And Steve, let me know if you want any more of it (if there is enough demand, I will make a bunch of the stuff). Keep in mind that I deal usually with things like what I sent you: pure metal complexes of known or stated purity. In this, hydrazine and its salts far exceed the others. It is clean, fast, and complete in its reduction.
For a mixed bag of PGMs, as Chris mentioned, it can be made selective depending on pH and temperature. The hotter the hydrazine solution is, the more indiscriminate it is. There are always other factors, namely solution concentration, and what the anions involved are. For Pt, Pd, and Rh, individually, I always make the values solution basic with either NaOH or preferably, ammonia. Then I dissolve up the hydrazine sulfate or dihydrochloride in hot water and add it to the beaker with the values. I do that slowly, because as the metals is reduced, the hydrazine is oxidized, and one of the products is nitrogen gas.
As for using pure ethanol for rhodium, I do not advocate its use at all. Only for Os and Ru is it of any use in my honest opinion. Starting from pure rhodium compounds and using EtOH as reducer, I always end up with rhodium black, which, unlike what Randy from Gunnison has said, is murder to filter, even on fine glass frit with a powerful vacuum. It's not something I'd recommend anyone to do unless they have patience and the equipment. Patience most here have, but I probably wouldn't be wrong if I said you lot aren't equipped like I am.
Hydrazine is a waste on gold. According to GSP/Chris, it can however be used to avoid the whole ''boil down to HAuCl4 syrup'' deNOx procedure. I've never actually used hydrazine sulfate to drop gold from aqua regia (bold because I would NEVER add hydrazine free base to any solution containing nitric acid!). In fact, this is quite tempting to do as it would save time. Again, all fine assuming your gold is pure in its solution. If it isn't that's when the more mild reducing agents like SO2, oxalic acid, ferrous sulfate, etc. come into play.
As for Shor patenting basic chemical knowledge, to hell with that!!! That pisses me off. I've done probably everything in that patent many times without ever even reading it til now. There's nothing novel about that at all! Typical example of a patent that should not be a patent.
Lou
