Switchable Hydrophilicity Solvent Research Articles

Development of a vortex-assisted switchable-hydrophilicity solvent-based liquid phase microextraction for fast and reliable extraction of Zn (II), Fe (II), Pb (II), and Cd (II) from various baby food products

This manuscript describes the development of a novel liquid phase microextraction (LPME) method for the extraction and determination of Zn (II), Fe (II), Pb (II), and Cd (II) in various infant/baby food and supplements products. The method is based on vortex-assisted extraction combined with a switchable-hydrophilicity solvent (SHS) sample preparation. The SHS, which undergoes reversible phase changes triggered by pH change, enables selective extraction and easy phase separation. A flame atomic absorption spectroscopy was used in the final determination step. Optimization studies revealed, that the optimal pH of the sample solution (after digestion) during analytes extraction is 5.5. A l-proline is added to the sample (375 mM) to ensure the complexation of the target metal cations. After the complexation step, 750 µL of SHS - a N, N-Dimethylcyclohexylamine along with 0.9 mL of 2 M of acetic acid solution is added (hydrophilicity switch-on stage) and mixed manually to obtain a homogeneous solution. In the last stage, 0.45 mL of 10 M NaOH solution (hydrophilicity switch-off stage) is added to the sample solution and a vortex for 100 s is applied to ensure the effective extraction and separation of the complex containing the analytes. At this stage, a cloudy solution is immediately obtained. Finally, the effective phase separation is obtained at the centrifugation step (4000 rpm for 2 mins). The method limit of detection was as 0.03, 0.009, 0.6, and 0.2 ng/L for Zn (II), Fe (II), Cd (II), and Pb (II) respectively with RSD% below 2.0 %. The analysis of certified reference materials and real samples proved the full applicability of the method for routine analysis, contributing to the field of heavy metal analysis and ensuring the safety of baby products. According to the AGREE methodology, this method can be named as green analytical chemistry method with a score of 0.77.

Switchable hydrophilicity solvent-assisted solidified floating organic drop microextraction for separation and determination of arsenic in water and fish samples

The aim of the current study was to separate and determine arsenic in water and fish samples using a novel and green solidified floating organic drop microextraction (SFODME), which is based on switchable hydrophilicity solvent (SHS)-assisted procedure followed by hydride generation atomic absorption spectrometry (HG-AAS). The 4-((2-hydroxyquinoline-7-yl)diazenyl)-N-(4-methylisoxazol-3-yl)benzene sulfonamide (HDNMBA) and tertiary amine (4-(2-aminoethyl)-N,N-dimethylbenzylamine (AADMBA) were used as ligand and SHS, respectively. The use of SHS promotes quantitative extraction of arsenic complexes into an extraction solvent (1-undecanol). Some factors that impact extraction recovery were studied. Under optimal conditions, the limit of detection (LOD) and limit of quantification (LOQ) were 0.005 μg L−1 and 0.015 μg L−1, respectively. The calibration graph was linear up to 900.0 μg L−1 arsenic, with the enrichment factor is 267. The proposed SHS-SFODME methodology for arsenic quantification in water and fish samples was successfully implemented. The environmental friendliness and safety of proposed method were approved by the Analytical Greenness Calculator (AGREE) and the Blue Applicability Grade Index (BAGI) tools.

Salicylic acid as a switchable hydrophilicity solvent for the microextraction of the antibiotic amphotericin B from human urine followed by HPLC-UV analysis

Monitoring the concentration levels of amphotericin B in the human organism is of utmost importance to evaluate the efficacy of the therapy. However, the reported sample preparation protocols for the extraction of this compound are very limited. In this work, salicylic acid is utilized as a switchable hydrophilicity solvent for the microextraction of amphotericin B from human urine samples before the HPLC analysis. The method is based on the phase transition of salicylic acid by changing the pH of the sample enabling efficient dispersion and phase separation in one step. A high contact area of the solidified solvent with the sample solution provided effective extraction of the target analyte. Among others, critical experimental parameters affecting the extraction performance of the drug were systematically investigated. The separation of the drug was carried out on a C8 stationary phase using mixtures of citric acid and methanol as mobile phases. Excellent linearity was observed in the range of 0.1 – 2.0 μg mL−1, while the precision (%RSD) was less than 14.5 % in all cases. The lower limit of quantification was 0.1 μg mL−1, and the limit of detection was 0.03 μg mL−1. The intra-day and inter-day accuracy were satisfactory, being in the range of 85.2 – 109.1 %. The robustness of the microextraction protocol was evaluated using DoE. The green potential and the practicality of the proposed analytical scheme were examined based on Green Analytical Procedure Index (GAPI) and Blue Applicability Grade Index (BAGI), respectively. A BAGI score of 65 was attained, demonstrating good applicability in terms of practicality, while the novel protocol was found to show green merits. The developed method can be used for the analysis of the drug in human urine.

