Spectrophotometric determination and spectroscopic studies on Schiff base and charge transfer complex of ketorolac tromethamine

Abstract

Background: Ketorolac tromethamine is a versatile analgesic drug used extensively for the treatment of fever and moderate to severe pain. It is a potent non-steroidal anti-inflammatory drug that extends opioid-level analgesia to patients. Two new selective methods are proposed for spectrophotometric determination of ketorolac tromethamine (KT) in pure and pharmaceutical formulation. Methods: The determination procedures are based on the condensation reaction of KT with 2,4-dinitrophenylhydrazine (DNPH) in strongly alkaline medium resulting in the formation of red-colored hydrazones which is quantitated at 424 nm for method A and method B involves the charge transfer reaction between KT as electron donor and 7,7′,8,8′-tetracyanoquinodimethane (TCNQ) as π-acceptor to form dark green-colored complex which is measured at 842 nm. Results: Linear correlation is obtained in the range 0.50–18.50 μg mL−1 and 2.00–50.00 μg mL−1 with detection limits of 0.1579 and 0.3721 μg mL−1 for method A and method B, respectively. The optimum analytical conditions are analyzed, and the proposed assay is validated as per the ICH guidelines. Conclusions: The developed methods are effectively applied to the determination of KT in tablets, injections, and ophthalmic formulations with good percentage recoveries. The final reaction products are characterized by spectral analysis (FT-IR and 1H NMR). In addition, the surface morphology of the reaction products are also studied using scanning electron microscopy.