  The master equation of one-dimensional three-species reaction-diffusion
processes is mapped onto an imaginary-time Schr\"odinger equation. In many
cases the Hamiltonian obtained is that of an integrable quantum chain. Within
this approach we search for all $3$-state integrable quantum chains whose
spectra are known and which are related to diffusive-reactive systems.Two
integrable models are found to appear naturally in this context: the
$U_{q}\widehat{SU(2)}$-invariant model with external fields and the $3$-state
$U_q Su(P/M)$-invariant Perk-Schultz models with external fields. A nonlocal
similarity transformation which brings the Hamiltonian governing the chemical
processes to the known standard forms is described, leading in the case of
periodic boundary conditions to a generalization of the Dzialoshinsky-Moriya
interaction.
