Colorimetric determination of Amoxicillin using 4-Aminoantipyrine and the effects of different parameters

The wide utilize of antibiotics has led to spreading of antibiotics resistance among bacterial populations and reducing the effectiveness of antibiotics. However, most of the administrated antibiotics enter the environmental matrixes through direct runoff and excretion of feces or urine as unchanged original drugs, active metabolites and/or degradation products. Amoxicillin is one of the most valuable and highly consumed antibiotics. Thus, amoxicillin removal from pharmaceutical wastes offers many economic and environmental benefits. Therefore, the aim of current study was to characterize an identification method for amoxicillin and to study the effects of different parameter such as order of addition, nature of the complex, temperature and effect of concentration and type of the base. A spectrophotometric, selective and sensitive method has been proposed for the determination of Amoxicillin. The method is based on the oxidation of potassium ferricyanide and coupling of the oxidized product with the reagent, 4- aminoantipyrine, to give intensely colored complex that absorbs light strongly in the spectral region of 509nm at room temperature. The results found that the order of addition, drug (Amoxicillin)- potassium ferricyanide –base-4- aminoantipyrine, gave highest absorbance and sensitivity, the best base was NaOH (0.1N) needful for developing the colored product and increase its stability. That complex, at 25°C, gave a preferable sensitivity and was selected for further use in this study. Under the proposed optimum conditions, Beer's law was conform in the concentration range of ( 5-100 mg L⁻¹). Good linearity (r²=0.9994). Calculation of standard error, limit of detection (LOD) (signal/noise = 3), accuracy and precision (RSD%) better than 1%. The utilized method seemed simple, rapid, reproducible and accurate. In addition, it is applicable for the assay of the drug under investigation in various dosage forms and the results are in very good concord with those obtained in previous studies. (paper)