I'm a exempt employee who does not take a lunch, can my employer make me work 8.5 hrs per day?

The short answer is yes.  Generally speaking, an employer can "make" you work 8.5 hours / day, unless there is a contract that dictates otherwise.  However, MN law requires employers to allow restroom and lunch breaks (depending on how long the employee's scheduled shifts are). The real issue may be whether you are truly an "exempt" worker. There are many common misconceptions about when a worker is "exempt." If you are not actually exempt, then you may have a right to be paid more for any extra hours you work. Because I do not know enough about your situation, this answer is not to be considered as legal advice, and it does not establish an attorney-client relationship. For legal advice regarding your specific situation, please consult your attorney.