SPECTROPHOTOMETRIC DETERMINATION OF MEROPENEM IN BULK AND INJECTION FORMULATIONS BY 1, 2 NAPHTHO QUINONE 4-SULPHONIC ACID (NQS) REAGENT

A simple and cost effective spectrophotometric method is described for the determination of Meropenem (MP) in pure and pharmaceutical formulations. The method is based on the formation of dark yellow colored chromogen when the drug reacts with 1, 2 naphtho quinone -4-sulphonic acid sodium salt (NQS) reagent in alkalline medium. The method involves the addition of excess NQS of known concentration in the presence of 1.5 mL NaOH and the unreacted  NQS is determined by the measurement of the λ_max 449 nm, which was found to be the most suitable of several tests. This method was applied for the determination of drug contents in pharmaceutical formulations and enabled the determination of the drug in microgram quantities (0.5 to 3.0 mL). No interference is observed from excipients and the validity of the method was tested against reference method. The colored species has an absorption maximum at 449 nm for MP (Method A) and obeys beer’s law in the concentration range 0.02 – 0.12 mg/mL of MRP. The apparent molar absorptivity is 0.007 and sandell’s sensitivity is 7×10^-4. The slope is 0.1556 ± 0.0029 and intercept of the equation of the regression line is 0.0057 ± 0.0052. The optimum experimental parameters for the reaction have been studied and the validity of the described procedure was assessed. Statistical analysis of the results has been carried out revealing high accuracy and good precision. The proposed method was successfully applied for the determination of MP in pharmaceutical formulations.