Green Spectrophotometric Determination of Amoxicillin Anti-Biotic Drug in Pure Form and Pharmaceuticals Using Ninhydrin

Abstract

An inexpensive, accurate, and simple green spectrophotometric assay was developed and validated for the determination of the antibiotic drug, Amoxicillin (AMX), in pure drug and tablet using ninhydrin (NIH). The method relied on the condensation reaction between the drug and Ninhydrin reagent (NIH) in the present NaHCO₃, and then the colored product was measured at 420 nm. The absorbance measured was related to AMX concentration. Different experimental conditions of assay were studied, and optimized. Beer’s law for the method is obeyed over the concentration ranges 30-180 µg mL^-1. The molar absorptivity value was 1.76×10³ L mol^-1 cm¹. The limits detection (LOD) and quantification (LOQ) values were 0.9 and 2.73 mg mL^-1. The method was validated according to ICH guidelines for precision and accuracy, robustness and ruggedness, and selectivity. The intraday and inter-day relative standard deviation (%RSD) values for precisions were found to be in the range of 1.53–2.62%, whereas the respective relative error (%RE) values for accuracy were better than 2.25%. Robustness and ruggedness were tested, and the %RSD values were within the accepted limits in both instances. Also, placebo blank and synthetic mixture analysis was applied for method selectivity. The results showed that there is no interference resulting from co-formulated materials in the developed method. The assay was successfully applied for the determination of AMX in commercial tablets and capsules with reliable, satisfactory results, and indicated that the proposed method was as accurate and precise as the official methods. Hence, the proposed method can be applied in pharmaceutical laboratories of quality control.