Flame Spectrophotometric Determination of Iron in Siliceous Materials

Abstract

This investigation describes the application of the Beckman Model DU flame spectrophotometer to the rapid determination of iron in siliceous materials such as alumina refractories and limestone. The arc emission line at 386.0 mg was used to measure the iron radiation.Cobalt was incorporated in the samples in order that the cobalt 387.1-mg arc line could serve as an internal standard. An oxyacetylene flame was the excitation source.The radiative interference of many elements normally associated with iron in siliceous samples could be corrected by using an internal standard. None of the alkalies or alkaline earths offered interference when present in the amounts usually encountered, and large concentrations of aluminum can be tolerated.Magnesium offers serious interference, and when present, the separation of iron as the hydrous oxide is necessary. The optimum concentration range for iron is between 25 and 200 p.p.m. The standard deviation from the mean of replicate samples is approximately 3%. The method has been successfully applied to limestone and several varieties of alumina refractories.

Ferrous Metallurgy

“…The rotating electrode method for spectrographic analysis of slag has been used with cuprous oxide or cobalt nitrate as internal standards (15). For determination of calcium (158) and iron (40) in slags, flame photometry has been used. Titration with (ethylenedinitrilo) tetraacetic acid has been adapted to determination of magnesium (56) and calcium (170).…”

Application of Organic Solvent Extraction to Flame Specrophotometry

“…THE present investigation resulted from the need for a faster method for the flame spectrophotometric determination of iron. In a preceding study a considerable number of elements were found either to interfere directly or to affect the luminescence from the 372.0-, 373.7-, 374.7-, or 386.0-mg flame emission lines of iron (5). Manganese emits a series of weak bands in the region 363 to 400 mg, and magnesium possesses three intense band systems whose heads appear at 372, 375, and 385 mg.…”

“…Sensitivity control, turns from clockwise limit Flame Spectra of Iron. The major flame emission lines of iron are shown in Figure 1, taken from the work of Dean and Burger (5). Of these iron lines, the 372.0-and 386.0-mu lines are the stronger with the 372.0-mu line being the most intense.…”