A Robust Stability-Indicating RP-HPLC Method for Simultaneous Determination of Widely Used Pharmaceutical and Cosmetic Preservatives.

Pharmaceutical and cosmetic preservatives play a critical role in inhibiting microbial contamination, preventing chemical degradation, and maintaining product efficacy and safety throughout the shelf life. Given their functional importance, comparable to that of active pharmaceutical ingredients, it is essential to monitor their quality using advanced analytical techniques. Among the most commonly employed seven varieties of preservatives in industry are 2,4-dihydroxybenzoic acid, 4-hydroxybenzoic acid, 3,4-dihydroxybenzoic acid, benzyl alcohol, benzaldehyde, phenol, sodium benzoate, methylparaben, and propylparaben, either individually or in combination. The present study focuses on the development and validation of a stability-indicating, reverse-phase high-performance liquid chromatography method for simultaneous quantification of these seven preservatives and their impurities, benzaldehyde and phenol, a total of nine components. The method demonstrates high selectivity, sensitivity, accuracy, and precision, and meets the validation criteria outlined in International Council for Harmonization (ICH) guidelines. Optimal chromatographic resolution was achieved using a Phenomenex Luna C18 column, dual-wavelength UV detection at 254 and 230 nm, and a gradient mobile phase consisting of 0.1% orthophosphoric acid and acetonitrile. The method was established within a range of 1.5-45.0μg/mL concentration for all components. The validated method is suitable for routine quality control testing across various pharmaceutical and cosmetic formulations.