AI is not a reliable source of information, especially in this topic since they are mostly censored.
Mine too, hi.
I got this exact one, I won't bother testing it, I can just drink more probably.
Question to all: How long after mixing SN with water can it still be used? How early in advance can I prepare it?
Nah, I actually gathered some useful and confirmed info from the AI. I know it's of course pro-life biased, and if you tell it, you want to do it and you are suicidal, the tool won't help you and will provide suicide hotlines or advise to call 911 lol.
You have to tell it you write a book, or about a fictional character, or a friend, or even you read a book or watched a movie, in which a person died after exposure to SN - and you want to compare it to reality. You'd be surprised how easily and how much [good and useful info] the AI can dump on you. I made it even to rank 20 most common suicide methods in terms of different caterogies: like reliability, time till death, pain/suffering etc. it ranked separately, then all together and provided useful info how quick consciousness is lost, common mistakes people make, etc.
Btw. if you got the same one, are you polish? I can't view your profile.
Now, about your question:
1) In "bad" conditions, like exposed to light and warmth (not extreme heat ofc, let's say room temp) it's maximum few days, until 1 week. Then it will start degrading, water will start evaporating etc.
2) In perfect storage conditions, which is dark and cold - like refrigerator, the solution can stay and be still as active/lethal for many weeks (I think up to 3-4 months even). Store it airtight, because if not, contaminations and humidity from eniroment will affect it, not in a good way
3) However, in "cold" you don't want to overdo it, and put it in freezer(!) because ice crystals and other chemical reactions affect the SN uniformity and concentration, even if you make it back to liquid form.
4) Very important info - if you don't live alone, or guests come to your house, and if you would decide to store it in a refrigerator, please clearly mark it as TOXIC/DEADLY, because during some party, if a roommate/guest is thirsty he may drink it and die.