Loose-powder technique for X-ray fluorescence analysis of ancient pottery using a small (100mg) powdered sample

A molded-loose-powder technique using a small powdered sample (100mg) was developed for the X-ray fluorescence analysis of 22 components (Na₂O, MgO, Al₂O₃, SiO₂, P₂O₅, K₂O, CaO, TiO₂, MnO, Fe₂O₃, V, Cr, Ni, Cu, Zn, Rb, Sr, Y, Zr, Nb, Ba, and Pb) in ancient pottery. This loose powder specimen was prepared by pressing the small powdered sample into a sample holder, formed from a stainless steel disk (48-mm diameter×0.8-mm height) with a hole (11-mm diameter), by hand. Calibration standards were prepared by homogenizing chemical reagents containing these 22 analytes using the concentration ranges of 166 ancient potteries and three clay materials from Japan. The calibration curves of these benchmark mixtures exhibited a good linearity (correlation coefficient, r=0.990-1.000), accuracy, and reproducibility compared with those of other synthesized specimens and three reference standards. The lower limits of detection were less than tens of mgkg^-1 (e.g., 94mgkg^-1 for Na₂O, 11mgkg^-1 for P₂O₅, 1.1mgkg^-1 for Rb, and 0.9mgkg^-1 for Y). Using the present method, we determined 22 components in two prehistoric potteries from Japan. The advantage of this method is that only a small amount of sample is required, which can be prepared easily and rapidly and reused for other analyses.