Abstract

A NEW SPECTROPHOTOMETRIC METHOD FOR DETERMINATION OF AMOXICILLIN USING BROMOCRESOL GREEN

Mrudul R. Keskar*, Ravin M. Jugade

ABSTRACT

Simple and rapid spectrophotometric method has been developed for the determination of amoxicillin in bulk and pharmaceutical formulations. The method is based on the formation of blue ion-pair complex between amoxicillin and bromocresol green in dimethylsulphoxide medium. The studies have been carried out with Spectronic 20D+ (Thermospectronic) visible spectrophotometer. The absorption maxima of the complex was found to be 630 nm. The composition of complex was determined by Job’s method was found to be 2:1 (Drug: Reagent). Different variables affecting the reaction were studied and parameters such as time, reagent concentration etc were optimised. The formed complex was quantified spectrophotometrically at absorption maxima. Concentration of bromocresol green was found to be optimum at 9.6μM. Under the optimum conditions calibration graph was found to be linear over the range of 1-13 μg/ml with detection limit 0.06μg/ml. Thermodynamic studies were carried out including stability constant (log K=4.97) and Gibb’s free energy change (ΔG = –2.8167 x 104 kJ/mol). Validation parameters such as Sandell’s sensitivilty, correlation coefficient, coefficient of determination, standard deviation and relative standard deviation were determined. Recovery studies were carried out. The method was successfully applied for the determination of amoxicillin in pharmaceutical formulations such as tablets, capsules and oral suspension. The proposed method is simple, direct, sensitive and do not require any extraction process. Thus, this method could be readily applicable for the quality control and routine analysis.

Keywords: Amoxicillin, bromocresol green, ion-pair complex, spectrophotometry.