# How to check purity of mercury metal

Mercury is a very good solvent for many metals. We have mercury metal available, how do we check for its purity? Is there some kind of test available to verify its purity? And, more helpfully, which kind of metals are dissolved in it?

• It depends on what is in the mercury, what you want to analyze for ( Zn may be ok, but not Ag for example) and what chemical instruments or techniques that you have available. Most of all when working with a heavy metal like mercury you need a good plan to dispose of the waste.
– MaxW
Feb 18 '16 at 6:41
• The mercury I'd have would most probably be used earlier. I am looking to eliminate heavy metals like Cd, Pb, As etc .. so wanted to see if there would be any simple test available to see if they are present? I am afraid I wont have some high sophisticated equipment availabe. Feb 18 '16 at 6:59

In case your mercury didn't come with an assay of the supplier, or has been used before, you might want to remove oxidizable metals by repeatedly dripping the mercury though diluted nitric acid and distilled water.

Subsequent distillation of mercury is certainly possible (at 25 mm Hg or lower), and has been reported by E. H. Riesenfeld and W. Haase in Ber. Dtsch. Chem. Ges., 1925, 58, 2828-2834 ( DOI).

In their article Über die Destillation von gold-haltigem Quecksilber ( = On the distillation of gold-containing mercury) the authors examined the distillation of gold-saturated mercury and stated that after two distillations, the gold content in the purified mercury was lower than 1.5 ng $\ce{Au}$ in 1 g $\ce{Hg}$.

UPDATE

In Joel H. Hildebrand, PURIFICATION OF MERCURY, J. Am. Chem. Soc., 1909, 31, 933-935, (DOI), the author seems to discuss further different methods,

THE PURIFICATION OF MERCURY BY AN ELECTROLYTIC METHOD Science, 1933, 78(2027), 414-415, (DOI) might be woth a look too.

However, please notice that these are rather old references. Please make sure, that the methods proposed are still in agreement with currents standards of lab safety and waste management!

• But wouldn't treating mercury with dilute nitric acid also react with mercury? Would that be a substantial amount? moreover which kind of metals should be expected from used mercury? and any guides for testing for their presence. I would prefer simple tests as having sophisticated laboratory scale equipment wont be available. Feb 18 '16 at 6:57
• @Muzammil The reaction of mercury with cold diluted nitric acid is much slower than with dissolved traces of less noble metals. So, the amount of loss is not significant. I already assumed that sophisticated analytics might not be available. Therefore I suggested simple purification techniques, rather than expensive analytical instruments. I'm afraid that there might not be a simple bench thest for trace analytics. Metal traces detected in the aqueous solutions might also come from the nitric acid itself. Feb 18 '16 at 7:09
• That explains a lot. Would this treatment remove Cd, As, Sb & Pb impurities ? If you have any documents or links to sophisticated techniques or purification methods, can you please share ? wouldn't hurt to take a look. Feb 18 '16 at 7:25