Ultrasonic-assisted ionic liquid-based microextraction for preconcentration and determination of aluminum in drinking water, blood and urine samples of kidney failure patients: a multivariate study

Abstract

We have developed a simple ultrasonic-assisted ionic liquid-based microextraction (US-ILME) method for trace levels of aluminum (Al³⁺), in water, blood, and urine samples, followed by atomic absorption spectrometry with a nitrous oxide–acetylene flame. An ionic liquid, 1-hexylpyridinium hexafluorophosphate [Hpy][PF₆], was used as the extraction solvent, and 8-hydroxyquinoline (oxine), was used as the Al³⁺ chelating agent. A multivariate strategy was employed to evaluate five factors/variables (concentration of the chelating agent, pH, amount of ionic liquid, sonication time and centrifugation time) at once, whereas a central composite design was used to find the optimum values of the significant variables. The multivariate strategy was used to estimate the optimum values of experimental factors that influence the efficiency of US-ILME. Under the optimum experimental conditions, the limit of detection (3 s) and enrichment factor were 0.66 μg L⁻¹ and 113, respectively. The relative standard deviation (RSD) for six replicate determinations of 10 μg L⁻¹ of Al³⁺ was 1.7%. The method was validated by the analysis of certified reference materials and applied successfully to the determination of Al³⁺ in different types of drinking water, and in blood and urine samples of kidney failure patients. The data indicated that the levels of Al³⁺ were significantly higher in kidney failure patients compared with healthy referents (p < 0.01).