The administrator, with the consent of the Governor, shall employ all necessary assistants, engineers, janitors, custodians, and caretakers, fix their compensation, and terminate such employment from time to time as necessary for the efficient and economical discharge of his or her duties. The administrator shall purchase, through the materiel division of the Department of Administrative Services, such supplies, material, and equipment as may be necessary for the proper maintenance of the state laboratory and laboratory grounds, the Governor’s Mansion and grounds, and all other buildings and lands owned or leased by the State of Nebraska except as exempted under subsections (5) and (6) of section 81-1108.15 or as provided in the Nebraska State Capitol Preservation and Restoration Act. The total expenditures for such purposes shall not exceed the appropriations made for such purposes.