Switchable-hydrophilicity solvent-based liquid phase microextraction for determination of brilliant green in water, shellfish, and fish samples

To avoid substances harmful to the environment and humans, reducing residues generated during chemical tests and substituting solvents has attracted much interest from the scientific community. This study introduces an innovative approach, harnessing switchable-hydrophilicity solvent-based liquid phase microextraction to determine brilliant green. The microextraction process is based on the dispersion of a switchable-hydrophilicity solvent (octanoic acid) for the preconcentration of brilliant green. The alternation between these two forms, hydrophobic (immiscible) and hydrophilic (miscible), can be obtained by changing the composition of the solution, where sodium bicarbonate and sulfuric acid were employed. Factors such as pH, sample volume, switchable solvent volume, and acid-base ratio were optimized to obtain the best analytical response for brilliant green preconcentration. The detection limit was 1.4 μg/L, and the enrichment factor was 250. This novel method successfully assessed brilliant green levels in water, shellfish, and fish samples. It emerges as an accessible, cost-effective, and eco-conscious alternative for quantifying brilliant green, aligning seamlessly with the mission to protect the environment and human health.

Toxicity evaluation of coconut oil extracted with switchable hydrophilicity solvent (SHS) as a potential solvent contamination indicator

Toxicity evaluation of coconut oil extracted with switchable hydrophilicity solvent (SHS) as a potential solvent contamination indicator

A new ultrasound-assisted liquid-liquid microextraction method utilizing a switchable hydrophilicity solvent for spectrophotometric determination of nitrite in food samples

A new ultrasound-assisted liquid-liquid microextraction method utilizing a switchable hydrophilicity solvent for spectrophotometric determination of nitrite in food samples

Edible oil-based switchable-hydrophilicity solvent liquid–liquid microextraction for the determination of lead in food samples using flame-atomic absorption spectrometry

Edible oil-based switchable-hydrophilicity solvent liquid–liquid microextraction (EO-SHS-LLME) was used prior to the determination of lead as its metal chelate with ammonium pyrrolidine dithiocarbamate (APDC) by flame-atomic absorption spectrometry. Optimum extraction conditions were achieved using 600 µL of coconut oil as the extraction solvent, pH of sample solution adjusted to 4.50 and containing 1.0% (w/v) APDC, within 5.0 min complexation time, a 300 µL of 2.0 M sulfuric acid as the hydrophilicity switching-off trigger, and 150 µL of 8.0 M nitric acid as the back-extraction solution within 4.0 min back-extraction time. The limits of detection and quantification were found as 2.8 and 9.4 µg g−1, respectively. Good linearity was obtained with coefficients of determination (R2) higher than 0.9961. Intraday and interday precision, expressed in terms of relative standard deviation, were less than 4.0% and 4.6%, respectively, while the linear dynamic range was from 12.6 to 175.0 µg g−1. Accuracy was checked by addition-recovery tests and percentage recoveries were found to be within the range of 97.1–106.0%. The proposed method was applied for the determination of lead in food samples (i.e., carrot, fish, onion, potato and yam) and satisfactory results were achieved.

Switchable-Hydrophilicity Solvent Liquid-Liquid Microextraction Prior to Spectrophotometric Determination of Sudan I Dye in Spices

Sudan I was determined using a switchable-hydrophilicity solvent (SHS) followed by ultraviolet/visible spectrophotometric detection at 445.0 nm in a simple, fast, sensitive, and low-cost method. The optimum switchable-hydrophilicity solvent liquid-liquid microextraction (SHS-LLME) conditions were achieved with 600 µL of octylamine and 600 µL of 10.0 M sodium hydroxide in 20.0 mL of the sample. Limits of detection ranged from 0.009 to 0.021 µg mL−1. The coefficients of determination (R2) of the calibration graphs were higher than 0.9983 and relative standard deviations were below 8.6%. Enrichment factors ranged between 5.29 and 12.89. The proposed method was applied to spices with recoveries (%RR) between 92.5% and 104.4%.

