Extraction and preconcentration of trace Al and Cr from vegetable samples by vortex-assisted ionic liquid-based dispersive liquid–liquid microextraction prior to atomic absorption spectrometric determination

• Published in: Food chemistry 2018-04, Vol.245, p.586-594
• Main Authors: Altunay, Nail, Yıldırım, Emre, Gürkan, Ramazan
• Format: Article
• Language: English
• Subjects: Aluminum; Chromium; Flame atomic absorption spectrometry; Ionic liquid; Microextraction; Vegetables
• ISSN: 0308-8146; 1873-7072
• DOI: 10.1016/j.foodchem.2017.10.134

•The variables affecting microextraction efficiency were extensively evaluated and optimized.•CTAB was used as ion pair to convert anionic metal complexes to the hydrophobic complexes.•The accuracy was evaluated by the analysis of a certified reference material.•Ionic liquid-based dispersive liquid–liquid microextraction was assisted by means of vortex.•1-Butyl-3-methylimidazolium bis (trifluorosulfonyl) imide was used as an extractant. In the study, a simple, and efficient microextraction approach, which is termed as vortex-assisted ionic liquid-based dispersive liquid–liquid microextraction (VA-IL-DLLME), was developed for flame atomic absorption spectrometric analysis of aluminum (Al) and chromium (Cr) in vegetables. The method is based on the formation of anionic chelate complexes of Al(III) and Cr(VI) with o-hydroxy azo dye, at pH 6.5, and then extraction of the hydrophobic ternary complexes formed in presence of cetyltrimethylammonium bromide (CTAB) into a 125 μL volume of 1-butyl-3-methylimidazolium bis(trifluorosulfonyl)imide [C4mim][Tf2N]) as extraction solvent. Under optimum conditions, the detection limits were 0.02 µg L−1 in linear working range of 0.07–100 µg L−1 for Al(III), and 0.05 µg L−1 in linear working range of 0.2–80 µg L−1 for Cr(VI). After the validation by analysis of a certified reference material (CRM), the method was successfully applied to the determination of Al and Cr in vegetables using standard addition method.