Determination of Amoxicillin Stability in Chicken Meat by Liquid Chromatography-Tandem Mass Spectrometry

An amoxicillin stability study was performed under different pH (1, 3 and 5) and temperature (4 A degrees C, 22 A degrees C, 37 A degrees C and 55 A degrees C) conditions and for incurred samples stored at -20 A degrees C with the goals of better understanding amoxicillin degradation and characterising its main degradation products (amoxicilloic acid and amoxicillin diketopiperazine). The analytical methodology used consisted of a simple extraction using phosphate buffer (pH 8) with sodium chloride followed by a sample clean-up using OASISA (R) HLB cartridges and a liquid chromatography-tandem mass spectrometric analysis. Amoxicillin was found to be greatly unstable at temperatures above 22 A degrees C for all pH values studied, so it was recommended that biological samples should be frozen at temperatures below -70 A degrees C until analysis of the amoxicillin residues.