The pellets are apparently synthetic zeolite which is absorbent and traps odors. Which is kind of the opposite of what the pellets are designed to do, let the urine pass through. So I wonder about the absorbent part. They are also coated w/ a wax. I do know that zeolite is in other clumping litters.
I have wondered about what is in the pad however. Just put a piece of plastic over the pad, all you need is a drop to test for ketones and the rest can go off into the pad. You can tell where they usually go and just put the plastic there.
Also I hated the thought of putting all those pellets in the landfill, never to break down. I wash them out in a plastic sieve then soak overnight in a a 10% bleach solution, rinse and dry in the sun. No odor, I tried vinegar but you could still smell the urine.
I may do some testing, w/ weight and to see if they are ceramic. I taking a glaze formulation class and we are testing various materials. I wonder how the hold up to firing?