Emulsification Liquid-liquid Microextraction Research Articles

Emulsification liquid-liquid microextraction coupled with droplet digital image colorimetric detection for determination of rhodamine B in food and beverage samples

An analytical method combining fatty acid-emulsification liquid-liquid microextraction (FA-ELLME) with solidification of floating drops (SFD) and droplet digital image colorimetry (DDIC) was developed for the analysis of rhodamine B (RhB) in food and beverage samples. This work applied an emulsified amphiphilic fatty acid as an extracting solvent and a freezing procedure for extracting phase separation. A 7 mL sample volume adjusted to pH 5 was extracted with a drop of 35 μL of octanoic acid (0.5%v/v). The emulsification was initiated by shaking for 10 s followed by centrifugation for 5 min. The floating drops containing RhB were solidified in an ice bath, separated from the solution, defrosted, and dropped on the paper platform for DDIC analysis. The limit of detection (LOD) and limit of quantification (LOQ) were 1.8 μg L−1 and 6.0 μg L−1, respectively. The linear range was 10 - 40 μg L−1 (R2 = 0.997). The method was applied to determine RhB in beverage, candy, jelly, and chili sauce samples. The relative recovery percentages (RR%) between 73% and 113% were achieved.

Deep Eutectic Solvent-based green extraction and gas chromatography determination of phthalates released from food contact materials

A sensitive and efficient green emulsification liquid-liquid microextraction (ELLME) method using deep eutectic solvents (DES) for extraction of phthalates released from food contact materials (FCMs) was optimized for GC-MS determination of Butyl Benzyl Phthalate (BBP) and Di-2-Ethylhexyl Phthalate (DEHP). The optimal DES system for phthalate extraction was determined to be Choline Chloride:Phenol (1:2 molar ratio). Tetrahydrofuran (THF) was utilized as the emulsifier solvent. The effects of vortex agitation times and centrifugation times on extraction efficiency were investigated. The method yielded quantification limits (LOQ) of 0.036 and 0.005 mgL-1 for BBP and DEHP, respectively. Repeatability relative standard deviations (RSDr) of 2.9% and 2.2% were obtained for BBP and DEHP, respectively, while corresponding medium precision relative standard deviations (RSDR) were 2.8% and 3.2%. Recovery rates from spiked samples were 94.8% for BBP and 95.1% for DEHP. Finally, determination of BBP and DEHP released from contact materials into water and beverage samples at various temperatures confirmed the applicability of the method for assessment of phthalates and their migration from FCMs.

Evaluation of green silicone surfactant-based vortex assisted dispersive liquid-liquid microextraction for sample preparation of organophosphorus pesticide residues in honey and fruit sample.

A vortex-assisted surfactant enhanced emulsification liquid-liquid microextraction based on non-ionic silicone surfactant was successfully developed for the determination of organophosphorus pesticides in food samples coupled to gas chromatography-mass spectrometry. A new type of non-ionic silicone surfactant composed of polysiloxane chains was employed as a green emulsifier to facilitate the emulsification of extraction solvent into the sample matrix, thereby intensifying the mass transfer of target analytes into the organic phase. The variables that affect the extraction were systematically optimized: 80 μl of hexane and 0.5% (v/v) of silicone surfactant were used as extraction solvent and surfactant respectively, the solution was mixed well under vortex agitation for 1 min with the addition of 4% (w/v) sodium sulfate. Under optimum conditions, the linearity of the method was obtained in the range of 0.1-200 μg/kg with a good coefficient of determination varying from 0.9986 to 0.9996. The limit of detection and the limit of quantitation were between 0.008-0.1 and 0.02-0.3 μg/kg, respectively. Application of the proposed method to real samples gave satisfactory recovery values (80%-118%) for the target analytes. The suggested approach has also proven to be convenient, expeditious, and environmentally benign.

