Double salts of ionic-liquid-based surfactants in microextraction: application of their mixed hemimicelles as novel sorbents in magnetic-assisted micro-dispersive solid-phase extraction for the determination of phenols

• Published in: Analytical and bioanalytical chemistry Vol. 407; no. 29; pp. 8753 - 8764
• Main Authors: Trujillo-Rodríguez, María J, Pino, Verónica, Anderson, Jared L, Ayala, Juan H, Afonso, Ana M
• Format: Journal Article
• Language: English
• Published: Berlin/Heidelberg Springer Berlin Heidelberg 01.11.2015; Springer Nature B.V
• Subjects: acetonitrile; adsorbents; Analytical Chemistry; Biochemistry; Bisphenol A; Bromides; Characterization and Evaluation of Materials; Chemistry; Chemistry and Materials Science; detection limit; evaporation; Extraction; Food Science; high performance liquid chromatography; ionic liquids; iron oxides; Laboratory Medicine; magnetic materials; Mathematical analysis; microextraction; Monitoring/Environmental Analysis; Nanomaterials; Nanoparticles; Optimization; Phenols; Research Paper; salts; solid phase extraction; Sorbents; Standard deviation; Surfactants; Ionic liquids; Double-salt ionic liquids; Dispersive solid-phase extraction; Mixed hemimicelles; Ionic-liquid-based surfactants; Magnetic nanoparticles
• ISSN: 1618-2642; 1618-2650
• DOI: 10.1007/s00216-015-9034-2

The use of mixed hemimicelles of ionic liquid (IL)-based surfactants in a magnetic-based micro-dispersive solid-phase extraction (m-μdSPE) approach is described. Not only is the symmetric monocationic IL-based surfactant 1,3-didodecylimidazolium bromide (C₁₂C₁₂Im-Br) studied for first time in m-μdSPE, but double-salt (DS) IL (DSIL)-based surfactants are also examined. Nine DSIL-based surfactants were formed by combination of C₁₂C₁₂Im-Br with other IL-based surfactants, including nonsymmetric monocationic and dicationic ILs combined at three different molar fractions. The analytical application was focused on the determination of a group of eight phenols, including bisphenol A, in water samples. The best results were obtained with the DSIL formed by C₁₂C₁₂Im-Br (molar fraction 0.5) and 1-hexadecyl-3-methylimidazolium bromide (C₁₆MIm-Br), after proper optimization of the overall method in combination with high-performance liquid chromatography (HPLC) and diode-array detection (DAD). The optimum conditions for 100 mL of water samples require a small amount (10 mg) of Fe₃O₄ magnetic nanoparticles, a low content (5.0 mg of C₁₂C₁₂Im-Br and 3.9 mg of C₁₆MIm-Br) of the selected DSIL, pH 11, a sonication time of 2.5 min, and an equilibration time of 5 min with the aid of NdFeB magnets, followed by elution of phenols, evaporation, and reconstitution with 0.5 mL of acetonitrile. The overall m-μdSPE–HPLC–DAD method is characterized for limits of detection down to 1.3 μg · L⁻¹, intraday relative standard deviations lower than 13 % (n = 3), and interday relative standard deviations lower than 17 % (n = 9), with a spiking level of 15 μg · L⁻¹; with enrichment factors between 15.7 and 141, and average relative recoveries of 99.9 %.