Matrix-precipitation for the Determination of Trace Impurities in High-purity Iron

The present paper describes a facile method for the determination of trace impurities in iron metals. This method is based on the selective removal of the matrix element as hydroxide precipitate followed by the determination of desired trace elements left in the solution. To an iron sample solution were added ethylene glycol bis(2-aminoethyl ether)-N,N,N',N'-tetraacetic acid (EGTA) and diethylenetriamine. The iron(III) matrix was almost completely (>99%) precipitated at pH 9.5, while trace elements [Mn(II), Co(II), Ni(II), Cu(II), Zn(II), Cd(II), and Pb(II)] were left in the solution due to the complexation with EGTA and diethylenetriamine. The sufficient removal of the matrix element and negligible loss of trace elements allowed the sensitive determination at ng g(-1) levels by inductively coupled plasma-mass spectrometry.