Can we Stop a Buyer creating PO from a PR that they are the creator/Requstor

Summary:

Content (required):

Is there a way to stop a buyer who creates a requisition or is the requestor on it from then creating a Purchase Order from it, ie being able in essence to do the full end to end in Purchasing from Rec to Receipt?

Version (include the version you are using, if applicable):

21D

Code Snippet (add any code snippets that support your topic, if applicable):