Ca/P = (Ca atomic %)/ (P atomic %) = 44.22/22.65 = 1.95. Somewhat high for proper HA (1.67). For better results use a piece of stoichiometric synthetic HA as a standard and acquire data from multiple spots.
Thank you Sir Vladimir Dusevich , but can I ask why would I need to use a a piece of stoichiometric synthetic HA as a standard and acquire data from multiple spots?
Utilizing standards can significantly improve quality of EDS analysis, especially of samples containing light elements, such as O. Multiple spots are needed to get an average result (applying statistics) in case of uneven distribution of elements and to get rid of error caused by small topografical irregularities of specimen surface.