Derivatization reaction in the gas-liquid chromatographic analysis paracetamol

Abstract

Paracetamol molecule contains two functional groups, -OH and –NH, and is therefore able to participate in at least one type of derivatization reaction called acetylation. Derivatization products consist of mixture of monoacetyl (MAAP) and diacetyl (DAAP)-derivatives. With three-hours incubation at 200°C, there were more DAAP formed than MAAP. Although both derivatives could be detected in a gas-liquid chromatographic (GLC) system employing a Carbowax 20M column, only DAAP was determined in this study. The peak area ratio of DAAP/benzophenone (which was used as internal standard) related directly to the amount of paracetamol used for acetylation, and a correlation coefficient (r = 0.9954) was obtained over a wide range (200-1000 mg) of paracetamol assayed. Further experiments indicate a good percent recovery with this system whether paracetamol was in tablet, syrup or injectable formulations suggesting therefore that this GLC system can be used as a good sensitive, accurate reproducible method as that recommended in USP XXII for the measurement of this important compound.