibration graph is linear for 5.6-22. 4 mu g of Fe(III) in 10 mL CHCl3. The proposed method has bren applied for the determination of iron in alloy and in the medicinal plants.