Biological standards for energy dispersive x-ray analysis

Biological standards containing known concentrations of crystalline silica were prepared for x-ray energy spectrometry (XES) using homogenized tissue and gelatin. Sections of 7 micrometer thickness were cut, air dried, carbon coated, and analyzed by XES. All sections containing crystalline silica generated x-ray counts on a linear relationship with increasing concentrations of silica in the standards. However, tissue sections containing identical concentrations of silica generated x-ray counts approximately 50 percent lower than gelatin sections. Gelatin sections showed considerable shrinkage during drying which may have influenced x-ray generation. The combined effects of elements present in the biological system and high density of tissues also may have contributed to the lower XES counts. These results stress the importance of using standards identical to specimens undergoing XES analysis.