Sustainable ionic liquid-assisted cloud point extraction for enrichment of trace copper(II) in water and food samples prior to spectrophotometric determination

Abstract

Abstract This work introduces a novel, cost-effective, and sustainable ionic liquid–assisted cloud point extraction (IL-CPE) technique for the enrichment and spectrophotometric quantification of trace copper(II) at 436 nm. The method employs the complexation of Cu(II) with (Z)-4-bromo-2-(((2-hydroxyphenyl)imino)methyl)phenol at pH 6.5, succeeded by extraction with 1-butyl-3-methylimidazolium hexafluorophosphate and Triton X-114. Under optimal circumstances, the approach exhibited remarkable linearity (2.0–300 µg L⁻¹, R 2  = 0.9997), substantial sensitivity with a preconcentration and enrichment factors 100 and 12.5, respectively, and a minimal detection limit of 0.6 µg L⁻¹. Precision and reliability of the novel IL-CPE method was validated by low relative standard deviation for 100 and 200 µg L⁻¹ ( n  = 10) was 1.6% and 2.0%, respectively, and accuracy was substantiated by the use of certified reference materials and actual environmental samples, encompassing water and food matrices. Moreover, the method’s environmental effect was meticulously assessed utilizing several Green Analytical Chemistry metrics (AGREE, AGREEprep, ComplexMoGAPI, AGSA) and practical indices (BAGI, CACI). The evaluation via the RGB algorithm and Carbon Footprint Reduction Index (CaFRI) verifies that this method is a sustainable, eco-friendly, and very dependable option for regular trace metal detection.