How do you remove residual Lawesson's reagent after thionation?

I am currently synthesizing a peptidomimetic bioisostere that replaces an oxygen with a sulfur. I use lawesson's reagent to achieve this, and althought the reaction works and despite running it through a column ( 80 mL silica, 10:1 DCM:MeOH) There is still a lot of residual lawesson's reagent left over. Does anyone have experience with this reagent and removing it? Any suggestions are appreciated


