trigger the approval workflow for PO change order ONLY when the cost center is modified

Summary:

REQUIREMENT: trigger the approval workflow for PO change order ONLY when the cost center is modified

Content (please ensure you mask any confidential information):

Hello,

Do you know how we could trigger the approval workflow for PO change order ONLY when the cost center is modified? The requirement would be:

• if only cost center is modified in the PO charge account, trigger the workflow
• if any other change is performed, approve automatically

How we could control that?

It would be ideal to have a field 'cost center modified', but it is not available.

But do we have any workaround to achieve that?