Sequential Injection Analysis for the Simultaneous Determination of Clavulanic Acid and Amoxicillin in Pharmaceuticals Using Second-order Calibration

In this paper, we report on a method for quantifying clavulanic acid and amoxicillin simultaneously in pharmaceuticals using sequential injection analysis (SIA) with a diode-array spectrophotometric detector and multivariate curve resolution with alternating least squares (MCR-ALS). We optimized the experimental parameters so that the analytical sequence could distinguish the concentrations and spectrum profiles of the species of interest with optimum resolution quality. After establishing the optimum conditions, we quantified clavulanic acid and amoxicillin in four pharmaceuticals. In most cases our results were slightly higher than those in the prospectus of the pharmaceutical. The relative standard deviations were below 5% for amoxicillin and below 7% for clavulanic acid. These results are acceptable because, to prevent degradation due to bacteriostatic activity, the concentration of the main reactant is usually higher.