Influence of Manganese on Emission Spectrochemical Analysis of Niobium in Steel; Interference for Nb II 3194.977 Å

In analyzing niobium in low alloy steel with an emission spectrochemical technique using Nb II 3194.977 Å as an analytical line, it was found that higher experimental values were obtained in spite of the absence of known interference line. The values of 0.004% to 0.007% were, for example, found in spite of the absence of niobium in the steel samples. Studying the cause, we found the following facts ; (1) The precision (σd) was low for the steel sample containing much manganese. (2) A spectral line of manganese is present at the wavelength position of about 3194.87 Å in the vicinity of Nb II 3194.977 Å. (3) The interference can be corrected by the following formula; ΔNb(%)=0.0034×Mn(%)−0.0020 (Mn>0.80%)