A validated stability-indicating high performance liquid chromatographic assay of amoxicillin

The purpose of this work is to develop a selective, simple, rapid and accurate liq. chromatog. method for the anal. of amoxicillin and its possible degrdn. products in bulk drug.  Amoxicillin and its degrdn. products were analyzed on Ultrasphere C18 column, using a mobile system contg. 4​% methanol in 0.01 M potassium dihydrogen phosphate soln., 2 mM triethylamine, and adjusted to pH 3.6 with 0.1 M phosphoric acid.  The samples were monitored at wavelength 242 nm.  Amoxicillin was forcedly degraded in powder and soln. forms under all possible stress conditions.  The forced degrdn. conditions were including the effect of daylight, heat, moisture, acid-​base hydrolysis, sonication, and oxidn.  Amoxicillin penicilloic acid (AMP) was the major degrdn. product formed under all stress conditions.  However, penicillamine (PM) and 6-​aminopenicillanic acid (6-​APA) were generated under severe stress conditions.  The detection and quantification limit of 6-​APA, PM and clavulanic acid were enhanced by the use of triethylamine as ion-​pair.  This method was also applicable for the detn. of both, amoxicillin and clavulanic acid in Augmentin parenteral.