This is my first forray into taking platinum further than cementing it out of solution. I've AR'ed a couple dozen automotive oxygen sensors to strip platinum. I concentrated it down, dropped a nice quantity of yellow platinum salt with ammonium chloride, and filtered it. Now I'm left with a still reddish colored platinum solution diluted with ammonium chloride. It tests strongly for PT with the stannous test but adding more ammonium chloride doesn't yield any more PT salt. I'd like advice on possibly concentrating this solution down to attempt another drop. I'm hesitant to just start heating it given (residual) nitric and ammonium are both involved at this point. At least not unless you guys give me the all clear. The stannous test makes me think there is still enough value there to not just toss it in the stock pot just yet.