As variable energy monochromatic sources both synchrotron radiation mo
nochromatic light and proton induced X-ray emission were used to study
X-ray fluorecence of K, Ca, Ti light elements. The results indicate t
hat this method not only reduces the bremsstrahlung background but als
o eliminates the interference with some other elements by selecting ap
propriate exciting energy. Thus the analytic sensitivity of K, Ca, Ti
elements are considerably improved.