Switchable hydrophilicity solvent based microextraction of mercury from water, fish and hair samples before its spectrophotometric detection

Mercury is highly toxic even at trace levels and causes severe health problems in human beings. Therefore, proper extraction, preconcentration and quantification of Hg2+ in different samples are highly important. The present work is based on the preconcentration of Hg2+ in water, hair and fish samples using switchable hydrophilicity solvent-based liquid-liquid microextraction (SHS-LLME) before its quantification by UV–visible spectrophotometry. 2-(5-Bromo-2-pyridylzo-5-(diethylamino)phenol) (5-Br-PADAP) was used to form colored complex with Hg2+. Optimization studies show that at pH 8 maximum % recovery of the Hg2+ was obtained with 400 μL of extraction solvent. The amount of 5-Br-PADAP (20 μg) was enough for the complete derivatization of Hg2+ to Hg2+-5-Br-PADAP. The maximum volume of the sample was optimized as 20 mL up to which the analyte can be quantitatively extracted. Figures of merits like detection and quantification limits (n = 7) were calculated as 0.014 ng mL−1 and 0.048 ng mL−1, respectively. The relative standard deviation was determined as 5.6 for (n = 7) repeated determinations. Preconcentration and enhancement factors originated as 50 and 48, respectively. Validation was done using certified reference materials like TMDA 53.3 water and NCS ZC81002B human hair and water, hair and fish samples.

Dissolution dynamics of a binary switchable hydrophilicity solvent-polymer drop into an acidic aqueous phase.

Switchable hydrophilicity solvents (SHSs) are solvents defined by their ability to switch from their hydrophobic form to a hydrophilic form when brought into contact with an acidic trigger such as CO2. As a consequence, SHSs qualify as promising alternatives to volatile organic compounds during industrial solvent extraction processes, as greener and inexpensive methods can be applied to separate and recover SHSs. Furthermore, because of their less volatile nature, SHSs are less flammable and so increase the safety of a larger scale extraction process. In this work, we study the dynamics and in-drop phase separation during the dissolution process of a drop composed of a SHS and a polymer, triggered by an acid in the surrounding aqueous environment. From 70 different experimental conditions, we found a scaling relationship between the drop dissolution time and the initial volume with an overall scaling coefficient of ∼0.53. We quantitatively assessed and found a shorter dissolution time related to a decrease in the pH of the aqueous phase or an increase in the initial polymer concentration in the drop. Examining the internal state of the drop during the dissolution revealed an in-drop phase separation behavior, resulting in a porous morphology of the final polymer particle. Our experimental results provide a microscopic view of the SHS dissolution process from droplets, and findings may help design SHS extraction processes for particle formation from emulsions.

An innovative simplified one-pot process for Astaxanthin purification from Paracoccus carotinifaciens

Astaxanthin (ASX) is a carotenoid with several applications in the food and pharmaceutical fields which is recognised as having a higher physiological and commercial value when it is biologically rather than chemically sourced. This work experimentally investigates the bio-fractionation of biomass of the Paracoccus carotinifaciens bacterium by extraction with the switchable hydrophilicity solvent N,N-dimethyl cyclohexylamine (DMCHA) to obtain ASX and related carotenoids in separate form. This is done by means of a sequential process carried out in a single apparatus. DMCHA gave an extraction yield in terms of equivalent ASX extracted per unit mass of processed dry microbial biomass (62.5 %) higher than acetone (48 %) and ethanol (14 %). After the DMCHA was washed from the extract with carbonated water, 88.2 % of the extracted ASX was recovered. The possibility of extracting carotenoids with recycled solvent with a minor (-7.7%) efficiency drop was also demonstrated, as was the lower energy footprint of DMCHA-based than competing volatile solvent-based extraction processes.

Volumetric and transport properties of switchable-hydrophilicity solvent systems: N,N-Dimethylbutylamine, water and carbon dioxide

Switchable-hydrophilicity solvents (SHSs) are an emerging class of solvents with switchable phase behavior. They can be used as a substitute for volatile solvents and can be removed from organic products without distillation. However, the detailed physical properties data of SHSs are still very scarce in the literature. In this work, the experimental values densities, dynamic viscosities, refractive indices as well as conductivities of switchable hydrophilicity solvent (SHS)systems (N,N-Dimethylbutylamine (DMBA), water, and carbon dioxide) are investigated at temperatures (283.15, 288.15, 293.15, 298.15, 303.15 and 308.15) K and at atmospheric pressure. VLE of the CO2 loaded DMBA solutions are measured at 298.15 K over the partial pressure range of carbon dioxide from 17.0 to 98.0 kPa. Density data have been used to calculate the apparent molar volumes (Vϕ), limiting apparent molar volumes (Vϕ0) and limiting partial molar expansivity of solute (Eϕ0). The Jones-Dole coefficients B, the Gibbs free energies of activation of viscous flow per mole of solvent (Δμ10≠) and per mole of solute (Δμ20≠), entropies (ΔS20≠) and enthalpies (ΔH20≠) of activation of viscous flow were calculated from experimental viscosity data and discussed in terms of transition state theory. The Walden's product was calculated from the conductance and dynamic viscosity data. The results are valuable sources of information on the design and development of SHSs for novel industrial applications.

