PR Approval rules based on Preparer's Department

Summary: We are trying to build a requisition approval rule where we want to utilize the preparer's department (2nd segment of the charge account attached with user). I am unable to get the preparer's department field on the UI. Also, when I am trying to create the rule, the 'values' for 2nd segment is not coming in the list of values for department.

Can anyone suggest, what could the problem be? How can we build the rules based on Requester's charge account's 2nd segment?

Content (please ensure you mask any confidential information):Yes

Version (include the version you are using, if applicable):25C