(a) In a contract for professional services, public works or nonprofessional services, where the contract includes items that are a part of a central purchasing contract, those items shall not be subject to the purchasing requirements of this title.
(b) If a service or a materiel is a component part of a specific project that is part of another contract, then the requirements of this subchapter shall not apply.
(c) This section is not intended to allow agencies to avoid the use of central purchasing contracts by contracting with a vendor under the auspices of procuring a good or service when the sole or partial purpose of such a contract is to procure from that vendor another good or service that is on a central purchasing contract.