Steam-formaldehyde sterilization process indicator inks

Abstract

Chemical indicator inks for steam-formaldehyde sterilization processes. The chemical indicator ink contains at least one primary organic dye selected from the group consisting of Congo red, Benzo purpurin B, Chicago sky blue 6B, Direct red 75, Evans blue, Naphthol blue black, Nitro red, and combinations thereof. The organic dye undergoes an irreversible color change when exposed to formaldehyde vapor in the presence of steam, but will not change color when exposed to other sterilization processes. The chemical indicator ink can further contain at least one secondary organic dye which does not undergo a color change when exposed to formaldehyde vapor in the presence of steam.

Dependencies are inferred from the claim text.