XeTeX ⇒ Asana Math | No roman upright Text

[tafi]

Hi there,

I'm having trouble getting te isotope package to work correctly with xelatex. The expected behaviour is that the element symbol and superscript mass number be typeset in normal roman font (upright) and I've got this to run fine in latex or pdflatex in the past.

However, xelatex seems intent on typesetting the element symbol in italics (maybe as maths or maybe as emphasised text).

I've traced the problem back to the Asana Math font. Isotope uses a math environment to typeset the atomic mass number as a supercript to an element symbol in upright roman text. But the Asana Math I have doesn't appear to be able to do this and so just typsets the element symbol as normal maths.

Is there a problem with my particular Asana Math (perhaps I don't have it installed properly). Or is this a problem with Asana Math generally?
If so is there an alternative palatino-esque mathematics font?

Using CM for maths (and hence isotopes) and palatino for the rest will look bad.

Many thanks

[tafi]

The problem seems to stem from the age of the isotope package. I am now using mhchem.