Determination of IR3535 in Topical Insect Repellents: A New HPLC-DAD Analytical Approach and Compliance Assessment

IR3535 is a synthetic active ingredient widely recognized for its efficacy in topical insect repellent formulations. Among commonly used repellent actives, it is distinguished by its favorable toxicological profile, making it suitable for use in children from 6 months of age. Ensuring the quality of insect repellents is a critical regulatory practice that directly contributes to public health protection. This study presents the development and validation of a novel, rapid 2.8-min retention time, and robust high-performance liquid chromatography method with diode array detection (HPLC-DAD) for the quantification of IR3535 followed by its application to the analysis of six commercial topical formulations. The method was validated in accordance with ICH Q2(R2) guidelines, demonstrating excellent linearity (R² = 0.996), precision (RSD < 2%), recovery range (98.2%-101.4%), selectivity, low limits of quantification (0.01 mg/mL) and detection (0.003 mg/mL), as well as robustness. This analytical tool enables reliable monitoring of IR3535 content, ensuring product safety, efficacy, and ANVISA compliance. Only 2 out of 6 commercial products analyzed met specifications for IR3535 content. These findings underscore the importance of implementing rigorous quality control practices to ensure regulatory adherence and to protect consumer health and rights.