Development of a direct and validated method of amoxicillin in physiological fluids using micellar liquid chromatography

Abbreviations MLC micellar liquid chromatography FDA food and drug analysis 2 Abstract A simple and robust method was developed for the routine identification and quantification of amoxicillin by micellar liquid chromatography. Amoxicillin, a β-lactamase inhibitor, is one of the most commonly prescribed drugs in the treatment of urine and skin structure infections. In this work, amoxicillin was determined in urine samples without any pre-treatment step in a phenyl column using a micellar mobile phase of 0.10 M sodium dodecyl sulfate and 4% butanol at pH 3. A UV detection set at 210 nm was used. Amoxicillin is eluted at 5.1 min with no interference by the protein band or endogenous compounds. Linearities (r > 0.9998), intra-and inter-day precisions were determined (RSD (%) 0.4-2.7% and 0.3-5%, respectively in micellar media, and 0.14-2.6% and 0.13-6%, respectively in urine), and robustness was studied in the validation of the method. LOD and LOQ were 0.06 and 0.4 µg/mL in micellar media and 0.11 and 0.4 µg/mL in urine, respectively. Recoveries in the urine matrix were in the range of 95-110%. The validated method proved to be reliable and sensitive for the determination of amoxicillin in urine samples.