Recent changes to biblatex (in v1.6) mean that the biblatex-chem bundle is currently broken. I’ve not released a quick-fix as there are some long-standing issues to address in biblatex-chem. When I initially wrote the code, I started from scratch and defined only what I wanted. That works, but means that any changes in biblatex are not automatically picked up. From biblatex-ieee, I took the alternative approach and worked from the standard biblatex styles to what was needed. That’s a better long-term approach, so it’s the one I’m now bringing to biblatex-chem. It will take a little while, so user might want to keep an eye on the development code.
Another day, another biblatex-chem update. I’ve added the ability to only use the first page of a range to all of the styles. Some journals require this, and I’d prefer to keep the total number of styles down with appropriate options. This is such a trivial variation it seems to be the best way to me.
I’ve just spotted a bug in biblatex-chem, and a fix is on the way to CTAN. It looks like changes in the biblatex core have made the comma after journal titles when using the chem-rsc style disappear. This was working earlier: I’ve retested an old version and it is not due to anything I’ve done.
On another matter, I’ve been asked to look at turning page ranges into single pages in biblatex-chem. I need to add the appropriate functions to biblatex, so there may be a delay (I have lots on at the moment). It is definitely on my list to do. Why do this? Well, some journals insist on first-page only, but in a database both pages will be present. So the code needs to handle things. There should be another update once I sort this: a few days.