What acids interfere with detecting Cr?

Regarding sample preparation and dissolution, oxidizing acids such as concentrated HNO3 and aqua regia can passivate elemental Cr by oxidizing the surface and rendering it insoluble.  HCl is a better choice for dissolving elemental Cr.  HNO3 and aqua regia can be used to digest metal alloys containing Cr as well as other Cr compounds.  For questions regarding acid interference in detection of Cr please consult your ICP/AA instrument manufacturer.