Quantification of sunscreen ethylhexyl triazone in topical skin-care products by normal-phase TLC/densitometry

Abstract

Ethylhexyl triazone (ET) was separated from other sunscreens such as avobenzone, octocrylene, octyl methoxycinnamate, and diethylamino hydroxybenzoyl hexyl benzoate and from parabens by normal-phase HPTLC on silica gel 60 as stationary phase. Two mobile phases were particularly effective: (A) cyclohexane-diethyl ether 1:1 (v/v) and (B) cyclohexane-diethyl ether-acetone 15:1:2 (v/v/v) since apart from ET analysis they facilitated separation and quantification of other sunscreens present in the formulations. Densitometric scanning was performed at 300nm. Calibration curves for ET were nonlinear (second-degree polynomials), with R 0.998. For both mobile phases limits of detection (LOD) were 0.03 and limits of quantification (LOQ) 0.1g spot-1. Both methods were validated. Copyright © 2012 Anna W. Sobanska and Jaroslaw Pyzowski.