for what potassium perchlorate is used in mobile phase?

[bkbc]

Dear all,
Could anyone help with this topic? It appears in a drug analysis method as a reagent of mobile phase A.
B...

[Andy Alpert]

I would be interested in more details about this method. Sodium perchlorate is extremely soluble in both water and solutions containing high levels of organic solvents. Potassium perchlorate has low solubility in either. It's one of the biggest disparities in properties I've seen in a sodium vs. a potassium salt.

[bkbc]

I would be interested in more details about this method. Sodium perchlorate is extremely soluble in both water and solutions containing high levels of organic solvents. Potassium perchlorate has low solubility in either. It's one of the biggest disparities in properties I've seen in a sodium vs. a potassium salt.

Andy,
The Phase A is 1L water with 11.08g potassium perchlorate and 0.05%TFA.
The phase B is 1L ACN with 5.54g potassium perchlorate and 0.05%TFA.
could you give some comment?
B

[Andy Alpert]

Both TFA and perchlorate salts are chaotropes. This means that they keep something in solution that ordinarily would precipitate, or else they promote retention of something in reversed-phase chromatography (chaotropes promote retention in that mode). Judging from the gradient you describe, it's the latter. However, I'm still skeptical about the solubility of potassium perchlorate, especially in mobile phase B. It's also still not clear why the sodium salt isn't being used instead. What is the application?

[bkbc]

Both TFA and perchlorate salts are chaotropes. This means that they keep something in solution that ordinarily would precipitate, or else they promote retention of something in reversed-phase chromatography (chaotropes promote retention in that mode). Judging from the gradient you describe, it's the latter. However, I'm still skeptical about the solubility of potassium perchlorate, especially in mobile phase B. It's also still not clear why the sodium salt isn't being used instead. What is the application?

Andy,
This method is for assay of a formula drug and degradation compouds.
B

[Andy Alpert]

It still makes no sense to use potassium perchlorate instead of sodium perchlorate. However, if that method produced a successful analysis that you must now reproduce, then I'm not going to argue.

[bkbc]

It still makes no sense to use potassium perchlorate instead of sodium perchlorate. However, if that method produced a successful analysis that you must now reproduce, then I'm not going to argue.

Dear Andy,
I am about to run this method first time. Obviousely I am not sure if it will be successul for the whole run.
Pls follow this topic if you still keep interested in my question.
Many thanks.
B

[sepscientologist]

Interesting that sodium carbonate is nearly twice as soluble in water than potassium carbonate.