Eutectic Liquid Phase Research Articles

Medium/Long Chain Hydrophobic Deep Eutectic Solvent-Based Liquid Phase Microextraction for the Determination of Rhein, Emodin, and Chrysophanol with Detection by High-Performance Liquid Chromatography (HPLC)

Medium/long-chain fatty acids/alcohols as hydrogen bond donors coupled with methyltrioctylammonium chloride were used to prepare hydrophobic deep eutectic solvents (DESs) that were employed for the extraction of the anthraquinones (rhein, emodin, and chrysophanol) from fetal bovine serum. Hydrophobic DES-based liquid-phase microextraction and high-performance liquid chromatography were developed. The most suitable combination was optimized for liquid-phase microextraction. Spiked fetal bovine serum was analyzed with satisfactory extraction recoveries.

Evolution of microstructure and mechanical properties of TiB2-7.5 wt.% WC-based cermets sintered at different temperatures

The evolution of microstructure and mechanical properties of TiB2–7.5 wt% WC-based cermets sintered at different temperatures were investigated. The results showed that eutectic liquid phase appeared at around 1335 °C, indicating that solid-phase sintering occurred below that temperature, while liquid-phase sintering occurred above that temperature. TiB2, W2CoB2, WB and CoNi phases were detected in the XRD patterns of cermets sintered at different temperatures, and TEM analysis showed the presence of TiC phase. So the following chemical reaction should occur: TiB2 + WC + Co → W2CoB2 + WB + TiC. The TiB2 core - (Ti, W, Co, Ni)(B, C) rim phase were observed in the cermet sintered at 1397 °C. As the increase of sintering temperature, the solubility of WC and TiB2 in CoNi binder phase, and the number of core-rim structure hard phase particles increased. The formation of core-rim structure enhanced the interfacial bonding strength between TiB2 phase and CoNi binder, which was beneficial for improving the strength and toughness of cermets. The cermets sintered at 1465 °C had good comprehensive mechanical properties, with a relative density of 99.62%, a hardness of 17.34 ± 0.43 GPa, a transversal rupture strength of 2038 ± 53 MPa, and an indentation fracture toughness of 12.15 ± 0.32 MPa·m1/2.

Simultaneous extraction and derivatization of biogenic amines during in-situ deep eutectic solvent-based liquid phase extraction from Doogh samples prior to HPLC analysis

A simple and efficient microwave-assisted extraction method using deep eutectic solvent was developed for the simultaneous analysis of four biogenic amines (putrescine, tyramine, cadaverine and histamine) in Doogh (yogurt-based beverage) samples. Important parameters like precipitating agent volume, vortexing time, microwave power, and exposure time were optimized. Zinc sulfate was utilized for proteins precipitation prior to extraction of analytes with the deep eutectic solvent choline chloride/p-anisidine. The analytes were derivatized with dansyl chloride and analyzed by HPLC-DAD. The method showed good linearity (r2 ≥ 0.994) over wide ranges with low limits of detection (0.52–0.78 ng mL−1) and quantification (1.7–2.5 ng mL−1). Extraction recoveries ranged from 68–72 % and relative standard ≤8.1 %. Negligible matrix effects were observed. When the method was applied to real Doogh samples and several biogenic amines were detected. The developed method provided reliable results in terms of sensitivity and selectivity.

Development of liquid phase microextraction-based deep eutectic solvent for the extraction and determination of toxic metal ions in herbal medicines

Herein, an eco-friendly, simple, and inexpensive procedure was developed using vortex-assisted combined with deep eutectic solvent-based liquid phase microextraction (VA-LPME-DES) followed by graphite furnace atomic absorption spectrometry. In the present procedure, DES was first synthesized from the combination of l-menthol and (1S)-(+)-camphor-10-sulfonic acid (CSA) in a molar ratio of 5:1, and then it was used as a green and safe extractant instead of common toxic organic solvents. The ability of the presented method was applied for the separation and preconcentration of lead (Pb), cadmium (Cd), mercury (Hg), and arsenic (As) in herbal medicines. After optimizing all the parameters of the experiment, the linear ranges were 0.10–200 µg kg−1 with coefficient of determination (r 2) better than 0.985. The limits of detection were in the ranges of 0.03–0.15 µg kg−1. Relative standard deviation values for intra-day and inter-day of the method based on 7 replicate measurements were in the range of 1.8%–3.6% and 3.1%–7.3%, respectively. The relative recoveries of herbal medicines which have been spiked with different concentrations of metal ions were 91.5%–109.8%. The method was successfully used to analyze the heavy and toxic metals in herbal medicine samples.

