Gold will dissolve in aqua regia, but tantalum only dissolves in hydrofluoric acid, which is not a very happy situation. Deal with the gold first, then if you must, do a HF treatment. In teflon vessels or what have you.

You can use a potassium carbonate flux to digest both elements, but it takes quite a bit of practice to become efficient and it is very laborious and tedious work. We've had success using mixed acid reagents (HCl/HNO3/HF) in high pressure bombs (Parr Teflon) but you have to make sure you ash the sample prior to digestion to destroy any organics present since that acid mix is rather unstable with organics present. You don't mention your sample matrix, so I am supposing that it is a solid.

HF can be an issue post-digestion for most analytical systems, and without the HF present tantalum isn't stable in solution. We use an all-plastic sample introduction system with ICP-OES for samples that contain HF.

Thanks Pavlov,

I have already tried dissolving gold with aqua regia and it works, but I am unable to dissolve Ta.. !

What about a mixture of both aqua regia and HF together.. Will it make any trouble for analyzing Ta and Au in ICP...? Can I put both in a alumina crucible for dissolving.?

Definitely NOT on the alumina crucible; it's soluble in HF.

Yes, HF causes you lots and lots of problems on ICP. Read the literature; there are several ways to get around the HF issue.

We use Teflon for HF digestions, since aqua regia and HF together make for a very powerful acid combination. Read my previous post.