A method for preparing a concentrated solution containing water, citrate ionsand silver ions, including providingan amount of trisilver citrate, providing an amount of citric acid, whereinthe amount of the citric acid is at least 19 times theamount of the trisilver citrate by weight, and mixing the trisilver citrateand the citric acid in an amount of water to produce theconcentrated solution, wherein the amount of water is selected so that theconcentrated solution has a citrate ion concentrationwhich is at least 300 grams per liter. A concentrated solution containingwater, citrate ions and silver ions, wherein the concentratedsolution has a silver ion concentration which is at least 10 grams per liter.A diluted solution prepared by adding water to aconcentrated solution containing water, citrate ions and silver ions.
