The methods using microwave irradiation for rapid preparation of acetyl, trifluoroacetyl, pentafluoropyl, heptafluorobutyl and MSTFA derivatives of Morphine, AMP and MAMP were developed. Conventional techniques for the reaction mixture to be heated need 30 min at 60-70 degrees C to form derivatizations, but by microwave irradiation, only 2-3 min is needed. The mass spectral fragmentation patterns and gas chromatographic retention times of the derivatives obtained by both microwave irradiation and conventional heating are similar.