Shaykh Hasanyn Kassamali is the founder and religious director of the Academy for Learning Islam. He has a B.A. in Sociology from the University of Alberta and a Masters in Islamic Studies from the University of British Columbia. He has studied hawza program at Islamic seminaries in the Middle East.
An animal product is impure (najis) if both of the following are present:
- At the time of slaughtering the animal, its blood comes out with gush, and
- Such animal (as mentioned above) is not slaughtered according to method prescribed by Islam, nor is there a probability that it may have been slaughtered thus.
Now if these conditions apply to Collagen then it is najis, otherwise it is pure (paak).
Reference: See Tawdheehul Masaa'il of both Ayatullah al-Khu'i (may God have mercy on his ruh) and and al-Seestani in the chapter of Najasat under the discussion of "Dead Body".