ELECTRON-ENERGY LOSS ANALYSIS OF NEAR-TRACE-ELEMENT CONCENTRATIONS OF CALCIUM

The quantitation of near-trace-element concentrations of calcium (25 ppm atomic fraction) with electron energy loss spectroscopy (EELS) is demonstrated. The quantitative results obtained with EELS, in the biologically relevant range of 1 to 100 mmol/kg, are directly compared with simultaneously collected and previously validated energy-dispersive X-Ray spectroscopy (EPMA). The experimentally determined sensitivity of EELS for Ca detection is five-fold better than for EPMA, and the theoretically attainable sensitivity of EELS is ten-fold better than for EPMA. However, the attainment of this sensitivity with EELS is technically more difficult and limited by specimen thickness.