Abstract:

In this study, we introduce an in situ, non-destructive method of chemical element identification utilizing a portable X-ray fluorescence spectrometer (pXRF) to identify the dominant elements of heavy metals in two volumes of Buddhist scriptures from Tang Dynasty collected by Nanjing University Museum. By detecting the ratio of mercury to iron in the scripture marks, and studying the color, we authenticated that the light words on one volume referred to the "blood scripture" were scripted in a mixture of blood and cinnabar. To validate the selection of pXRF rather than the energy dispersive X-ray spectroscopy (EDX) as the chosen detection method, we first analyzed the mercury and iron contents of ancient red pigment cinnabar powder (containing mercury), iron trioxide powder (containing iron), 50 : 50 and 99 : 1 mixtures of the two, and dried animal blood in the laboratory. The results confirmed that pXRF performed well in differentiating the relative contents of mercury and iron, even the trace levels of iron present in the blood sample. Following this check, we used pXRF to detect the dominant elements in the scripture marks of both volumes of Buddhist scriptures at the University Museum. The results indicated that the dark words on one volume referred to the "cinnabar scripture" were written in cinnabar; the light words on the most marks of the blood scripture were written in a mixture of blood and cinnabar, while the dark words on the few marks of the blood scripture were repaired by cinnabar. This study serves as a good example of the interdisciplinary application of college chemistry, providing a reliable, in situ, non-destructive method for element identification in blood scriptures that can be considered cultural relics.

Key words: Blood Buddhist scripture, Chemical element identification, Portable X-ray fluorescence spectrometry (pXRF)