Ionic liquids intercalated in montmorillonite as the sorptive phase for the extraction of low-polarity organic compounds from water by rotating-disk sorptive extraction

• Published in: Analytica chimica acta 2017-02, Vol.953, p.23-31
• Main Authors: Fiscal-Ladino, Jhon A., Obando-Ceballos, Mónica, Rosero-Moreano, Milton, Montaño, Diego F., Cardona, Wilson, Giraldo, Luis F., Richter, Pablo
• Format: Article
• Language: English
• Subjects: Ammonium; Ammonium salts; Analytical chemistry; Assaying; Beta decay; Cations; Clay; Detection limits; Electron capture; Feature extraction; Galleries; Gas chromatography; GC-ECD; Intercalation; Ionic liquid; Ionic liquids; Ions; Materials selection; Montmorillonite; Organic compounds; PCB; PCB compounds; PCBs; Polarity; Pollutants; Polychlorinated biphenyls; Quaternary ammonium salts; Rotating disks; Rotating-disk sorptive extraction; Spectroscopic analysis; Wastewater
• ISSN: 0003-2670; 1873-4324
• DOI: 10.1016/j.aca.2016.11.067

Montmorillonite (MMT) clays were modified by the intercalation into their galleries of ionic liquids (IL) based on imidazolium quaternary ammonium salts. This new eco-materials exhibited good features for use as a sorptive phase in the extraction of low-polarity analytes from aqueous samples. Spectroscopic analyses of the modified clays were conducted and revealed an increase in the basal spacing and a shifting of the reflection plane towards lower values as a consequence of the effective intercalation of organic cations into the MMT structure. The novel sorbent developed herein was assayed as the sorptive phase in rotating-disk sorptive extraction (RDSE), using polychlorinated biphenyls (PCBs), representative of low-polarity pollutants, as model analytes. The final determination was made by gas chromatography with electron capture detection. Among the synthetized sorptive phases, the selected system for analytical purposes consisted of MMT modified with the 1-hexadecyl-3-methylimidazolium bromide (HDMIM-Br) IL. Satisfactory analytical features were achieved using a sample volume of 5 mL: the relative recoveries from a wastewater sample were higher than 80%, the detection limits were between 3 ng L−1 and 43 ng L−1, the precision (within-run precision) expressed as the relative standard deviation ranged from 2% to 24%, and the enrichment factors ranged between 18 and 28. Using RDSE, the extraction efficiency achieved for the selected MMT-HDMIM-Br phase was compared with other commercial solid phases/supports, such as polypropylene, polypropylene with 1-octanol (as a supported liquid membrane), octadecyl (C18) and octyl (C8), and showed the highest response for all the studied analytes. Under the optimized extraction conditions, this new device was applied in the analysis of the influent of a wastewater treatment plant in Santiago (Chile), demonstrating its applicability through the good recoveries and precision achieved with real samples. [Display omitted] •Clay modified with ILs successfully extracts PCBs from aqueous solutions.•A new RDSE sorbent is applied in the analysis of environmental samples.•A simple and green method is developed.•MMT-HDMIM-BR phase was more efficient than other commercial solid phases.•The novel MMT-HDMIM-BR sorbent is promising for determination of other low polarity analytes.