Analysis of herbicide mixtures in environmental samples with emulsification liquid-liquid microextraction using fatty acids deep eutectic solvents

ABSTRACT A method was developed for the simultaneous extraction of herbicides such as 2,4 D, MCPA, ametryn, chlorothalonil, and bromacil in water and vegetable samples by emulsification liquid-liquid microextraction with fatty acids based hydrophobic deep eutectic solvents (DES). The DES were synthesised by mixing several fatty acids ratios that functioned as both the hydrogen bond acceptor (HBA) and hydrogen bond donor (HBD). Using the DES as the microextraction solvent, several vital parameters were optimised, including the type and volume of hydrophobic DES, pH of the sample, sonication time, and type and volume of emulsifier. Then, the extracted herbicides were back-extracted into phosphoric acid solution (0.05 M). The detection limits were in the range of 0.01–2.5 ng mL−1, the quantification limits were in the range of 0.03–8.3 ng mL−1, and recoveries were in the range of 73.1–98.8% with RSD <10%. The greenness assessment using Analytical Eco-Scale and AGREE (Analytical GREEnness Metric Approach System) exhibited that the emulsification liquid-liquid microextraction method using DES can be considered as simple, practical, and environmentally friendly.

Deep eutectic solvent-based emulsification liquid-liquid microextraction for the analysis of phenoxy acid herbicides in paddy field water samples.

An emulsification liquid–liquid microextraction (ELLME) method was successfully developed using phenolic-based deep eutectic solvent (DES) as an extraction solvent for the determination of phenoxy acid herbicides, 3,6-dichloro-2-methoxybenzoic acid (dicamba) and 2-methyl-4-chlorophenoxyacetic acid (MCPA) in environmental water samples. Five different phenolics-based DESs were successfully synthesized by using phenol (DES 1), 2-chlorophenol (DES 2), 3-chlorophenol (DES 3), 4-chlorophenol (DES 4) and 3,4-dichlorophenol (DES 6) as the hydrogen-bond donor (HBD) and choline chloride as the hydrogen-bond acceptor (HBA). The DESs were mixed at 1 : 2 ratio. A homogeneous solution (clear solution) was observed upon the completion of successful synthesis. The synthesized DESs were characterized by using Fourier transform infrared and nuclear magnetic resonance (NMR). Under optimum ELLME conditions (50 µl of DES 2 as extraction solvent; 100 µl of THF as emulsifier solvent; pH 2; extraction time 5 min), enrichment factor obtained for dicamba and MCPA were 43.1 and 59.7, respectively. The limit of detection and limit of quantification obtained for dicamba were 1.66 and 5.03 µg l−1, respectively, meanwhile for MCPA were 1.69 and 5.12 µg l−1, respectively. The developed ELLME-DES method was applied on paddy field water samples, with extraction recoveries in the range of 79–91% for dicamba and 82–96% for MCPA.

Deep eutectic solvent-based clean-up/vortex-assisted emulsification liquid-liquid microextraction: Application for multi-residue analysis of 16 pesticides in olive oils

A new hydrophobic deep eutectic solvent (DES) composed of thymol and vanillin (1:1) was prepared and used as the extraction solvent in vortex-assisted emulsification liquid-liquid microextraction of 16 pesticides in olive oil before GC-μECD analysis. Due to the complexity of oil samples, a DES-based liquid-liquid solvent system (n-hexane/acetonitrile/DES) was developed to achieve an effective clean-up. Among the four examined hydrophilic DESs, [choline chloride]:[urea] led to improved sensitivity, and clean chromatograms with low noise and drift from the sample matrix. Besides, the effect of the significant factors such as extraction solvent volume, pH, ionic strength, and vortex time was investigated. At the optimized conditions, the validation parameters such as linear range 0.04–250 μg kg−1, the limits of detection of 0.01–0.08 μg kg−1, intra-day, and inter-day relative standard deviations (RSDs) < 6.8 and < 9.7%, were obtained. This method was followed by GC-μECD and applied to determine pesticides in five olive oil samples. The relative recoveries were in the range of 63.1–119.4%.

Towards green analysis of curcumin from tea, honey and spices: Extraction by deep eutectic solvent assisted emulsification liquid-liquid microextraction method based on response surface design

