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- Posts: 35
- Joined: Sun Apr 08, 2018 3:17 am
I recently posted about hexaflurophosphoric acid being used as an ion pairing agent. This was a misunderstanding on my part and recently discovered that it can be used as a chaotropic agent. I’m fairly new to the methodology but I prepared about a 25mM solution of hpf6 (about 5ml of 60% hpf6 in water). Adjusting the ph to about 4 with ammonium hydroxide. I got really great peak shape and separation but then all of a sudden the peak shape started deteriorating and went to hell. After previously posting this people said that a byproduct of Hpf6 is hydrofluoric acid which deteriorated the silica support. I spoke to someone recently and they said to use the salt form sodium hexaflorophosphate.
Isn’t this just going to do the same thing? I originally added hpf6 then adjusted with ammonium hydroxide but that’s forming s salt in solution.
I’ve also heard of sodium perchlorate being used for something similar. Is this just as effective of a chaotropic agent as pf6? Better? Worse? Since it’s perchlorate will it be a little better for my column? I was thinking of tryin 25mM is sodium perchlorate ph 4.
I’m trying to separate an n-oxide of a tertiary amine and have been having a hell of a time with it. I have a vendor method that uses acetic acid ph 4 but they have to go almost 100% aqueous and the main peak tails significantly