Determination and quantification of imiquimod and its related impurities from bulk drug production by high-performance liquid chromatography

Aim: A simple, selective, precise, and inexpensive reversed-phase high-performance liquid chromatography method has been developed and validated for the determination of imiquimod and related impurities such as 4-Chloro-1-isobutyl-1H-imidazo[4,5-c] quinoline, 1-isobutyl-1,5-dihydro-imidazo[4,5-c] quinolin-4-one, 1-isobutyl-4-methoxy-1H-imidazo[4,5-c] quinoline, and N-(1-isobutyl-1H-imidazo[4,5-c]quinolin-4-yl)-hydroxylamine-O-sulfonic acid. Materials and Methods: The method was followed using spectrophotometric detection at 260 nm with a Phenomenex Luna-RP-C18 column (250 × 4.6 mm, 5 μm) at a flow rate of 1.0 mL/min. The mobile phase consisted of deionized water spiked with 1% H3PO4 (Solvent A) and acetonitrile (Solvent B). Results and Discussion: Imiquimod and the common four impurities were eluted at different time intervals from 10 to 20 min. The developed method was validated in terms of system suitability, specificity, precision, linearity, accuracy, limit of detection, and limit of quantification. Conclusion: The mobile phase composition of 1% v/v H3PO4 in water: acetonitrile (90:10 v/v), showed good separation and resolution. Therefore, the proposed analytical procedure could be useful for regular monitoring, pharma manufacturing labs, and research scholars.