ABSTRACT A fast, cheap and green analytical method was developed for the determination and extraction of curcumin in tea, honey, and spices using deep eutectic solvent-assisted emulsification liquid–liquid micro-extraction (DES-ELLME) coupled to UV-VIS spectrophotometry. Quantitative extraction of curcumin from the sample was obtained by the DES, which was prepared by mixing choline chloride and maltose in a 1:3 molar ratio. Response surface design was used for the optimisation of significant experimental parameters including sample pH, amount of extraction solvent, amount of emulsifier solvent and vortex time. The optimum conditions obtained were pH 4.25, 762.5 μL of DES, 107.5 mL of tetrahydrofuran and 3.4 min vortex time, while keeping centrifugation speed fixed at 4000 rpm, 5 min. Under the extraction conditions obtained, analytical features such as calibration equation, limit of detection, enrichment factor, and linearity were Abs = 6.5 × 10−4 [Curcumin, ng mL−1]-1.2 × 10−5, 0.1 ng mL−1, 114 and 0.4–120 ng mL−1, respectively. Moreover, the repeatability and reproducibility of the DES-ELLME method, expressed as relative standard deviation (RSDs%), varied in the ranges of 1.4–3.0% and 2.0–4.3%, respectively. Finally, the proposed method was successfully applied to the extraction and determination of curcumin from prepared samples. The relative mean recovery ranged from 92.3% to 104.4%.

Use of Deep Eutectic Solvent-based Air-assisted Emulsification Liquid-liquid Microextraction of Palladium and Determination by Flame Atomic Absorption Spectrometry in Water and Environmental Samples

Use of Deep Eutectic Solvent-based Air-assisted Emulsification Liquid-liquid Microextraction of Palladium and Determination by Flame Atomic Absorption Spectrometry in Water and Environmental Samples

Characterization of key odorants causing the roasted and mud-like aromas in strong-aroma types of base Baijiu.

The roasted and mud-like aromas in Chinese strong-aroma types of base Baijiu (base SAB) and the interactions among the corresponding key compounds causing these two characteristic aromas were investigated. A total of 68 and 64 odorants were identified in the base and commercial SAB by comparative aroma extract dilution analysis. Furthermore, the complex matrix of Baijiu always pose a long-term challenge for quantitative accuracy and precision of target aroma compounds; thus, the odorants with flavor dilution (FD) ≥ 9 were further quantified by multiple quantitative techniques, including the direct injection combined with gas chromatography-flame ionization detector, the vortex-assisted surfactant-enhanced emulsification liquid-liquid microextraction (VSLLME) combined with GC-MS, and the derivatization method combined with VSLLME-GC-MS, and 37 and 26 odorants were shown to be important odorants as their OAVs ≥1. Among these components, 5 compounds, hexanoic acid, butyric acid, p-cresol, 3-methylindole, and 3-(methylthio)propanal showed higher OAVs in base than in commercial SAB, and based on aroma recombination and omission analysis, they were confirmed to be the key odorants responsible for the mud-like and roasted odors. The evaluation of the aforementioned five key odorants by the "addition" test showed that the roasted and mud-like aromas of base SAB were related, and the odors were mainly attributed to additive or masking effects among the compounds.

Deep Eutectic Solvent Based Air Assisted Ligandless Emulsification Liquid-Liquid Microextraction for Preconcentration of Some Heavy Metals in Biological and Environmental Samples.

In this study, a deep eutectic solvent (DES) based on air-assisted ligandless emulsification liquid-liquid microextraction method (DES-AA-LL-ELLME) was considered for preconcentration and extraction of some metals (Cd, Ni, Pb and Cu). A 1:1 mixture of the synthesized DES and triethylamine was added as an extractant to extract metal ions in the absence of chelating agent. Tetrahydrofuran as the aprotic solvent provided a turbid state. To disperse the aggregated DES droplets into the aqueous phase, air-assisted was performed. The influence of several effective parameters was monitored. Under optimum conditions, limits of detection were found in the range of 0.31-0.99µgL-1 with preconcentration factor from 67 to 69. The relative standard deviation (n = 10) was in the range of 2.1%-3.1% for all analytes. This procedure was applied to determine some metals in both biological and environmental samples with appropriate recoveries about 98.7%-106%.

Vortex assisted deep eutectic solvent (DES)-emulsification liquid-liquid microextraction of trace curcumin in food and herbal tea samples

We developed a new microextraction method for separation and preconcentration of curcumin using deep eutectic solvent known as green solvent. Deep eutectic solvent (DES) formed by mixing of choline chloride and phenol was used as an extraction solvent in microextraction study to extract the curcumin at pH 4.0. The curcumin concentration in enriched DES phase was analyzed by UV–Visible spectrophotometer. The effect of parameters such as pH, mol ratio of DES composition, volume of DES, volume of tetrahydrofuran (THF) and sample volume were examined. Interference effects of matrix components were investigated. The preconcentration factor was 12.5. The detection limit of method (n = 10) was 2.86 µg L−1 and the relative standard deviation (RSD, n = 8) was 1.8%. The method was successfully applied to determination of curcumin in food and herbal tea samples. The mean recoveries were between 96% and 102% and standard deviations were found in the range of 1–6%.

