Air assisted emulsification liquid-liquid microextraction based on deep eutectic solvent for preconcentration of methadone in water and biological samples.

Nowadays, a deep eutectic solvent (DES) has recently been considered as a green ion liquid analogue. In this study, a new compound of DES has been synthesized as an extraction solvent in air assistedemulsification liquid-liquid microextraction method (DES-AAELLME) for preconcentration and extraction of methadone followed by gas chromatographyflame ionization detector (GC-FID). To obtain an efficient water-miscible deep eutectic solvent, choline chloride (ch-cl) and 5,6,7,8-Tetrahydro-5,5,8,8-tetramethylnaphthalen-2-ol (TNO) were mixed at a molar ratio of 1:2 and tetrahydrofuran (THF) was used as a demulsifier solvent into homogeneous solution for providing a turbid state. The solution was rapidly sucked up and injected 10 times using a 10-mL glass syringe to enhance the turbidity of solution and disperse the aggregated DES droplets into aqueous phase. Some important parameters affecting extraction recovery were investigated. Under optimum conditions, the calibration curve was linear in the concentration range from 2 to 8000µgL-1. The limit of detection and the limit of quantification were found 0.7µgL-1 and 2.3µgL-1 respectively with preconcentration factor of 270. The precision, as the relative standard deviation (RSD) (n=6), was <6% respectively. This method was successfully applied to determine methadone in water and biological samples with an appropriate recovery about 98.4-101.2%.

Development of air assisted liquid phase microextraction based on switchable-hydrophilicity solvent for the determination of palladium in environmental samples.

A novel switchable-hydrophilicity solvent (SHS) in combination with air-assisted liquid-liquid microextraction (AALLME) which called AA-SHS-LPME, has been applied for preconcentration of Pd(II). A water-immiscible solvent, Triethylamine (TEA), was used as a green switchable solvent that switched reversibly between one form that was miscible with water to another that formed a biphasic mixture with water. CO2 was used as a stimulus for triggering the transformation to the water-miscible form and removal of CO2 to achieve the reverse. Separation was carried out by addition of sodium hydroxide, which produced a change on the ionization state of amine. AALLME led to the rapid formation of fine droplets of the extractant in the aqueous solution, and the contact surface between both immiscible liquids was significantly enlarged. Detection limit value, preconcentration factor and relative standard deviation (RSD, n=10) were found 0.07µgL(-1), 64 and 3.5% respectively. The recovery of the analyte in water, road dust and catalytic converter samples was in the range of 98.3-103.2%. The obtained results indicated that the developed method could be an efficient analytical method for the routine analysis in the environmental field.

Magnetic Graphene-Dispersive Solid-Phase Extraction for Preconcentration and Determination of Lead and Cadmium in Dairy Products and Water Samples.

A magnetic-dispersive solid-phase extraction (MDSPE) was used for precocentration of Pb(II) and Cd(II) in milk, yoghurt and water samples. An appropriate amount of suspension containing the magnetic graphene and Triton X-114 was injected rapidly into the aqueous sample by a syringe. Triton X-114 was used to achieve stable suspension of graphene in solution. The structure of the resulting products was confirmed by Fourier transform infrared (FT-IR) spectra, X-ray diffraction (XRD) spectrometry. The effects of various parameters were studied. A detection limit of 0.16 and 0.50 µg L(-1) for Cd(II) and Pb(II) was obtained, respectively. The relative standard deviations (RSDs, n = 10) of 50 µg L(-1) of Pb and Cd were 3.3 % and 2.1 %, respectively. The results indicated that the present method can be reliably used for determination of Pb(II) and Cd(II) in dairy products and water samples with good recoveries.