a storage - stable aqueous concentrate for the preparation of a disinfectant and a disinfectant obtainable from such a concentrate by dilution are disclosed . the concentrate comprises hydrogen peroxide , colloidal silver , a biopolymeric stabilizer such as gum arabic , and phosphoric acid . in order to improve long - term stability and to reduce initial decomposition of the hydrogen peroxide in the first few days after preparing the concentrate , the concentrate further comprises sodium nitrate or sodium sulfate . the concentrate is free of any synthetic organic complexing agents , thus rendering the concentrate suitable for food - and drinking water applications . also disclosed are methods of preparing and using the concentrate .