Multivariate optimization of dispersive liquid-liquid microextraction using ionic liquid for the analysis of ultraviolet filters in natural waters.

In this work, a vortex-assisted dispersive liquid-liquid microextraction method, using an ionic liquid as the extracting solvent was developed, for the simultaneous analysis of three UV filters in different water samples. The extracting and dispersive solvents were selected in a univariate way. Then, the parameters such as the volume of the extracting and dispersive solvents, pH and ionic strength were evaluated using a full experimental design 2, followed by Doehlert matrix. The optimized method consisted of 50 μL of extracting solvent (1-octyl-3-methylimidazolium hexafluorophosphate), 700 μL of dispersive solvent (acetonitrile) and pH of 4.5. When combined with high-performance liquid chromatography, the method limit of detection ranged from 0.3 to 0.6 μg L, enrichment factors between 81 and 101%, and the relative standard deviation between 5.8 and 10.0%. The developed method demonstrated effectiveness in concentrating UV filters in both river and seawater samples, being a simple and efficient option for this type of analysis.