I used to know, but have forgotten. I do know that it contains an organic heterocyclic compound, that is, more specifically it is a ring system with nitrogen and carbon. It may be a piperazine or piperadine compound or something like that. It is what gives it that strange peppery odor. There is also a lacquer and another solvent there.
That is all I remember for the coater that goes onto a finished B&W print.
I've used regular rattle-can spray lacquer on many of my prints for just the same reason and 15+ years they are still good with no deterioration.