Optimization of an extraction procedure for the accurate determination of total tin in eighteen Geological Survey of Japan rock reference materials
A fusion-extraction procedure for the determination of total tin in rocks and sediments by graphite furnace atomic absorption spectrometry (GFAAS) was reexamined and modified to obtain the optimum accuracy and precision. Several variations based on increases in the sample weight or extraction ratio were compared based on the determination of tin in 18 Geological Survey of Japan (GSJ) reference materials. The most accurate and precise procedure was found to be an 8:1 extraction of a 0.5 g rock sample fused with lithium metaborate and dissolved in 7.5% hydrochloric acid, using a 4% solution of trioctylphosphine oxide in methyl isobutyl ketone (TOPO-MIBK). Rocks containing <I ug/g total tin require a 0.5 g sample size for the utmost accuracy. Utilizing these modifications, tin concentrations were found to be within 0.1 ug/g for all of the GSJ reference standards with the exception of the rhyolites. Values are reported for the total tin content of three new GSJ reference materials, namely, JLk-1, JLs-1, and JDo-1.