Determination of sulfur in steels by radiochemical neutron activation analysis with liquid scintillation counting

Analytical Methods for Sulfur Determination in Glasses, Rocks, Minerals and Fluid Inclusions

“…Sulfur may be determined by measurement of 35 S (t 1/2 , 87 d) produced via neutron capture of 34 S (Bouten and Hoste 1962;Li and Filby 1983;Paul 2008), and by measurement of 32 P (t 1/2 , 14.28 d) formed via the 32 S(n, p) 32 P reaction (McCandless 1964;Souliotis 1964;Wayman 1964). Both nuclides are pure beta emitters, with maximum beta energies of 1.7 MeV for 32 P and 0.167 MeV for 35 S. Radiochemical separation of these nuclides from the sample matrix is necessary to avoid spectral interferences and to improve detection limits.…”

“…Accurate measurement of sulfur therefore requires measurement of and correction for the interfering element. For measurement of sulfur via 35 S, a Cl/S ratio of 0.003 results in a 10% correction (Paul 2008). Li and Filby (1983) measured sulfur mass fractions from 0.7% to 4% in fuel oils with Cl/S ratios < 0.003 with 1σ uncertainties of < 3%, but for biological materials with < 0.3% sulfur and Cl/S > 0.3, uncertainties up to 50% were reported.…”

“…Li and Filby (1983) measured sulfur mass fractions from 0.7% to 4% in fuel oils with Cl/S ratios < 0.003 with 1σ uncertainties of < 3%, but for biological materials with < 0.3% sulfur and Cl/S > 0.3, uncertainties up to 50% were reported. Paul (2008) measured 5 μg/g sulfur in a 1 g sample of ultra-high-purity iron by the 35 S method, with an irradiation time of 8 h. (Paul 2008) and an expanded uncertainty of about 10%, with a 30% correction for the chlorine (also measured by NAA). A detection limit of 0.1 μg was calculated for sulfur in a sample with 0.1 μg Cl.…”

“…A detection limit of 0.1 μg was calculated for sulfur in a sample with 0.1 μg Cl. A general discussion of uncertainties arising in RNAA procedures is given elsewhere (Paul et al 2003;Paul 2008).…”

Prompt gamma-ray activation analysis for certification of sulfur in fuel oil SRMs

“…Instrumental neutron activation (INAA), with counting of the 3102 keV gamma ray emitted by 37 S (produced by neutron capture on 36 S), has been used to measure sulfur 1–3 , however the low and variable isotopic abundance of 36 S limits both the detection limit and accuracy of the method. 4 Radiochemical neutron activation analysis (RNAA), with liquid scintillation counting of the 0.17 MeV beta from 35 S (produced by neutron capture on 34 S), has also been used to measure sulfur at mg/kg levels 5,6 , however the chemistry needed to separate and purify 35 S is intensive and the method suffers from a large interference from the 35 Cl(n,p) 35 S reaction. Furthermore, the need to heat seal liquids in quartz vials for in-core irradiations makes both INAA and RNAA labor intensive and potentially dangerous for analysis of volatile fuel oils.…”