Glow discharge mass spectrometry (GDMS) has been used to provide trace elemental analysis of tungsten filaments used in ion implantation technology. Results indicated very large potassium signals on all of the tungsten samples with levels from 310 to 710 ppm (parts per million). Aluminum levels reached as high as 38 ppm. Cr, Fe, and Ni were detected with levels ranging from 1.1 ppb (parts per billion) to 14 ppm. Most filaments had radioactive levels of Th not exceeding 1.1 ppm except for one supplier which had a measured level of 26 ppm. Sodium levels varied from 0.24 ppm to 17 ppm. GDMS results from used source filaments indicated that filament lifetimes can be drastically extended by providing tungsten liners in the plasma arc chamber.