Is anyone using an ethanol proof floating type meter to measure isopropyl? How do you calibrate it? How do get the water out of your isopropyl? Reflux with lime? There’s a Reddit post saying add nacl and decant, does that do it? Or mol seives? 3A, 4A?
Also, is the 91% isopropyl they sell for$10/gallon at Walmart typically contaminated? Wondering if we can purify and use that for extraction, but haven’t taken the time to track down the purity certificates.
I dont think they can be recalibrated for use with another solvent, even if the solvent you choose is an alcohol they have different densities so using an ethanol meter will give you slightly fucked readings in isopropyl.
Would be easier just buying ethanol proofing mol sieve and using that to remove water whenever you think it’s necesssry.
I suspect your ethanol proof hydrometer will provide a decent estimate of the isopropanol content. Those two substances have specific gravity whose differences with that of water vary by only 1.5% (0.7893 and 0.786 g/cm^3, respectively, vs about 1.000 for water, at 20 C).
Isopropanol is slightly less dense, so in its pure form it will allow an ethanol proof hydrometer to sink deeper, until it reads about 102%.
The ethanol proof hydrometer I looked at conveniently had two extra graduations above 100%…