HELP: RNA/DNA seperation

[Mr. G. Morley]

Hello one and all...
I was hoping someone could help me with a problem
a colleage of mine has...
Basically he is trying to construct a ribo probe
but is having difficulty removing all of the DNA
template that the riboprobe is made from..DNA'se
digestion removes most,but not all of the DNA and
he was wondering if:
a) There is a way of seperating the two out (ie: 
Sephadex columns)
b) Any methodology for extracting RNA from a formamide-agarose
gel.
Thanks in advance for any responses! If one works I will
post it to this group. Thanks again,
Gary Morley (gmorley at rpms.ac.uk)