Determination of sulphur in low sulphur steels by isotope dilution thermal ionisation mass spectrometry
Abstract
Total sulphur was determined in chips of six different metallic National Institute of Standards and Technology (NIST) Standard Reference Materials (SRMs) and in four different steel samples from foreign sources by isotope dilution thermal ionisation mass spectrometry (ID-TIMS). This procedure determines the concentration of sulphur with absolute accuracy using enriched 34S as an internal standard. The concentrations of sulphur (µg g–1) found in these SRMs were: SRM 1764, 118.8 ± 2.4; SRM 1765, 37.8 ± 1.1; SRM 1766, 23.5 ± 1.5; SRM 1767, 90.84 ± 0.96; SRM 132b (Tool steel), 30.27 ± 0.78; and SRM C2423 (Ductile iron), 6.4 ± 1.23. The uncertainties are 95% confidence intervals and include all known sources of random and systematic error. These standards are useful for calibrating analytical techniques that rely on external standards for the determination of sulphur in steels.