Simultaneous determination of two UV filters (octylmethoxycinnamate, octylsalicylate) in sunscreen creams by high performance thin layer chromatography (HPTLC)

Octylmethoxycinnamate (OMC), octylsalicylate (OS) are UV filters commonly used in sunscreen creams for skin protection against UV radiations. In this study, an HPTLC method was developed and validated for simultaneous determination of OMC and OS in sunscreen creams. The method was carried out using an silica gel 60 F254 thin layer plate (20 cm × 10 cm) with a mixture of cyclohexane - aceton (10:1, v/v) as mobile phase. Samples were applied on thin layer plate as 4-mm bands with applied volume at 7.0 µL per band and the distance between two consecutive bands was 9 mm. The chromatograms were developed over a distance of 80mm, then scanned and recorded at 307 nm for peak detection and calculation of peak area. The method was fully validated according to requirements on analytical method performance of AOAC International. The linearity ranges of the method were from 17.9 to 32.2 µg/mL for OMC and from 16.3 to 29.4 µg/mL for OS, respectively, and its accuracy (recovery rate from 97.4% to 102.2% for OMC and from 98.0% to 102.4% for OS) and its precision (RSD ≤ 2.6% for OMC and ≤ 2.4 % for OS) were sufficient for simultaneous determination of these two UV filters. Therefore, validation results confirmed its reliability and suitability for intended application. The method was employed to determine the content of OMC and OS in commercial sunscreen creams. Keywords: HPTLC, UV filter, sunscreen cream, octyl methoxycinnamate, octyl salicylate