In-syringe ultrasound-assisted dispersive liquid–liquid microextraction for the fluorescent determination of aluminum in water and milk samples

Abstract

In this work, a simple, fast and environmentally friendly procedure to determine aluminum in water and milk samples was developed. Aluminum is an element that can be found in packaging as well as in different containers. The World Health Organization has fixed limits for the presence of aluminum in drinking water and food. Therefore, it is important to develop new reliable procedures for its determination. This new procedure was performed by means of an in-syringe dispersive liquid–liquid microextraction using a mixture of an ionic liquid ([Bmim]PF6) as extractant, and a surfactant (Triton X-100) as dispersive solvent. The dispersive liquid–liquid microextraction was assisted by ultrasound. 8-hydroxyquinoline was used as a chelating agent with a subsequent online spectrofluorometric detection. Under the optimal conditions, the preconcentration factor was 200, and the recovery values were between 91.4 and 115.6 % (n = 3) with satisfactory % Relative Standard Deviation values, which indicate appropriate accuracy and precision. The limits of detection were 1.7 and 5.5 μg L−1, and the limits of quantification were 5.7 and 18.4 μg L−1 for water and milk samples, respectively. The obtained results demonstrated the applicability of the proposed procedure for the determination of aluminum in water and milk samples. The main advantage of this research was the reduction of the extraction time (90 s) due to the application of ultrasound energy, which allowed for improved extraction and pre-concentration steps. In addition, the procedure was analyzed using the software AGREE metric, and the overall score obtained was compared with other procedures found in the literature for aluminum determination.