Flow-through solid phase UV spectrophotometric determination of amoxycillin

The determination of amoxycillin using a flow-injection method with spectro photometric detection is described. The method is based on the measurement of the intrinsic absorbance of amoxycillin fixed on Sephadex QAE A-25 resin . The determination of amoxycillin, using optimized variables, was carried out for three different sample volumes (300, 600 and 1200 mu l), giving lin ear calibration graphs over the ranges 2-50, 1-25 and 0.5-15 mu g ml(-1), r espectively. The relative standard deviations were less than or equal to 1% . The proposed method allows a very sensitive, rapid, and simple determinat ion of amoxycillin in the presence of other penicillins, antibiotics, addit ives and excipients, without performing a prior separation or derivatizatio n. A noticeable increase in sensitivity and lower detection limits can be e asily achieved by increasing the sample volume injected. The method was suc cessfully applied for the determination of amoxycillin in pharmaceutical fo rmulations.