Analysis And Photostability Study Of Selected Ultraviolet Absorbents In Sunscreens

Ultraviolet absorption agents are active materials which have to bask in effect of sunscreen.They are widely used in cosmetics because they can effectively protect the body from excess ultraviolet radiation.However,ultraviolet absorption agents could produce certain harm to human body if they are added too much.Therefore,it is very important to detect the contents of ultraviolet absorption agents.In addition,ultraviolet absorption agents have characteristic of photosensitive-sex,which has important influence on cosmetics in sunscreen.Therefore,it is extremely essential to study the light stability of ultraviolet absorption agents as well as their photodegradation by-products.In this work,we firstly review the current situation of sunscreen as well as the classification,test status and light stability of ultraviolet absorption agent,and then set up the liquid detection methods of the cosmetics ultraviolet absorption agents in different conditions.The light stability of ultraviolet absorption agents were first analyzed by high performance liquid chromatography(HPLC)and gas chromatography mass spectrometry(GC-MS),which provides a certain method to evaluate the effect and safety of the prevent bask in cosmetics.We detect the content of the ultraviolet absorption agents in cosmetics,explore the light stability of the ultraviolet absorption agents(BP-3,OC,OD-PABA,IAMC,EHMS)which are added to in higher frequency.Specific contents are as follows:(1)Based on the methanol/THF as mobile phase and extraction solvent,Agilent ZORBAX SB C18(4.6 mm × 150 mm,3.5 μ m)for chromatographic column,we detected 14 kinds of ultraviolet absorption agents(except phenyl benzene and sulfonated sulfonic acid)after liquid phase separation.They from 30 kinds of sunscreen and 10 kinds of cosmetics which could not prevent bask.Results showed that 14 kinds of ultraviolet absorption agents could be completely separated within 30 min,peak area and the concentration was of good correlation coefficient(r>0.9990)in 1～500 mg/L concentration range,the detection limits of the qualitative and quantitative methods were all of 0.002～0.1 mg/L,average labeled recoveries were 93.7%～112.6%in 20 to 500 mg/L concentration range and the precisions of<5%.Sample results that,the added ultraviolet absorption agents exist exceed bid phenomenon and the kinds of actual added ultraviolet absorption agents are not as same as the label stating.Among them,2-ethylhexyl4-methoxycinnamate,Octocrilene and Homosalate exist exceed bid phenomenon,Bis-ethylhexyloxyphenol methoxyphenyl triazine and Benzophenone-3 exist phenomenon of the kinds of actual added ultraviolet absorption agents are not as same as the label stating.Meanwhile,in 10 kinds of cosmetics which could not block sun(most of whom are modified kind of cosmetics,such as segregation frost,BB frost),several kinds of commonly used ultraviolet absorption agents of sunscreen are added,such as:2-ethylhexyl4-methoxycinnamate,Octocrilene and Benzophenone-3,etc.(2)This work first adopted methanol as mobile phase and extraction solvent,Agilent ZORBAX Eclipse XDB-C8 column(4.6 mm x 250 mm,5 μ m)as separation column for liquid phase separation detection 12 kinds of ultraviolet absorption agents(except UVT-150,Bis-ethylhexyloxyphenol methoxyphenyl triazine and Ultraviolet absorbent UV-360)in the sunscreen,and the results showed that the 12 kinds of ultraviolet absorption agents were entirely separated within 24 min;peak area and the concentration were good correlation coefficient(r>0.9995)from 0.5 to 500 mg/L concentration range;the detection limits of the method of qualitative and quantitative were 0.002～0.1 mg/L;the average labeled recoveries were 97.4%～107.5%in 20 to 200 mg/L concentration range;the days of precision(n = 5)and daytime precision(n=3)were less than 5%.Meanwhile,whether to choose acetonitrile or methanol,we found that acetonitrile was not suitable for elution of ultraviolet absorption agents,the research result indicated that:adopt methanol as mobile phase,the separating time was shorter,linear relationship was better,the experimental operations were simpler and the operating personnels were in less damage.(3)This work used HPLC and GC-MS to research the photostability of 5 kinds of commonly used ultraviolet absorption agents.After being illuminated by ultraviolet radiation,BP-3,OC and OD-PABA were analysed by HPLC and the results indicated that their concentrations did not exist too big changes after being illuminated.On the contrary,through the HPLC analysis,we found that IAMC and EHMS concentrations strikingly existed changes.We also found that the photodegradation materials of IAMC and EHMS may be their isomerides by GC/MS.