Determination of Trace Amounts of Antimony and Boron in High-Purity Iron and Steel by Isotope Dilution/Inductively Coupled Plasma Mass Spectrometry

Abstract

The highly sensitive and precise determination method for trace amounts of Sb and B in high-purity iron and steel has been established by the isotope dilution/Inductively coupled plasma mass spectrometry. For the determination of Sb, the iron matrix was separated by anion-exchange chromatography using Dowex I-X8 in hydrofluoric acid solution, and the isotope ratio (¹²¹Sb/¹²³Sb) of the HNO₃/H₂O₂ eluate was measured by ICP-MS . The isobaric interference of ¹²³Te was corrected by subtracting the intensity of ¹²³Te obtained by the relative intensity of ¹²³Te and ¹²⁵Te. For the determination of B, after the treatment of sulfuric acid-phosphoric acid fuming for the complete decomposition of boron nitride, B was separated by the anion-exchange chromatography using Amberlite IRA-743 at pH 8. The CyDTA was added to prevent the hydrolysis of iron. The isotope ratio (¹¹B/¹⁰B) of the HCl eluate was measured by ICP-MS . By these methods, Sb and B in the range of \\microgram/g to sub-\\microgram/g could be determined with good precision. The limit of detection is 5.8 ng/g for Sb and 16 ng/g for B in steel.