Study On The Stability Of Physical And Chemical Quality Of Sunscreen Cosmetic Emulsion

As a kind of special-purpose cosmetical products,the sunscreen cosmetics have become one of the daily necessary protective products for most people becase of their effective protection of human body from excessive ultraviolet rays.According to their protection mechanisms,they can be divided into physical and chemical two types.The physical sunscreen cosmetics owe such a high level of quality safety wherease the chemical sunscreen cosmetics will lead some great potential risks to the human skin or health when they conduct a close and wide contact with the human body under the influence of ultraviolet absorbers.Therefore,in terms of related risk assessments,in addition to the consideration of comprehensive qualities(contact safety,protection quality,and skin irritation etc),the degree of quality maintenance should also be investigated,that is,the physical and chemical quality stabilities,which is always considered as a focus by the consumers and cosmetical formulators.However,at present,most of the stability researches are pretty shallow,and lack a comprehensive inspection system as well as related scientific and objective stability data.Besides,most of the UV absorbers are instable,which directly impact the maintance of the claimed sunscreen efficacy and shelf life.Therefore,it is of great necessity to improve the research system on quality stability and have a understanding of the probable chemical degradation situation of UV absorbers in sunscreen cosmetic emulsions.The specific research contents of this paper are as follows:1.A stability research system was established for W/O and O/W sunscreen cosmetic emulsions which were accelerated by 45 °C,75% RH and 4 °C,24h;45 °C,24 h two conditions,and monitored by four quality indicators,that is sunscreen absorbers content,odor,appearance,color,and physical stability.The results show that the established HPLC method for simultaneous detection of 8 sunscreen agents in sunscreen cosmetics meets all the requirements of methodological verification and can be used for quantitative analysis of these 8 UV absorbers in different kinds of sunscreen cosmetics.While,the four quality indicators vary with the type of product and the added ultraviolet absorbers.2.A UPLC-Q-TOF/MS confirmation method for the stability of 8 ultraviolet absorbers in sunscreen cosmetic emulsions was established.The research results show that this method is in high accuracy,and can be used to confirm the stability of UV absorbers in sunscreen emulsions as well as analysis on degradation products,providing a reliable reference for the investigation of the stability of UV absorbers in sunscreen products.3.As an ovrall analyzed technology,the ATR-FTIR was adopted to explore its application in the field of identification of cosmetics and the monitoring of physicial and chemical quality stability.The results show that this method is fast,simple,accurate and practical,it can be used not only for identification of sunscreen lotions with slight differences,but also for monitoring the stability conditons of cosmetic products,especially the cosmetics without specific active compounds,providing a scientific and reliable method for its shelf-life prediction.