phenol/chloroform extraction

[Yam Lung STUDENT]

I think the white interface is protein from tissues and usually I would
just take the aqueous phase without touching that interface because it
would contaminate your DNA sample.  Also, multiple extraction means
performing a series of phenol/chloroform extractions, id est, take the
aqueous phase of the first extraction to a new clean tube and add
phenol/chloroform and do a second extraction.  I hope this is the correct
answer.

Lung Yam
Department of Biology
The Johns Hopkins Unversity
Baltimore, Maryland
U S A