Section 19. Subject to the provisions of section one hundred and three of chapter forty-one, to the extent permitted by charter or local by-law in a city or town, or by written rules of the committee, commission or executive appointing the chief procurement officer in a district or county, a chief procurement officer may delegate his powers and duties in accordance with this section to one or more employees of the governmental body. A delegation shall be in writing, be signed by the chief procurement officer, and state the activity or function authorized and the duration of the delegation. A delegation may be in specific or general terms, may be limited to a particular procurement or class of procurements, and may be conditioned upon compliance with specified procedures. A delegation may be revoked or amended whenever the chief procurement officer determines that revocation or amendment is in the best interests of the governmental body. A delegation of powers or duties by a chief procurement officer and any revocation or amendment thereof shall not take effect until a copy of the same has been filed with the office of the inspector general.