Synthesis of Si3N4 powder with a controllable alpha/beta ratio by sol-gel assisted carbothermal reduction and nitridation

The controllable α/β ratio of Si3N4 powder was synthesized using tetraethyl orthosilicate (TEOS), glucose, MgCl2 and YCl3·6H2O by sol-gel assisted carbothermal reduction and nitridation (CRN). This study aimed to investigate the impact of various parameters, including a H2O/TEOS mol ratio of the sol, a C/Si mol ratio, sintering aids, and the temperature of CRN on the phase transformation of α-Si3N4. The results demonstrated that the H2O/TEOS ratio significantly influenced the relative content of α and β phase in Si3N4 by changing the morphological characteristics of SiO2. When the H2O/TEOS ratio was 100, β-Si3N4 powder with an approximate β content over 88 wt% was synthesized at 1500 °C. This remarkable phase transformation was likely facilitated by the eutectic liquid phase consisting of MgSiO3/Mg2SiO4. The SEM image revealed rod-like whiskers with a length around 1.4 μm for the β-Si3N4 grains. Due to the presence of liquid phase, the synthesis of spherical-like α-Si3N4 nano-powder with an α-phase content of 91 wt% was achieved at a lower temperature of 1450 °C, with an H2O/TEOS ratio of 15 and a C/Si ratio of 4. The size of the particles was about 70 nm due to the reduced reaction temperature. Furthermore, without the addition of any sintering aids or Si3N4 seeds, high purity α-Si3N4 with an α phase content approaching 96 wt% could be synthesized at 1500 °C, using an H2O/TEOS ratio of 15 and a C/Si ratio of 4. The resulting α-Si3N4 powder exhibited an extremely regular hexagonal prism shape with a length of approximately 2 μm.

PH-switchable hydrophobic deep eutectic solvent-based liquid phase microextraction for detecting morphine and codeine in whole blood samples followed by HPLC-UV

Prescription opioids are used in clinics for reducing pain, but overdoses and addiction can lead to poisoning. Herein, we report a rapid, straightforward, and cost-effective hydrophobic deep eutectic solvent-based liquid phase microextraction process with HPLC-UV detection for extracting and analyzing morphine and codeine from whole blood samples. The procedure involved synthesizing seven deep eutectic solvents and investigating their pH switchability. Deep eutectic solvents with pH-switchable properties were employed as extractants. Under optimal conditions, the relative standard deviation of 50 μg/L of morphine and codeine in blood samples was 5.4–6.2 % for inter-day measurements and 3.7–4.3 % for intra-day measurements. For both analytes, the calibration graphs showed a linear range of 1.5–300 μg/L and a limit of detection of 0.5 μg/L. The enrichment factor and the extraction recovery of morphine and codeine were 152–––166 and 76 − 83 %, respectively. The results revealed that the addicted person’s blood sample contained both morphine and codeine. The real blood samples spiked with varying doses of codeine and morphine had relative recoveries ranging from 91.8 to 107.0 %, suggesting the method is suitable for real sample analysis.

Simultaneous improvement of mechanical and castability properties of Al-Cu-Mn based alloys by Ca/Ni micro-alloying

Currently one major barrier for the design of cast high-strength and high-toughness Al alloys is hot tearing. In this work, a strategy of combination of squeeze casting and microalloying (Ca/Ni eutectic elements) in Al-Cu-Mn based alloys was employed to inherit the excellent mechanical properties of Al-Cu alloys whilst simultaneously reducing their tendency to hot tearing. The developed alloys exhibit comparable castability (fluidity and hot tear resistance) to A356, which is widely available commercially. However, their comprehensive mechanical properties far exceed those of A356. Trace Ca/Ni additions markedly reduce the grain size of the alloy and simultaneously increase the fraction of intergranular low melting point eutectic liquid phases, which is beneficial to the improvement of liquid feeding. The fine equiaxed grains have excellent thermal shrinkage coordination, while the high volume fraction eutectic liquid phase delays the development of grain cohesive skeleton. Accordingly, the localized shrinkage stress/strain at the hot spot is released timely, thus inhibiting the emergence and propagation of hot cracks in the brittle solidification interval. The diminished hot tearing susceptibility is attributed to the reduced load onset temperature and load values in the hot spot region. A new intergranular bridging mechanism is discovered in low-Ca alloys: based on compositional segregation-induced nucleation of an intergranular bridging skeleton, which strengthens the intergranular adhesive force and effectively reduces the hot tearing tendency of the alloys. The alloys with high-Ca/Ni additions, however, reduce the hot tearing tendency by healing cracks through eutectic liquid phase backfill. The results of the hot tearing experiments of the developed alloys are analyzed with the current hot tearing evaluation criteria. The results demonstrate that the predictions of the Kou's criterion provide guidelines for the design of alloys that are resistant to hot tearing.

