Double dispersant-assisted ionic liquid dispersive liquid-liquid microextraction coupled with capillary electrophoresis for the determination of benzophenone-type ultraviolet filters in sunscreen cosmetic product

In this work, double dispersant-assisted ionic liquid dispersive liquid-liquid microextraction coupled with micellar electrokinetic chromatography was developed to determine four UV filters (benzophenone, 4-hydroxybenzophenone, 2,4-dihydroxybenzophenone, and 2-hydroxy-4-methoxybenzophenone). 1-Hexyl-3-methylimidazolium hexafluorophosphate was used as the extraction solvent. The main novelty of the present work was that acetonitrile-Triton X-114 was used as double disperser solvent. Parameters affected the extraction efficiency were investigated and optimized. Under the optimum conditions, enrichment factors were in the range of 25.3-40.5. The limits of detection and quantitation, calculated at a S/N of three and ten, were 3.9-6.7 ng/mL and 13.0-22.3 ng/mL. The linearity of the method was in the range of 0.02-2 mu g/mL for 2, 4-dihydroxybenzophenone and 4-hydroxybenzophenone, 0.01-2 mu g/mL for benzophenone and 2-hydroxy-4-methoxybenzophenone, with correlation coefficient (R-2) 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%.