Chulavatnatol S, Charles B G
Department of Pharmacy, University of Queensland, Brisbane, Australia.
J Chromatogr. 1993 May 19;615(1):91-6. doi: 10.1016/0378-4347(93)80294-e.
A simple, robust high-performance liquid chromatographic method is described for assaying amoxicillin in urine. Sample clean-up involved solid-phase, ion-pair extraction onto Sep-Pak C18 cartridges followed by elution with acetonitrile (3%, v/v) in pH 4.85 buffer. Separations were performed on an Ultrasphere C18 column with a mobile phase comprising acetonitrile (32.5 ml) and pH 7.1 phosphate buffer (0.01 M, 1000 ml). Peaks were detected at 229 nm. Recovery was greater than 94%. Plots of peak area against urinary amoxicillin concentration were linear (r > 0.999) from 5 to 500 mg/l. Between-day and within-day imprecision (coefficient of variation) ranged between 3.0 and 15.5%. Inaccuracy was 7.1%, or less.
