Hi Peggy.
That is a very specialized question. I am not an expert in white
dwarfs, but as your question has been up here for a few days I would
guess nobody else on our panel is either, so I will say what I can.
I did a quick search of the astrophysical literature (using
http://adsabs.harvard.edu/). It seems that there is hydrogen in white
dwarfs, although not much. There seem to be various people modeling the
details of how much hydrogen there should be and where. There are also
references to the H-alpha line. I don't have time to do more research
than that.
Cheers,
Terry