AFAIK, no. Check your bags through, if at all possible. If you're traveling on two different airlines and the first will not through-check to the second, you may be SOL. I doubt the second airline would allow you to check in 8 hours before your flight, although you could always try it.

Be aware also that baggage claim at PHL is notoriously slow. Your 8 hour connection might be more like 7 by the time you get your bag.