Preparation and investigation of green and cheap deep eutectic solvents for determination of essential and toxic metal ions at trace levels in different coffee products

In this research, a vortex-assisted hydrophobic deep eutectic solvent-based dispersive liquid phase microextraction (VA-HDES-DLPME) method was developed to extract some essential (Fe, Mn and Zn) and toxic (Cd and Pb) metal ions from coffee products. After the VA-HDES-DLPME method, the amounts of the metal ions in the HDES-phase were determined by flame atomic absorption spectrophotometry (FAAS). For selective extraction of metal ions, five HDESs (as extraction solvent) were prepared and tested according to the ultrasonic-assisted procedure. Some dispersive solvents were investigated to ensure the dispersion of HDES in the sample solution. In the VA-HDES-DLPME method, heating and centrifugation steps were not required to separate the HDES-phase from the sample solution. Key factors were investigated and optimized to achieve selective and rapid extraction of metal ions. Under optimized conditions, the working range of the VA-HDES-DLPME method for metal ions ranged from 0.03 to 280 μg kg−1. The detection limits of Fe(II), Mn(II), Zn(II), Cd(II), and Pb(II) ions were 0.01, 0.27, 0.02, 0.015, and 0.18 μg kg−1, respectively. Relative standard deviation and extraction recovery for five replicate runs of 5 μg kg−1 of metal ions were in the range of 1.3%–1.9% and 94 ± 4%-98 ± 2%, respectively. Validation of the VA-HDES-DLPME method was tested by studies on three reference materials. In the final step, the VA-HDES-DLPME method was successfully applied to microwave digestion of coffee samples using a standard addition method. The obtained quantitative recoveries showed the good accuracy of the method.

Pressureless sintered high-entropy transition metal diboride ceramics doped with yttrium tetraboride

High entropy diborides (HEBs) are new candidates of ultra-high temperature ceramics. However, it is difficult to obtain dense HEB ceramics via pressureless sintering. In this study, yttrium tetraboride (YB4) was introduced to consolidate (Ti0.25Zr0.25Hf0.25Ta0.25)B2 (4TMB2) ceramics and its effects on the microstructures and mechanical properties were studied. YB4 addition facilitates the densification and grain elongation of 4TMB2 ceramics by forming eutectic liquid phases and eliminating oxide impurities. Relative density of 4TMB2 ceramics containing 5 vol% YB4 reaches to 94.4 % after pressureless sintered at 2000 °C for 3 h. The hardness and toughness determined by indention method are 26.9±1.5 GPa and 5.73±1.65 MPa∙m1/2. This ceramics also exhibit excellent four-point bending creep resistance with the strain rate of 1.48×10−7 s−1 at 1900 °C under 20 MPa. The observed creep behavior is attributed to grain boundary sliding, plastic deformation, grain refinement and enhanced atomic diffusion of Y element, all driven by high-temperature stresses.

Intermetallic phase evolution and strengthening mechanisms of the titanium and stainless steel lap joints welded by interrupted pulsed arc welding

The study is focused on analyzing the intermetallic phase evolution and strengthening mechanisms of the titanium alloy and stainless steel (Ti-SS) seam-welded joints using interrupted pulsed arc welding (IPAW). The precise adjustment of welding parameters for the IPAW technique allowed for the successful creation of two different joining modes for Ti-SS joints: contact reactive brazing and fusion modes. The homogeneous composition in the brazing joints was achieved by the formation of a diffusion-driven eutectic liquid phase at the joining contact, resulting in an unusual eutectic structure consisting of β-Ti and TiFe. The molten pool at high temperatures caused an uneven distribution of composition and energy throughout the fusion joints. The fusion joints consisted of a Ti-rich layer, containing β-Ti and TiFe phases near the TC4 side, and a Fe-rich layer, containing TiFe2/TiCr2 and α-Fe phases near the 304SS side. The shear-bearing capacity of the joints exhibited an initial increase and subsequent decrease as the heat input increased. The low heat input resulted in the formation of the unwelding zone, which significantly reduced the shear resistance of the joints. With the increase of the heat input, a reduction in shear strength occurred due to the accumulation of TiFe2 brittle phases associated with the shift of the joining mode from the brazing to the fusion. The shear force decreased after reaching its maximum value, despite the joints being fully joined and the joining area expanding.

Understanding the formation mechanism of SiC/Al joints by U-TLP bonding with the inactive Zn interlayer

The ultrasonic-assisted transient liquid phase (U-TLP) bonding process is extremely fast, which is a great challenge to reveal the inherent mechanisms. Understanding the joint formation mechanism of U-TLP is essential for the joining process design. In this study, the SiC ceramics and 6063Al alloys were joined by U-TLP using a Zn interlayer. The process of removing the oxide film on the base metal involved cracking, flaking off, suspending, and fragmenting. The migration of the eutectic liquid phases frontier was very fast (within 1 s). The relationship between the thickness of the liquid layer and the ultrasonic action time was a power function. The typical microstructure of the SiC/6063Al joints was SiC/amorphous Al2O3/Zn-Al eutectic/ Zn-Al eutectoid/6063Al. The shear strength of SiC/6063Al joints increased with the interfacial bonding ratio and reached up to 27 MPa for the ultrasonic action time of 5 s. The metallurgical bonding at the SiC/bond metal interface was formed through the amorphous Al2O3 transition layer. The formation mechanism of the Al2O3 reaction layer was revealed based on the thermodynamics, kinetics, and acoustics cavitation theory. This will provide a guideline for the future U-TLP process design.

