Validation of an RP-HPLC method for simultaneously quantifying three UV filters encapsulated into nanostructured lipid carriers

Abstract

The development of sunscreens incorporating nanostructured lipid carriers (NLCs) is gaining traction in the cosmeceutical industry to enhance photoprotection. These innovative systems require robust and precise analytical methods to accurately quantify the chemical filters encapsulated within the lipid matrix. This study presents a fully validated RP-HPLC method specifically designed for the simultaneous quantification of three UV filters: diethylamino hydroxybenzoyl hexyl benzoate (DHHB), bis-ethylhexyloxyphenol methoxyphenyl triazine (BEMT), and ethylhexyl triazone (EHT), which were encapsulated in nanostructured lipid carriers (NLCs). The methods reported in the literature lack validation for nanostructure systems as they usually focus on exploring methods for free filters. Here, our approach was to optimize and validate an analytical method for NLCs, which demonstrated robustness, high sensitivity (LOD as low as 0.6 µg mL⁻¹), and compliance with the ICH guidelines. The method enabled the accurate and precise determination of filter extracted content, based on the extraction method, and encapsulation efficiency, supporting formulation optimization and industrial scalability by identifying a pool of interchangeable prototypes. Encapsulation efficiency of the UV-filters as the main response evaluated, which was interpreted through the critical quality attributes (CQAs) of values above 70%. Hence, the present study addresses a critical gap in the analytical methodologies for emerging nanoformulation technologies.