Ionic Liquid Dispersive Liquid Phase Microextraction Coupled With Capillary Electrophoresis For The Determination Of Ultraviolet Filters And Preservatives In Cosmetics

With the rapid development of economic society, the cosmetic industry is developing rapidly, and become an indispensable part of human life. People’s living standard enhances unceasingly, and the demand for cosmetics is becoming more and more high. The application of various chemicals, has a significant influence on people’s healthy life. Therefore, to establish a simple, cheap, effective and sensitive detection method is of great significance.Capillary electrophoresis(CE), due to its separation efficiency, low cost, environment friendly, automatic fast, and many other advantages, is widely applied to the analysis of organic compounds in a variety of fields. Simple and effective sample preconcentration technology is the important guarantee of a reliable analysis method. Dispersive liquid-liquid microextraction(DLLME) technique was established by Rezaee et al., which is a new type of liquid phase microextraction technique. The target analytes were extracted, by using the extraction solvent, dispersive solvent and the sample solution to form turbid solution. It overcomes the tedious operation, a large number of organic solvent consumption, low extraction efficiency and many shortcomings of the traditional liquid-liquid extraction,obtaining more and more attentions. It was successfully combined with gas chromatography,liquid chromatography, atomic absorption spectrum, capillary electrophoresis and other testing means, and was used to detect various trace organic compounds, metals and other substances.Ionic liquid(IL) is a new development of green solvent in recent years, and successfullyapplied in dispersive liquid-liquid microextraction, obtaining fast development. In this article,dispersive liquid microextraction was combined with capillary electrophoresis for the determination of ultraviolet filters and preservatives in cosmetics. Ionic liquid was used as extraction solvent, using double dispersant, or through the method of ultrasound and the change of the temperature,and ionic liquids were scattered effectively in the sample solution,extracting the analytes. The concrete research contents are as follows:Double dispersant-assisted ionic liquid dispersive liquid-liquid microextraction coupled with CE was developed to determine four benzophenone-type UV filters. IL of [C6MIM][PF6]was used as the extraction solvent, and acetonitrile-Triton X-114 was used as double disperser solvent. Parameters affected the extraction efficiency were investigated and optimized, including type of the extraction solvent and disperser solvent, concentration of surfactant, volume of the extraction solvent and disperser solvent, salt addition, effect of p H,and centrifugation time. Under the optimum conditions, LOD and LOQ of the four benzophenone-type UV filters were 3.9-6.7 ng m L-1and 13.0-22.3 ng m L-1, respectively.The linearity of the method was in the range of 0.02 - 2 μg m L- 1for 2,4-dihydroxybenzophenone and 4-hydroxybenzophenone, 0.01-2 μg m L-1for benzophenone and 2-hydroxy-4-methoxybenzophenone, with correlation coefficient(R2) of 0.9984-0.9991.The proposed method was successfully applied to the determination of four benzophenone-type UV filters in six kinds of sunscreen cosmetic products, with yielded relative recoveries ranging from 80.2 to 117.7%.Ultrasound-assisted temperature-controlled ionic liquid dispersive liquid microextraction coupled with capillary electrophoresis was developed for the determination of four parabens.Ionic liquid of [C8MIM][PF6] was used as extraction solvent, and ionic liquids were scattered effectively in the sample solution through the method of ultrasound and the change of the temperature. Parameters affecting the extraction efficiency were optimized, including volume of ionic liquid, heating temperature, ultrasonic time, extraction time, sample p H, ionic strength and centrifugation time. Under the optimized conditions, LOD and LOQ of the fourparabens were 0.45–0.72 ng m L-1and 1.50–2.40 ng m L-1, respectiely. Intra-day and inter-day precisions were in the range of 5.4–6.8% and 7.0–8.7%, respectively. The recoveries of parabens in real samples at different spiked levels ranged from 71.9% to 119.2% with relative standard deviations less than 9.5%.