Redetermination of Mass Fractions of Three Halogens (Cl, Br, I) for Seventeen USGS Geochemical Reference Materials

The mass fractions of Cl, Br and I were obtained by radiochemical neutron activation analysis (RNAA) of seventeen USGS geochemical reference materials (RMs), for which we had published halogen contents in GGR (Sekimoto and Ebihara 2017). Except for three RMs, 100 mg to > 300 mg of each powder material was used for a single analysis. After 10 min of neutron irradiation, a rapid radiochemical purification procedure was performed. Chemical yields were determined by the reactivation method. Each RM was analysed multiple times and consistent values were obtained for each element. Of the seventeen RMs, CLB-1, DGPM-1 and QLO-1a were also analysed by INAA. The INAA and RNAA results for CLB-1 and DGPM-1agree within 4%, implying that RNAA values obtained in this study are reliable. Compared with the 2017 data, the Cl and Br values obtained in this study were consistent, but the I values were 1/4 to 1/8 lower for all samples. It is concluded that the quantitative values of Cl and Br published in GGR in 2017 are reliable, while the I values are incorrect. Therefore, it is recommended that the I contents in the USGS RMs determined in this study be substituted in place of previous values.