[sofia57]

Dear all friends:

Need help~~~~

I am doing ICP(inductively coupled plasma) experiment, my sample there are 2 kinds of silver wire,
1.AgNi
2.AgSnO + InO.

Both 2 kinds wire are heated with Nitrate Acid(HNO3, concentration 70%) and then dissolved into together.
After mix with HNO3 and dissolved, produce little precipitate(solid).

This is the problem here. I do not want to see any precipitate.

follows I tried and fail
1.AgNi + HNO3 will produce precipitation.
2.AgSnO + InO + HNO3 after them dissolved, have little white precipitation more than 1.

Any one support good idea, let them dissolved completely and in liquid status with no precipitate?
DO I have any work to prepare?


The best regards by Emily
thanks for read!

[Arkcon]

Indium may well resist nitric acids, other rare impurities may as well.  Or you're seeing something refractory to this procedure, like glass or silica, or plastic.

Try to do this systematically.  First try aqua regia -- adding a little HCl to the solutions containing excess nitric.  See if it helps, and be alert, it may make cause a worse precipitate.  Don't do it backwards, HCl before nitric may work too, but may also form a resistant precipitate.

Do evaluate all your solutions via ICP.  Maybe you can prove conclusively that the precipitate isn't significantly affecting your accuracy.

[sofia57]

Do you mean aqua regia(3 HCl : 1~1.5 Nitric) right?

//Don't do it backwards, HCl before nitric may work too//
what do you mean this?

[Arkcon]

You may certainly try to dissolve the solid samples in carefully prepared aqua regia, and see if it dissolves the resistant material. Then see if it works in the ICP.

You can also do what I describe: add some HCl to the excess nitric solution.  Some of the complexes that make up aqua regia will form, and may help this tiny bit of resistant material dissolve.  Its sort of a short cut, since this is a tiny amount of resistant material.

Silver, lead and mercury form insoluble chlorides with HCl, which may shield the mass from the nitric.  On the other hand, ferrous metals passivate in nitric, shielding them from HCl and aqua regia.  So my little shortcut trick can backfire.