SPECTROPHOTOMETRIC DETERMINATION OF AMOXICILLIN IN PHARMACEUTICAL FORMULATIONS USING NORMAL AND REVERSE FLOW INJECTION ANALYSIS SYSTEMS: A COMPARISON STUDY

. The combination of flow injection technique and spectrophotometric detection can be employed for the rapid and low-cost methods for antibiotic assay. In this work, two flow injection analysis (FIA) systems, normal and reverse (nFIA and rFIA), combined with UV-Vis spectrophotometric technique were used for amoxicillin determination in its pure and pharmaceutical preparations. A colorimetric coupling reaction between amoxicillin and diazotized p-toluidine produced a bright yellow azo dye and quantified at a maximum wavelength of 426 nm. For nFIA and rFIA procedures, the amoxicillin calibration graphs had an RSD of less than 2% and were linear in the ranges of 5-200 and 1-140 mu g/mL, respectively. The limits of detection and quantification were 1.41 and 4.71 mu g/mL of amoxicillin for nFIA and 0.39 and 1.31 mu g/mL for rFIA, respectively. The physical and chemical factors that could influence color sensitivity were investigated. Various commercial formulations containing different amounts of amoxicillin were successfully tested using the developed approaches, which demonstrated to be easy, rapid, reproducible, and interference-free.