The fact that your SN is labelled as "≥ 99.0% Reagent Grade" is a strong indicator of quality. That grade refers to a high purity chemical typically used for laboratory procedures, which is what we want for CTB protocols. Bartovation test strips can confirm the presence of nitrite but not its purity percentage and they are most useful for ruling out fake or entirely inactive substances. To test, dissolve a very small amount (literally a pinch) in distilled water, dip the test strip, and observe the colour change against the chart. Do not expose your entire SN supply to air. Test only what's necessary. Once opened, reseal
immediately in your airtight container with silica packs if possible. I got some cheap packs online.
You're correct that SN should be dissolved fully in water before ingestion. 25g in 50ml of distilled water is the standard. However, it is not advisable to pre mix the solution hours or days in advance, even in an airtight container. SN degrades in water over time, especially when exposed to air, light, or moisture. Only dissolve the powder minutes before use. Your airtight containers are great for storing the powder itself, not for storing the solution long term.
You're right to treat anti nausea mints as a comfort aid, not a substitute for proper antiemetics. The taste of SN is extremely salty, so mints may help a little post ingestion if nausea arises, but they will not prevent vomiting on their own. Some people use candy after they drink to get over the icky taste. The primary antiemetics used in successful protocols is meto, taken about an hour before SN. If these are unavailable, mints are fine as a minor aid but should not be relied upon.
A fast for 12–15 hours is optimal and reduces vomiting risk considerably. You mentioned being on an antidepressant and an antipsychotic so adding painkillers like paracetamol or NSAIDs may not offer significant benefit in this context, and given the polypharmacy risk, it's reasonable to omit them unless you experience chronic physical pain that needs addressing.
Valium is a good choice for calming the survival instinct and reducing panic. 10–30mg is typical, taken in the 1–2 hours prior. Propranolol may help reduce heart rate and physical anxiety symptoms, but take care with the dosing, as both it and diazepam are CNS depressants and can interact with existing medications. If unsure, err on the lower end of dosing and monitor how you respond in advance if possible!!
Having a barf bag or bin nearby is very sensible. The first signs of vomiting occur usually like 15–30 minutes in if they happen at all. Having two additional 25g/50ml solutions ready is smart. Many people cannot consume more than two full solutions due to the taste and gastric discomfort. One backup glass is often sufficient, but two is fine if you are aware of your limits.
Good luck, and remember that backing out and seeking help comes with no shame.
I have similar questions so replying to give this a boost also how long will you do the water fast for before the ingestion of SN? you don't use water when you swallow pills beforehand?
I replied to your thread as you had some extra questions.
I recommend you both utilise the search function here. Also read the PPH. Almost everything you asked is in there.