[TheUnassuming]

Our labs SDS system went down so we set up a sodium/benzophenone still to dry THF and it worked well for one round.  It got low so we added more THF (which changed it to a yellow/orange color) and a bit more sodium/benzophenone before refluxing for a few hours to re-establish the desired deep purple color.  The problem we are encountering is a slight purple/blue color in the distillate.
Has anyone else ever encountered this/have suggestions?  If worse comes to worse it can always be torn down and a new one set up but I'd rather avoid it

[ziqquratu]

We used to have this problem all the time. The conclusion was that it arose when there was too much benzophenone in the still (i.e. the concentration was too high).

The only solution we came up with was to remake the still, unfortunately. The key is to only add a tiny amount of benzophenone when you make the still up - I think we used to use perhaps 1 tablespoon of benzophenone for 4 litres of THF (and that was probably too much, too!). With that little amount, you could refill the still perhaps 5 times before it'd be dead (with sufficient sodium, of course!).

Also, you should always reflux the THF for some time before adding the benzophenone, to ensure it is dry and oxygen free - our THF was a bit crappy (even from a fresh bottle), so we always refluxed the still for a minimum of 12 hours (or better two 12 hour periods over 2 days - never leave it to reflux unattended!) before adding the benzophenone.

[TheUnassuming]

Agreed, I rigged our GCMS back up and running and it confirms the contamination.  I found that by dropping the temp down to the point where it was distilling verrry slowly, the blue color doesn't seem to be coming over and the GC looks much better. 
Once this batch is dead I'll quench and set up a new one with much less benzophenone.
Thank you for your *delete me*