Validation of a spectrophotometric method to determine the content of octyl salicylate in sunscreen cosmetic products singularly and in combination with physical ultraviolet filters of zinc oxide and titanium dioxide

personАвтори: N. Vassileva, S. Uzunova, А. Таchev


For ultraviolet (UV) filter of Octyl salicylate, as a component of cosmetic products, there exists a maximum applicable concentration indicated in legislation up to 5%. The observation of the mandatory limits has to be strictly controlled. On the other hand, the establishment of real content of the UV filter lower than the declared in cosmetic formulation is an indication for lack of safety protection against UV filters declared on the label. There is no referent method for determination of UV filter of Octyl Salicylate in sunscreen products. The aim of this study is to develop and validate a useful spectrophotometric method for its determination. There has been developed and validated a spectrophotometric method for determination of UV filter of Octyl salicylate in sunscreens, which is applied both singularly and in combination with physical filters of Zinc oxide and Titanium dioxide. The method is based on the capacity of solutions of Octyl salicylate in ethanol to absorb UV filters with wave length of 305 nm. The value of light absorption measured at this wave length is proportional to the concentration of Octyl salicylate. A total of 433 studies were performed, on the basis of which, the parameters derived of the method are: selection – specific absorption at 305 nm; linearity from 1,25 to 100 μg/cm3 (from 0,625 to 50,0%); stability for 24-hour duration at concentration of Octyl Salicylate 10 μg/cm3 – RSD = 0,55%; repeatability – by 4% of Octyl Salicylate – SD – 0,0479%; reproducibility – by 4% of Octyl salicylate – RSD under conditions of repeatability – 1,21%; yield at concentration of Octyl Salicylate in cosmetic product by 2% – 97,62% (95,56-102,22%), by 4% – 98,26% (96,11-101,67%). For the different types of cosmetic products, there have been established: working range – from 0,09 to 12,5%, limits of detection (LOD) – from 0,07 to 0,75%, limits of quantification (LOQ) – from 0,09 to 0,82%. The spectrophotometric method developed and validated for determination of UV filter of Octyl salicylate in sunscreen products is fast, sensitive, and reproducibile, of good accuracy and does not require sophisticated and expensive apparatuses. It can be applied easily for the control of sunscreen cosmetic products.

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