Determination of 31 Kinds of Sunscreen Agents Including Cinoxate in Sunscreen Cosmetics by HPLC

OBJECTIVE To establish a method for determination cinoxate and other 30 kinds of sunscreen agents in sunscreen cosmetics by HPLC.

METHODS Twenty-one fat-soluble sunscreen agents(1^#−21^#) were ultrasonically extracted by the mixed solution of methanol-tetrahydrofuran(1∶1), 10 kinds of water-soluble sunscreen agents(22^#−31^#) were ultrasonically extracted by the mixed solution of methanol-tetrahydrofuran-water(2∶3∶5) from the samples. Agilent Zorbax SB C₁₈(4.6 mm× 250 mm, 5 μm) column was used to separate cinoxate and other fat-soluble sunscreen agents(1^#−20^#), Agilent Zorbax SB C₁₈(2.1 mm× 100 mm, 3.5 μm) column was used to separate polysiloxane-15(21 ^#) , Waters Symmetry C₁₈(4.6 mm× 250 mm, 5 μm) column was used to separate 10 water-soluble sunscreen agents. Methanol-isopropanol-water, isopropanol-tetrahydrofuran-water, and methanol-acetonitrile-0.02 mol·L⁻¹ ammonium acetate solution(add phosphoric acid to adjust pH to 5.0) were used as mobile phase in gradient elution respectively. The flow rates were 1.2, 0.5, 1.0 mL·min⁻¹. The detection wavelengths were 358nm(7 ^#, 11 ^#) , 295 nm(23^#−25^#, 27^#−31^#), 311 nm(other components). The injection volumes were 5 µL(polysiloxane-15) and 10 µL(other component), the column temperature was set at 30℃.

RESULTS The linear relationships(r>0.9999) of 31 sunscreen agents were good in corresponding concentration range. The limit of detection were in the range of 0.002%−0.02%. The recoveries of two substrates at three different supplemental levels ranged from 92.4% to 110.3%, with the RSDs of 0.02%−4.5%. Forty batches of domestic and imported sunscreen cosmetics were determined by this method, 17 kinds of approved sunscreen agents were detected, of which polysiloxane-15 were detected in 10 batches of samples. By comparing with the current method in Safety and Technical Standards for Cosmetics(2015 edition) , it was found that the extraction efficiency of fat-soluble sunscreen agents was superior to the current method, the stability of drometrizole trisiloxan was improved, cinoxate, polysiloxane-15 and other 7 kinds of sunscreens were added.

CONCLUSION This method is accurate, sensitive and reliable, which can be used for the detection and analysis of sunscreen in sunscreen cosmetics.