285 J. Cosmet. Sci., 73, 285–296 (September/October 2022) Address all correspondence to Shanta Kumari Adiki, skatakam9@gmail.com Chemometric-Assisted, Stability-Indicating Reversed- Phase High-Performance Liquid Chromatography Method for Simultaneous Quantitation of Resorcinol, p-phenylenediamine, and m-aminophenol in Commercial Hair Dyes SHANTA KUMARI ADIKI, PRAKASH KATAKAM AND FATHI H. ASSALEH Department of Pharmaceutical Analysis, Nirmala College of Pharmacy, Mangalagiri, Guntur, Andhra Pradesh, India (S.K.A.) Department of Pharmaceutics, Indira College of Pharmacy, Nanded, Maharashtra, India (P.K) Department of Chemistry, Libyan Academy for Postgraduate Studies, Tripoli, Libya (F.H.A) Accepted for publication December 22, 2022. Synopsis This work aims to develop a chemometric-assisted, stability-indicating reversed-phase high-performance liquid chromatography method, optimized by a combined D-optimal design approach of response surface methodology, for simultaneous quantitation of resorcinol, p-phenylenediamine, and m-aminophenol in cosmetic hair dyes. The reversed-phase high-performance liquid chromatography method was developed for routine estimations of resorcinol, p-phenylenediamine, and m-aminophenol in cosmetic hair dyes. The chromatographic conditions (i.e., flow rate, ratios of mobile phase composition, and run time) were optimized by a combined D-optimal design approach. The retention times for the estimation of resorcinol, p-phenylenediamine, and m-aminophenol were found to be 7.273–7.232, 9.976–10.114, and 11.639–11.735 minutes, respectively. The linearity for resorcinol, p-phenylenediamine, and m-aminophenol were obtained in the range of 10–150 ppm with correlation coefficients (r2) 0.9991, 0.9994, and 0.993, respectively. The compound amounts estimated by the proposed method were in agreement with the labeled claim. We used a minimal amount of organic solvents in the mobile phase and thus could be considered more eco-friendly over existing methods. The proposed method could be employed for routine, quality control analysis of the titled compounds in combined hair dye formulations. Optimization of chromatographic conditions by response surface methodology adds a new dimension to analytical method development. INTRODUCTION Quality control of any type of product is of paramount importance to ensure efficacy and safety of the products for consumer use and acceptance. It is also desirable to determine whether all features of a product will be properly maintained during its shelf life. A wide