Spectrophotometric Determination of Ampicillin Using Chromogenic Reagents (MBTH and PDAC) and their Application in Pharmaceutical Formulations

The present work highlights the spectrophotometric method development and validation for the assay of ampicillin, a broad-spectrum β-lactam antibiotic. Two methods have been proposed by employing popular chromogenic reagents viz 3-methyl 2-benzothiazolinone hydrazone (MBTH) and para dimethyl amino cinnamaldehyde (PDAC). Method A involves the coupling of ampicillin with MBTH in the presence of ferric chloride through the oxidative mechanism, resulting in the formation of green coloured solution with a maximum absorption peak at 620 nm. In method B, the condensation reaction of ampicillin with an acidic solution of PDAC gave a coloured reddish-brown complex, showing a maximum absorption peak at 514nm. Linear calibration curve for MBTH and PDAC has been obtained while obeying Beer’s law in the concentration range of 0.5 -1 and 5-15 μg/ml having a good correlation coefficient of 0.9985 and 0.9974 respectively. The sensitivity of the submitted methods was found to be more than the reported methods. Both methods were successfully applied to a pharmaceutical formulation for quantifying the ampicillin effectively. Therefore, the developed spectrophotometric methods can serve as a good analytical assay procedure for ampicillin to undergo quality control in pharmaceutical setups.