Cloud point-dispersive μ-solid phase extraction of hydrophobic organic compounds onto highly hydrophobic core-shell Fe₂O₃@C magnetic nanoparticles.
A novel two-step extraction technique combining cloud point extraction (CPE) with dispersive micro-solid phase extraction (D-μ-SPE) is presented in this work for the first time. The method involves initial extraction of the target analytes by CPE in the micelles of a non-ionic surfactant medium; then highly hydrophobic polysiloxane-coated core-shell Fe(2)O(3)@C magnetic nanoparticles (MNPs) are used to retrieve the micellar phase. In that manner, the micellar phase containing the analytes is the target of the D-μ-SPE step rather than the analytes directly. MNPs are then collected by the application of an adscititious magnetic field overcoming the need for specific steps associated with CPE such as centrifugation to separate the surfactant-rich phase, refrigeration of the condensed micellar phase to reduce its viscosity or appropriate apparatus that enable direct sampling of the surfactant-rich phase. A noteworthy feature of the method is the introduction of highly oleophilic MNPs, which afford rapid and quantitative mass transfer of the surfactant phase, as opposed to other more conventional hydrophobic nanoparticles. In that manner, fast and reproducible extraction is accomplished, lending improved analytical features compared to conventional CPE, such as reduced analysis time and relative inertness to surfactant concentration and equilibration temperature. The analytes were recovered from the surface of MNPs by ultrasound-assisted back-extraction in a water-immiscible organic solvent where analytes are readily partitioned but the surfactant has limited solubility, thus minimizing its interference during chromatographic detection. As an analytical demonstration, different UV absorbing chemicals with various physico-chemical properties were used as model organic compounds for optimizing the parameters associated with this novel two-step extraction approach. The proposed method, combining two different and efficient techniques, offers satisfactory analytical features in terms of repeatability (4.5-7.5%), reproducibility (7.0-14.9%) and accuracy (88.5-97.2%). Most importantly it poses as an alternative and fast method for sample pretreatment opening new insights in surfactant-mediated extractions.
Laboratory of Analytical Chemistry, Department of Chemistry, University of Ioannina, 45110 Ioannina, Greece. Electronic address: dgiokas@cc.uoi.gr.
Dimosthenis L
DL
Giokas
School of Chemical Engineering and Technology and State Key Laboratory of Robotics and System, Harbin Institute of Technology, Harbin 150001, China.
Qing
Q
Zhu
School of Chemical Engineering and Technology and State Key Laboratory of Robotics and System, Harbin Institute of Technology, Harbin 150001, China. Electronic address: panqm@hit.edu.cn.
Qinmin
Q
Pan
Departamento de Química Analítica, Facultad de Química, Universidad de Valencia, 46100 Valencia, Spain.
Alberto
A
Chisvert
D005618:Fresh Water / Q000737:chemistry; D006863:Hydrogen-Ion Concentration; D057927:Hydrophobic and Hydrophilic Interactions; D058185:Magnetite Nanoparticles / Q000737:chemistry*; D008956:Models, Chemical; D017830:Octoxynol; D009930:Organic Chemicals / Q000032:analysis / Q000737:chemistry / Q000302:isolation & purification*; D011092:Polyethylene Glycols / Q000737:chemistry; D015203:Reproducibility of Results; D052617:Solid Phase Microextraction / Q000379:methods*; D012997:Solvents / Q000737:chemistry; D013473:Sunscreening Agents
D058185:Magnetite Nanoparticles; D009930:Organic Chemicals; D012997:Solvents; D013473:Sunscreening Agents; D011092:Polyethylene Glycols; D017830:Octoxynol; C010615:Nonidet P-40