The licensed tester shall retain an unmodified sample of any milk, cream, or fluid derivative of milk or cream which is tested by him for a period of time which is specified in regulations adopted by the director after tests of milk or cream have been made. The purchaser, receiver, or seller of milk or cream or fluid derivative of milk or cream shall provide a suitable place where the samples which are retained by the tester may be kept. Such place shall be acceptable to the department.