How to detect content change in meta og:description?

[dotcomUNDERGROUND]

How do I detect changes in meta og:description?
The source code is like:
<meta property="og:description" content="CONTENT CHANGE" />

[Nionor]

You probably solved it by now but maybe it can help someone else.
From your example something like this should work.

xpath1://meta[starts-with(@property,'og:description')]/@content

[dotcomUNDERGROUND]

Thank you!