Combine 100 mL ice-cold acetone with 100 mL 25% hydrogen peroxide, make sure that the temperature is below 30°C. Cool down the solution to room temperature and add 20 mL of conc. hydrochloric acid. Cool the solution down to 0°C, filter and dry the crystals. Add a small amount of water to the storage container. The TATP sublimes at drying, dry it with sodium hydroxide desiccator bag.