In-syringe dispersive liquid-liquid microextraction using deep eutectic solvent as disperser: Determination of chromium (VI) in beverages.

A novel approach for dispersive liquid-liquid microextraction based on the use of deep eutectic solvent as a disperser was presented for the first time. The procedure was automated based on an in-syringe flow system coupled with UV-Vis detection and demonstrated by the determination of chromium (VI) in beverages. This analytical task was used as a proof-of-concept example. The automated extraction procedure involved the aspiration of aqueous sample into a syringe pump with homogeneous mixture of extraction solvent (1-oсtanol) and deep eutectic solvent (tetrabutylammonium bromide - formic acid) containing color-forming reagent (1,5-diphenylcarbazide). This led to decomposition of deep eutectic solvent in aqueous phase resulting in dispersion of extraction solvent, oxidation of 1,5-diphenylcarbazide to 1,5- diphenylcarbazone in the presence of chromium (VI), and formation of colored chromium (III) complex with 1,5-diphenylcarbazone and its fast extraction. In this case composition of deep eutectic solvent played a key role for analyte extraction. Tetrabutylammonium bromide promoted mass transfer between aqueous phase and the extraction solvent droplets as a salting out agent, bromide ion acted as an ion-pare agent for analyte complex extraction, formic acid provided required pH value for analyte complex formation. Under the optimal conditions the limit of detection, calculated from a blank test based on 3s, was 0.2 μg L-1. The automated dispersive liquid-liquid microextraction using deep eutectic solvent as disperser can be considered as an available, efficient, rapid and environmentally friendly sample pretreatment approach.

Shishov A ，Terno P ，Moskvin L ，Bulatov A ... -  《-》

Deep eutectic solvent decomposition-based microextraction for chromium determination in aqueous environments by atomic absorption spectrometry with electrothermal atomization.

Shishov A ，Terno P ，Bulatov A 《-》

Deep eutectic solvent based homogeneous liquid-liquid extraction coupled with in-syringe dispersive liquid-liquid microextraction performed in narrow tube; application in extraction and preconcentration of some herbicides from tea.

A homogeneous liquid-liquid extraction performed in narrow tube coupled to in-syringe-dispersive liquid-liquid microextraction based on deep eutectic solvent has been developed for the extraction of six herbicides from tea samples. In this method, sodium chloride as a separation agent is filled into the narrow tube and the tea sample is placed on top of the salt. Then a mixture of deionized water and deep eutectic solvent (water miscible) is passed through the tube. In this procedure, the deep eutectic solvent is realized as tiny droplets in contact with salt. By passing the droplets from the tea layer placed on the salt layer, the analytes are extracted into them. After collecting the solvent as separated layer, it is mixed with another deep eutectic solvent (choline chloride/butyric acid) and the mixture is dispersed into deionized water placed in a syringe. After adding acetonitrile to break up the cloudy state, the collected organic phase is injected into gas chromatography-mass spectrometry. Under optimal conditions, limits of detection and quantification in the ranges of 2.6-8.4 and 9.7-29 ng/kg, respectively, were obtained. The extraction recoveries and enrichment factors in the ranges of 70-89% and 350-445 were obtained, respectively.

Torbati M ，Farajzadeh MA ，Mogaddam MRA ，Torbati M ... -  《-》

In situ decomposition of deep eutectic solvent as a novel approach in liquid-liquid microextraction.

In this study, a novel approach for effective liquid-liquid microextraction based on deep eutectic solvent (DES) decomposition was suggested for the first time. It was established that DESs synthesized from tetrabutylammonium bromide and long-chain alcohols decomposed in aqueous phase resulting in in situ dispersion of organic phase and extraction of hydrophobic analyte(s). It this process long-chain alcohol acted as an extraction solvent and tetrabutylammonium bromide acted as a dispersive agent and promoted mass transfer between aqueous and organic phases as a salting out agent. Phenomenon of DES decomposition was studied in detail and applied for separation and preconcentration in chemical analysis for the first time. The developed approach was applied for 17β-estradiol microextraction from transdermal gel samples as a proof-of-concept example. The results showed that the in situ dispersed organic phase obtained can provide efficient extraction of 17β-estradiol with good extraction recovery (95 ± 5%) and excellent reproducibility (6%). The reported approach proves to be fast, simple, and inexpensive.

Shishov A ，Chromá R ，Vakh C ，Kuchár J ，Simon A ，Andruch V ，Bulatov A ... -  《-》

In matrix formation of deep eutectic solvent used in liquid phase extraction coupled with solidification of organic droplets dispersive liquid-liquid microextraction; application in determination of some pesticides in milk samples.

In this work, a liquid-phase extraction procedure and dispersive liquid-liquid microextraction method based on deep eutectic solvents were combined and used for the simultaneous extraction of different classes of pesticides; including carbaryl, hexythiazox, pretilachlor, iprodione, famoxadone, sethoxydim and fenazaquin from milk samples. In the first step, a deep eutectic solvent was synthesized in milk sample and simultaneously, was used for extraction of the analytes along with precipitation of milk proteins. To assist the formation of the deep eutectic solvent and increasing the mass transfer rate of the analytes, ultrasonic irradiations was used. In the second step, the collected organic phase from pervious step was mixed (as dispersive solvent) with a water-immiscible deep eutectic solvent (ChCl: decanoic acid) and injected into deionized water. The cloudy solution was placed into an ice bath and the extraction solvent was solidified on the top of the solution. After removing the solid phase by a spatula, it was melted at room temperature and 1 μL of the extraction solvent was injected into the separation system. Under the optimum extraction conditions, low limits of detection and quantification within the ranges of 0.90-3.9 and 3.1-13 ng mL-1 were achieved, respectively. Precision of the method expressed as relative standard deviation was in the ranges of 3.8-5.3 and 4.8-6.9 for intra- and inter-day (n = 5) precision, respectively, at a concentration of 50 ng mL-1 of each analyte. Extraction recoveries and enrichment factors were between 64 and 89% and 320 and 445, respectively. Lastly, several milk samples were successfully analyzed using the proposed method.

Jouyban A ，Farajzadeh MA ，Afshar Mogaddam MR 《-》