USP method for testing ethanol

[Consumer Products Guy]

RB6banjo - We do ethanol assay frequently, pretty similar to what KM-USA does, injecting the water solutions. Our ethanol/ACN RSD is way better than what you obtained.

I haven't studied the ratio of ethanol to ACN v time though.

[rb6banjo]

I get that. The original post indicated that some reaction was happening causing the ACN to disappear. This is not an analysis that I do routinely. I was just trying to eliminate chemistry happening in the standard from what might be happening in the chromatograph because of the substantially water injection. This was an easy way not to do water injections yet demonstrate that the standard is reasonably stable over a weeks time.