![]() This works best when the deposit is particularly thick: It is the usual procedure of one gold bath vendor that I know to have their customers plate a copper or brass coupon (small disk or rectangular piece) with over 1000 µinch, just the gold, not the underplate. This is a very thin foil so be careful you don't lose any while rinsing.Ģ. What you have left (after careful rinsing) is the gold shell. Use nitric acid to dissolve away the part. This will work with copper alloys: Cut open the part so that the base metal is exposed. This procedure seems to work ok but I don't like the fact that I have to dissolve all that extra metal and complicate the matrix. The second procedure I've tried is to dissolve the entire part in aqua regia. The numbers I'm getting indicate to me that the precipitate is a problem (either it's a gold salt or it absorbs gold). My problem with this technique is that it seems to result in the formation of a suspended solid. The dilution of the stripper solution in the acid matrix is of course performed in a hood to contain any hydrogen cyanide liberated in the process. I then take the gold laden stripper solution and put it into a 20% HCl, 5% HNO3 matrix since I would prefer to deal with an acid matrix to ensure compatibility with the other samples run on the instrument. The first is to semi-selectively dissolve the gold from our product with cyanide stripper. I've played around with two sample prep techniques. I'm trying to determine the quantity of gold deposited on our product. Plating, anodizing, & finishing Q&As since 1989
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