Glass bead with minimized amount (11 mg) of sample for X-ray fluorescence determination of archaeological ceramics

摘要

By using very small amount – 11-mg – of sample powder, major oxides (Na_2O, MgO, Al_2O_3, SiO_2, P_2O_5, K_2O, CaO, TiO_2, MnO, and total Fe_2O_3) in ancient pottery (and igneous rocks) were determined with X-ray fluorescence spectrometry. This minimized amount of sample was used to prepare a fused glass bead with 300 times the weight of lithium tetraborate as an alkali flux. Calibration standards were obtained by compounding chemical reagents (Na_2CO_3, MgO, Al_2O_3, SiO_2, Na_4P_2O_7, K_2CO_3, CaCO_3, TiO_2, MnO_2, and Fe_2O_3) and the flux. Fewer 11mg of reagents as oxides were able to give reliable calibration curves with good linearity (correlation coefficient: r>0.995). Fewer 11mg of sample was able to give reliable analytical results with good precision (relative standard deviation: <3% for more than 10.0 mass% of analyte, <10% for 1.0–10.0 mass% of analyte, and <20% for 0.1–1.0 mass% of analyte). Lower limits of detection were roughly a sub-percentage of analyte in an unprepared sample (e.g. 0.3 mass% for Na2O, 0.5 mass% for MgO, 1.0 mass% for Al_2O_3, and 0.01 mass% for MnO). Composition of major oxides in artificial and natural aluminosilicate materials (including rock, stone, sand, sediment, and clay; and their products) should be fundamental information to be considered in detail. The present X-ray determination based on very small amount of sample might be made readily accessible for destructive analysis of precious samples for archaeology (and geochemistry).