Now that you've posted pics, andygold - something is definitely not right.
You said the Purigen was bought new and that it was brown from the beginning - i.e. before any use whatsoever.
Unused/new Seachem Purigen comes in a fine mesh bag, or loose Purigen beads in a 250 ml jar, and is white, not brown. It gets brown after fairly lengthy usage in a filter, but returns to it's original white color after re-charging.
The pic you showed appears to contain product in an impermeable plastic-type bag - (like a re-sealable zip-lock type bag) - the water would not seem to flow through that for the Purigen to work. That's why you said it was still dry after the bottom of the bag sat in water. Purigen comes in a fine mesh bag that allows water to flow through it.
So something seems amiss here - what kind of bag is that exactly ?
No Purigen I've ever seen or bought comes in a bag like that.
If I'm right about the type of bag, and my eyes are not deceiving me, that product you got is not Seachem Purigen.