The tungsten ore and molybdenum ore are refractory and usually dissolved by alkali fusion method.However,a lot of sodium ions in the flux would be introduced into sample solution and lead to high salinity with the pretreatment by alkali fusion.The high salinity could cause matrix interference and cone-hole blocking,which is disadvantageous to determination of trace rare earth elements by inductively coupled plasma mass spectrometry(ICP-MS).In order to solve this problem,the sample was fused with NaOH and Na...