Accurate determination of three halogen elements (Cl, Br, and I) in U.S. Geological Survey geochemical reference materials by radiochemical neutron activation analysis and an exhaustive comparison with literature data: a review

Since trace amounts of three halogens (chlorine, bromine, and iodine) in 17 U.S. Geological Survey (USGS) geochemical reference materials were recently determined using radiochemical neutron activation analysis (RNAA) by the authors, the RNAA data of the three halogens were exhaustively compared with corresponding literature data and some inconsistencies were found. Those inconsistencies can be explained by the loss of iodine in pretreatment of the solution that is subjected to inductively coupled plasma mass spectrometry (ICPMS), incomplete quantitative collection of chlorine in pyrohydrolysis preconcentration for ICPMS, and overestimation due to the interference in the ICP double focusing sector field MS (ICPSFMS) instrument. Using the relative standard deviation (RSD) that accompanies the mean value in each USGS material, homogeneity of halogens in the USGS materials has been discussed.