Spectrophotometric determination of fe(iii) with tiron in the presence of cationic surfactant and its application for the determination of iron in al-alloys and cu-based alloys

A sensitive spectrophotometric method for the determination of iron with tiron and a cationic surfactant, cetylpyridinium chloride, at pH 5.6 is reported. The complex is extracted into a chloroform-propan-2-ol (4:1) mixture and shows maximum absorbance at 520 nm. Beer's law is obeyed in the range 1-14 mu g/ml with an average molar absorptivity of 158001 mol(-1) cm(-1). The molar ratio as determined by Job's method for Fe:tiron:CPC is 1:4:3. Interferences by various ions are examined. Zr,Ti and Mo interfere heavily. The method is applied for the determination of iron in Al-based and Cu-based alloys, using appropriate masking agents.