Dispersive Liquid‐Liquid Microextraction (DLLME) Based on Solidification of Switchable Hydrophilicity Solvent Coupled with High‐Performance Liquid Chromatography (HPLC) with Photodiode Array (PDA) Detection for the Determination of Pyrethroid Pesticides in Grains

Rapid dispersive liquid-liquid microextraction (DLLME) based on the solidification of a switchable hydrophilicity solvent (SHS) was established for the preconcentration of pyrethroid pesticides from grain prior to determination using high‐performance liquid chromatography (HPLC) with photodiode array (PDA). Lauric acid was selected to be the switchable hydrophilicity solvent due to its conversion between hydrophobic and hydrophilic forms and solidification at low temperature, thereby avoiding a time-consuming centrifugation step. The results show that the optimal conditions for pyrethroid pesticides included 30 mmol/L lauric acid, hydrochloric acid as the hydrogen donor, a 1:1.8 stoichiometric ratio of sodium laurate and hydrochloric acid, an extraction temperature of 50 °C, an extraction time of 8 min, and a solidification time of 3 min. Under the optimal conditions, this approach provided a high enrichment factor (308.4 to 330.2), a short pretreatment period of less than 15 min, and sensitive detection limits from 5 to 20 ng/g suitable for the analysis of food. The method was employed for the determination of pyrethroid pesticides in grain. The recoveries were 84.3% to 115.7%, and the relative standard deviation was less than 9.9%.

Switchable-hydrophilicity solvent liquid-liquid microextraction combined with smartphone digital image colorimetry for the determination of palladium in catalytic converters.

Switchable-hydrophilicity solvent liquid-liquid microextractionwas coupled with smartphone digital image colorimetry for the determination of palladium as its metal chelate with N,N-diethyl-N'-benzoylthiourea. Images of the colored extract were captured in a homemade colorimetric box, which were split into their red-green-blue channels. The blue channel was used to determine the concentration of palladium. Optimum extraction conditions were achieved using 600 μL of triethylamine as the extraction solvent and 4.0mL of 10M sodium hydroxide as the hydrophilicity-switching trigger within 1.0min extraction time. Optimum complexation conditions were obtained at a sample pH of 4.50, andmetal/ligand mole ratio of 1:2 within 3.0min. Optimum detection conditions were achieved at a distance of 7.0cm between the sample solution and the detection camera, a region of interest of 175.0 px2 at a detection wavelength of 480.0nm and 30.0% brightness of the monochromatic light source. Limits of detection and quantitation were found to be less than 0.7 and 1.8µgg-1, respectively. A good linearity with coefficients of determination above 0.9974 was obtained. Accuracy was checked via a single-factor analysis of variance (ANOVA) test by comparing the results with the ones obtained using flame-atomic absorption spectrometry and the results were statistically in a good agreement (P > 0.05). The proposed method was applied for the determination of palladium in catalytic converters with percentage relative recoveries ranging between 95.7 and 103.7% and percentage relative standard deviations below 4.0%.

CO2-triggered switchable hydrophilicity solvent as a recyclable extractant for ultrasonic-assisted extraction of Polygonatum sibiricum polysaccharides

In this study, CO2-triggered switchable hydrophilicity solvents (SHSs) based on different amines and water were employed in the ultrasonic-assisted extraction of Polygonatum sibiricum polysaccharides (PSPs). When CO2 was pumped into the amine, the solution became hydrophilic and could be used as an extractant for PSPs extraction. When CO2 was removed, the solution switched hydrophobicity, with the extractants being separated from the extract and further recycled and reused. The factors affecting the solid–liquid extraction of PSPs were studied. The maximum extraction yield of 399.2 mg/g was obtained at a solid–liquid ratio of 1:20, extraction time of 60 min, extraction temperature of 50 °C, and ultrasonic power of 500 W. SHSs could be recovered and reused with 88.4% recovery after the fifth cycle. The molecular weights and monosaccharide compositions of PSPs were also determined. This study provides a new strategy for sustainable extraction of plant polysaccharides and other bioactive ingredients.

