Internal treatments of gas cylinders for toxic gas mixture

The values of toxic components like $\ce{H2S}$, $\ce{NO}$, $\ce{SO2}$, etc. [in ppm level] get decreased after a while due to adsorption phenomenon. Manufacturers design some internal treatments in order to prevent adsorption to obtain a stable mixture.

1. Do you have detailed information about different kinds of these treatments or do you know where I could find them?
2. What are other solutions leading to resolve this problem?