A sliver of absorbent material impregnated with chemical indicators and dyes intended to be used to rapidly indicate, through colour change, the concentration of glutaraldehyde in a device disinfectant and/or sterilant solution after preparation to ensure disinfectant/sterilant properties. It is used to prevent diluting the disinfectant/sterilant to a concentration that is lower than the manufacturer's recommended minimum effective concentration (MEC). This is a single-use device.