Preconcentration of triazole fungicides using effervescent assisted switchable hydrophilicity solvent-based microextraction prior to high-performance liquid chromatographic analysis

An effective preconcentration method namely, effervescent assisted switchable hydrophilicity solvent-based microextraction with the solidification of floating organic droplet, was investigated for enrichment of triazole fungicides prior to their analysis by HPLC. In this work, octanoic acid (as extraction solvent) was generated by in-situ formation between sodium octanoate and citric acid. Carbon dioxide was occurred during the process, which induced the mass transfer and improve the extraction efficiency of the target analytes. The switchable hydrophilicity solvent was collected after solidification in an ice-bath. The experimental parameters were investigated and optimized. Good linearity was obtained over the range of 3–100 μg L-1, with a coefficient of determination more than 0.99. Low limits of detection (1 μg L-1), and acceptable enrichment factors (29.13–102.39) were obtained. The relative standard deviation (RSD) of intra-day (n = 5) and inter-day (n = 5 × 3 days) for the studied triazoles at a concentration level of 10 μg L-1 were less than 3.10 %. Eventually, the presented extraction method was prosperously investigated to the analysis of trace levels of triazole fungicides in water and honey matrices. The results show that no residue of the studied triazoles was observed in the studies samples.

Development of a new green microextraction technique, switchable hydrophilicity solvent-based homogenous liquid–liquid microextraction, to analyze synthetic cannabinoids in plasma

Synthetic cannabinoid receptor agonists (SCRA) are currently the most popular class of new psychoactive substances (NPS) in several countries, including Brazil. Notwithstanding that, they pose a threat to public health, as little of their toxicological properties is known. Moreover, these SCRAs have different presentations compared to classic cannabinoids and are not usually detected by conventional analytical methods due to their chemical variety. Thus, the development of new methodologies fit to analyze SCRAs is extremely warranted. In that regard, the use of environmentally benign or green approaches has been a trend in the last decades and has gained attention in Forensic Toxicology – so much so that guidelines have been established for that purpose, e.g. green analytical toxicology (GAT). With that in mind, the aim of this work was to develop and validate a quantitative method to analyze SCRAs in plasma by a novel green technique that agrees with the principles of GAT. A switchable hydrophilicity solvent-based homogenous liquid–liquid microextraction (SHS-HLLME) was developed and statistical tools were used to optimize it. Analysis of Variance (ANOVA) was chosen to find the best switchable hydrophilicity solvent (SHS) and Full Factorial and Central Composite design to study the following variables: volume of SHS:HCl 6 M mixture (200–500 μL) and NaOH 10 M (200–500 μL), salting-out effect, and time of extraction (1–5 min). The ANSI/ASB Standard 036, 1st edition 2019 guidelines were used for method validation. All analyses were performed using a UPLC-MS/MS with the multiple reaction monitoring approach. Ethical Committee approval No. 46404121.8.3001.0067. Funded by CNPq 142056/2020-0, CAPES/INSPEQT 16/2020, and FAPESP 21/09857-8. ANOVA showed that between two SHS tested, N,N-dimethylcyclohexylamine and dipropylamine, the latter yielded higher analyte recovery ( P < 0.05). Moreover, the Design of Experiment tools herein used showed that the salting-out effect and time of extraction had no major impact on analyte recovery; in contrast, 500 μL of both SHS:HCl mixture and NaOH yielded higher analyte recovery ( P < 0.05). Once optimized, the proposed technique was successfully validated according to international guidelines with the following parameters: limits of detection: 0.01–0.08 ng/mL; limit of quantitation: 0.1 ng/mL; linearity: 0.1–10 ng/mL; bias and precision < 15%; no carryover was observed and the method proved to be selective for the aimed SCRAs. The matrix effect, recovery efficiency, and process efficiency studies are being currently carried out. The microextraction technique herein developed is based on an acid-base neutralization between HCl and NaOH, making it an approach significantly more sustainable when compared to conventional choices that rely entirely on organic solvents. In that regard, only 250 μL of dipropylamine was required–an organic solvent considerably less toxic than those used in common extractions, organochlorides for example. In addition, a small volume was used compared to more conventional techniques in forensic analyses, such as solid-phase extraction (> 500 μL). Hence, we were able to successfully detect and quantitate 31 SCRAs at extremely low concentrations (0.01–0.1 ng/mL, respectively) using only 300 μL of plasma, showing that the SHS-HLLME can be used for the analysis of multiple SCRAs in a single run, thus could be a valuable tool in forensic cases. We demonstrated for the first time the application of the novel SHS-HLLME for synthetic cannabinoids. The microextraction technique herein developed has promising applications in Forensic Toxicology, as it consists of a simple and fast procedure that yields high sensitivity with only a few microliters of a biological sample. Also, it avoids the use of highly toxic chemicals and generates less residue, thus it fits the growing trend of using sustainable analytical methodologies, established by GAT and other similar guidelines.

