I very much want to know this, too. I'd like to have a stash on me wherever I go, just in case I need to use it immediately, before ctb. I'd read on here that it has to be refrigerated after coming into a solution. Something about the sn reacting in the water and making it less stable than in its powder form.
LLMs suggest:
Relatively stable in solid form, but when dissolved in water, its stability can be affected by several factors: temperature, light, oxygen exposure, ph, water or other contaminants, type of container.
Starting with a 99% powder mixed with water, it may remain above 95% concentration for a period of days to weeks under ideal storage conditions (cool, dark, and stable pH). The exact duration will depend on factors such as temperature, light exposure, and the presence of contaminants.
In less ideal conditions, the concentration could drop below 95% more quickly, potentially within hours to a few days. However, under optimal conditions, it is reasonable to expect that the solution could stay above 95% for at least several days.
If refrigerated, which slows down decomposition and other reactions, you might expect the solution to remain above 95% for weeks to potentially months, depending on the specific conditions (such as the purity of the water used, the container's exposure to light, and any contaminants). However, it's still advisable to monitor the solution and use it within a reasonable timeframe to ensure its effectiveness.