Rapid determination of sulfur in steel by electrolytic dissolution – inductively coupled plasma atomic emission spectrometry

Abstract

A rapid determination of sulfur in steel by inductively coupled plasma atomic emission spectrometry (ICP-AES) following an electrolytic dissolution of a solid sample was developed. A solid sample was directly electrolyzed in an electrolysis cell and the resulting electrolyte was on-line introduced into an ICP-AES. The emission intensities obtained by ICP-AES were in linear proportion to the sulfur content in steel. When a sample was electrolyzed with 6 M HCl as electrolyte, the emission intensities of sulfur were much higher than those obtained by measuring standard solutions containing sulfate ions. It suggested that sulfur in the electrolyte solution was in the form of H 2S and introduced into the Ar plasma as H 2S gas which evaporated from the electrolyte solution during nebulization in a spray chamber. Sulfur in steel was determined at concentration levels of 25 μg g −1 with a relative standard deviation of 3.5%. A sample can be analyzed within 60 s. The detection limit (3 σ) of sulfur in steel is 0.6 μg g −1. It was found that large amounts of copper in steel interfered with the sulfur measurement in this analytical system. However, the influence of copper was reduced by using 12 M HCl as electrolyte solutions so that steel samples containing copper in sub% level could be analyzed in the present analytical system.