Optimization of vortex-assisted switchable hydrophilicity solvent liquid phase microextraction for the selective extraction of vanillin in different matrices prior to spectrophotometric analysis

The main purpose of this research article is to develop a vortex-assisted switchable hydrophilicity solvent liquid phase microextraction (VA-SHS-LPME) for the selective and efficient extraction of trace vanillin in food samples. Four switchable hydrophilicity solvents (SHSs) were prepared and tested for the extraction of vanillin. The obtained extract phase after phase separation was analyzed by UV–vis spectrophotometry. The extraction parameters including pH, vortex time, NaOH volume, and SHS volume were optimized using central composite design based on response surface methodology. Under optimized conditions, the linear range (0.2–400 ng mL−1 with r2 = 0.9985), limit of detection (0.06 ng mL−1), limit of quantitation (2.0 ng mL−1), extraction recovery (97 ± 4 %) and enhancement factor (220) were obtained. Also, relative standard deviations were less than 2.1 % indicating good precision. The VA-SHS-LPME procedure showed some advantages including good extraction, low consumption of chemical and low matrix effect. Finally, the VA-SHS-LPME procedure was applied for the determination of vanillin in food samples, and acceptable recoveries (91 ± 3–99 ± 3 %) were obtained.

Optimization of a rapid and sensitive ultrasound-assisted liquid-liquid microextraction using switchable hydrophilicity solvent for extraction of β-carotene in fruit juices and vegetables

A simple, rapid and sensitive ultrasound-assisted liquid-liquid microextraction by switchable hydrophilicity solvent (UA-LLME-SHS) method was developed first time for extraction and determination of β-carotene from fruit juices and vegetables using a spectrophotometer. The effect of pH, solvent dose, ultrasound time, volume of NH4OH, volume of NaCl (w/v) and effects of different chemicals on extraction recovery was investigated. The proposed method showed good extraction recovery of β-carotene. The working range of the developed method was 50–700 ng mL−1. Limits of detection and quantification were 15.5 μg L-1 and 50 μg L-1, respectively. The intraday and interday precisions of the developed method was investigated for 75 ng mL−1 and 400 ng mL−1 of β-carotene. As a result of the study, the relative standard deviation values were in the range of 2.8–3.3 % and 3.0–4.2 % for the intraday and interday studies, respectively. The enhancement factor was 114 and extraction recovery of β-carotene was found 98.3 %. The factorial design was drawn to know the combined effects of variables and their significant and insignificant effects on the determination of the β-carotene.

Preparation of ethyl cellulose–glycerol tribenzoate microcapsules in CO2/N2‐switchable hydrophilicity solvent and solvent recycling

AbstractIn this article, a novel method of microcapsule preparation was provided, that is, ethyl cellulose–glycerol tribenzoate microcapsule (EGM) was prepared using CO2/N2 switchable hydrophilicity solvent(N, N‐dimethylcyclohexylamine) combined with an emulsion method. Microcapsules were prepared and solvents were recovered by changing the properties of the solvent. The optimum preparation conditions of EGM were the materials ratio of 20%, the oil–water ratio of 4.5:5.5, emulsifier content of 2%, the Span80‐Tween80 ratio of 1:3, and the core‐shell ratio of 1. The morphology of EGM is spherical, and the particle size can be adjusted from 0.01 μm to 90 μm by controlling the agitation speed in the synthesis process. Surprisingly, the average yield(Y[%]) reached 95.36%, the effective content(W[%]) reached 41%, and the encapsulation rate(E[%]) reached 90.66% of EGM. The solvent recovery rate(SR[%]) of the first recovered is 96.37%. Significantly, this method not only provides a new idea for the preparation of microcapsules but also expands the application field of switchable hydrophilicity solvents, which makes it has great potential application value in the field of microcapsule preparation in the future.