Resumo:
Miniaturization methods have achieved prominence in the configurations of analytical methods, with the main objective of reducing the use of harmful reagents released into the environment, in addition to reducing extraction time. In this work, a method based on ultrasound-assisted dispersive liquid-liquid microextraction (USDMLLE) was developed for the determination of mercury by UV-Vis molecular absorption spectrophotometry. The procedure is based on the use of a mixture of the Ionic Liquid, 1-hexyl-3-methylimidazolium hexafluorophosphate [C6MIM][PF6], as an extracting solvent, dithizone as a complexing agent and ultrasonic radiation as a disperser in an aqueous solution containing mercury. After turbidity, the mixture is centrifuged to separate the phases. Subsequently, the enriched phase is collected and the mercury content is measured by UV-Vis molecular absorption spectrophotometry. The pH of the buffer solution, the concentration of the complexing agent, and the volume of the ionic liquid were the variables optimized using a multivariate strategy. The detection and quantification limits, calculated under optimized conditions, were 0,031 μ.L-1 and 0,103 μ.L-1, respectively. The enrichment factor obtained was 403 times. The procedure was applied to the determination of mercury in samples of diphtheria, tetanus, whooping cough – DTP and hepatitis A and B vaccines that use thimerosal as preservatives. The proposed method is simple, fast, efficient and does not use organic solvents in the liquid-liquid extraction process.
