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

By using very small amount - 11-mg - of sample powder, major oxides (Na₂O, MgO, Al₂O₃, SiO₂, P₂O₅, K₂O, CaO, TiO₂, MnO, and total Fe₂O₃) 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 (Na₂CO₃, MgO, Al₂O₃, SiO₂, Na₄P₂O₇, K₂CO₃, CaCO₃, TiO₂, MnO₂, and Fe₂O₃) 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 10.0mass% of analyte, <10% for 1.0-10.0mass% of analyte, and <20% for 0.1-1.0mass% of analyte). Lower limits of detection were roughly a sub-percentage of analyte in an unprepared sample (e.g. 0.3mass% for Na₂O, 0.5mass% for MgO, 1.0mass% for Al₂O₃, and 0.01mass% 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).