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%.

Determination of Lead in Water Samples Using a New Vortex-Assisted, Surfactant-Enhanced Emulsification Liquid-Liquid Microextraction Combined with Graphite Furnace Atomic Absorption Spectrometry.

A low toxic solvent-based vortex-assisted surfactant-enhanced emulsification liquid-liquid microextraction (LT-VSLLME) combined with graphite furnace atomic absorption spectrometry was developed for the extraction and determination of lead (Pb) in water samples. In the LT-VSLLME method, the extraction solvent was dispersed into the aqueous samples by the assistance of vortex agitator. Meanwhile, the addition of a surfactant, which acted as an emulsifier, could enhance the speed of the mass-transfer from aqueous samples to the extraction solvent. The influences of analytical parameters, including extraction solvent type and its volume, surfactant type and its volume, pH, concentration of chelating agent, salt effect and extraction time were investigated. Under the optimized conditions, a good relative standard deviation of 3.69% at 10 ng L(-1) was obtained. The calibration graph showed a linear pattern in the ranges of 5-30 ngL(-1), with a limit of detection of 0.76 ng L(-1). The linearity was obtained by five points in the concentration range of 5-30 ngL(-1). The enrichment factor was 320. The procedure was applied to wastewater and river water, and the accuracy was assessed through the analysis of the recovery experiments.

Low‐density solvent‐based vortex‐assisted surfactant‐enhanced emulsification liquid–liquid microextraction and its application

For the first time, the low-density solvent-based vortex-assisted surfactant-enhanced emulsification liquid-liquid microextraction, followed by GC-flame photometric detection has been developed for the determination of eight organophosphorus pesticides in aqueous samples. A small volume of organic extraction solvent (toluene) was dispersed into the aqueous samples by the assistance of surfactant and vortex agitator. The extraction was performed in a special disposable polyethylene pipette, allowing using the reagents with lower density than water as extraction solvents. The influence parameters were systemically investigated and optimized: toluene (30 μL) and Triton X-100 (0.2 mmol/L) were used as the extraction solvent and the surfactant, respectively, and the extraction was performed for 1 min under room temperature without adding sodium chloride. Under the optimum conditions, the validation parameters such as the RSD (n = 6; 2.1-11.3%), LOD (0.005 and 0.05 μg/L), and linear range (0.1-50.0 μg/L with correlation coefficients (0.9958-0.9992) showed the method was satisfying. The proposed method has been successfully applied to the determination of the organophosphorus pesticides in real samples with recoveries between 82.8 and 100.2%.

Ultrasound-assisted emulsification microextraction coupled with gas chromatography–mass spectrometry using the Taguchi design method for bisphenol migration studies from thermal printer paper, toys and baby utensils

The optimization of a clean procedure based on ultrasound-assisted emulsification liquid-liquid microextraction for the sensitive determination of four bisphenols is presented. The miniaturized technique was coupled with gas chromatography-mass spectrometry after derivatization by in situ acetylation. The Taguchi experimental method, an orthogonal array design, was applied to find the optimal combination of seven factors (each factor at three levels) influencing the emulsification, extraction and collection efficiency, namely acetic anhydride volume, sodium phosphate concentration, carbon tetrachloride volume, aqueous sample volume, sodium chloride concentration and ultrasound power and application time. A second factorial design was applied with four factors and five levels for each factor, 25 experiments being performed in this instance. The matrix effect was evaluated, and it was concluded that sample quantification can be done by calibration with aqueous standards. The detection limits ranged from 0.01 to 0.03 ng mL(-1) depending on the compound. The environmentally friendly sample pretreatment procedure was applied to study the migration of the bisphenols from different types of samples: thermal printer paper, compact discs, digital versatile discs, small tight-fitting waistcoats, baby's bottles, baby bottle nipples of different materials and children's toys.