Hi dear Bayu

You can use Flame atomic absorption spectroscopy (FAAS) with microwave digestion.

cheers

It is not an easy subject. In order to determine chromium with normal wet chemical techniques you have to bring your sample into solution. Maintaining the original ballans of Cr3 and Cr6 will be difficult, not to mention the influence of Cr as part of the alloy.

I think that dry techniques like Auger spectroscopy or XPS would be more successful. If you really want a "wet" approach try ion chromatography, an other option may be found in an electrochemical methode.

It is very difficult to use wet chemical method for determine Cr(III) and Cr(VI) in steel. Because, in any digestion method, Cr(III) can oxidized to Cr(VI). In X-ray spectroscopic technique, you can map Cr(III) and Cr(VI) species. Binding energy calculation also can apply for this, however, it long process. I suggest Auger or XPS is good technique for this and try with it. If you dont have such facility, here I attached paper, that may useful. It described wet chemical method. However, you have to check the validity of this method.

You can determine extractable amount of Cr(VI) by using a basic solution. Further you can determine the total amount of Cr by microwave assisted digestion using the appropriate acid mixture.