A precursor comprises a tungsten precursor and a carbon-containing material. The precursor comprises less than 0.02% by weight of the carbon-containing material based on a total weight of the precursor. A method for purifying a tungsten precursor may comprise at least one of the following steps: obtaining a source vessel containing a tungsten precursor and a carbon-containing material; separating the tungsten precursor from at least a first portion of the carbon-containing material; recovering a precursor in a collection vessel; or any combination thereof.