Deep eutectic solvent liquid phase microextraction, powered by ultrasonic system, for determination of β-carotene in food samples

The research work is mainly concerned with the extraction of β-carotene, which is a terpenoid compound, from food and fruit samples using deep eutectic solvent based liquid phase extraction. Deep eutectic solvent liquid phase microextraction method, powered by ultrasonic mixing, (DES-UP-LPME) was carried out with deep eutectic solvent (DES) consisting of tetrabutylammoniumbromide (TBAB) and decanoic acid (DA). Key parameters such as pH, sample volume, tetrahydrofuran (THF) volume, DES type and volume, matrix effect, ultrasonication/centrifugation time were optimized to increase the extraction efficiency of β-carotene. Quantitative recoveries were obtained when pH, TBAB:DA ratio and sample volume were 3, 1:3 and 30, respectively. The limit of detection (LOD) and limit of quantification (LOQ) were found to be 0.005 µg/mL and 0.015 µg/mL, respectively. Various food samples were analyzed spectrophotometrically by using the developed DES-UP-LPME at 450 nm. The addition/recovery studies were also performed on water samples to evaluate the accuracy of the method.

Optimization of vortex-assisted hydrophobic magnetic deep eutectic solvent-based dispersive liquid phase microextraction for quantification of niclosamide in real samples.

In this manuscript, a green and fast vortex-assisted hydrophobic magnetic deep eutectic solvent-based dispersive liquid phase microextraction (VA-HMDES-DLPME) method was developed for the selective extraction and determination of niclosamide in read samples, including rice, medicine tablets, and water samples. Here, hydrophobic magnetic deep eutectic solvents were used as the extracting solvent without requiring any centrifugation step. In the light of preliminary experiments, important parameters, such as volume of extraction solvent, pH, acetonitrile volume and vortex time, affecting the extraction efficiency of niclosamide were optimized using a Box-Behnken design. The linear dynamic range (0.25-120 µg/L), the limit of detection (0.08 µg/L), the limit of quantitation (0.25 µg/L), preconcentration factor (180), and enrichment factor (130) of the method were determined using optimized data. In particular, the validation parameters of the optimized VA-HMDES-DLPME, including robustness, matrix effect accuracy, and precision, were investigated. In addition to this, intra- and inter-day precisions were determined as≤3.5 % and≤4.1%, respectively. Finally, the optimized method was successfully used for the extraction of niclosamide in the selected samples prior to spectrophotometric analysis.

An air-assisted dispersive liquid phase microextraction method based on a hydrophobic magnetic deep eutectic solvent for the extraction and preconcentration of melamine from milk and milk-based products.

In the current research, a fast and sustainable air-assisted hydrophobic magnetic deep eutectic solvent-based dispersive liquid phase microextraction followed by UV-Vis spectrophotometry measurements was optimized for the extraction and determination of melamine in milk and milk-based products. The central composite design was applied for the optimization of factors affecting the recovery of melamine. Quantitative extraction of melamine was achieved using hydrophobic magnetic deep eutectic solvents prepared from a mixture of octanoic acid, aliquat-336, and cobalt(II) chloride. The optimum conditions for extraction were found as follows: 6 extraction cycles, pH 8.2, extraction solvent volume 260µL, and acetone volume 125µL.Interestingly, a centrifugation step was not required to achieve phase separation. Under the optimum conditions, melamine was determined in the linear range of 3-600ngmL-1, the limit of detection (3Sblank/m) of 0.9ngmL-1, and the enrichment factor of 144. The validation of the method was investigated by the analysis of reference materials. Consequently, the method was successfully applied for the analysis of melamine residues in milk and milk-based products.

A novel diffusion bonding of 6063Al based on a mode of diffusion-migrating and suspension-broken of surface oxide film

The breaking of surface oxide film in a technology area of ultrasonic-assisted diffusion joining manufacturing of large-size structure components is a challenge. In this work, a novel method of breaking surface oxide film of Al alloys based on first diffusion-migrating and then suspension-broken was investigated. Diffusion bonding of 6063Al alloys was performed by Zn interlayer at temperature below 400 °C. The oxide film migrated away from the Al alloy base metal by solid phase diffusion at 360 °C, and remained in the joint as a nanoscale oxide film. When temperature increased to 390 °C, the oxide film suspended in the Zn–Al eutectic liquid phase were rapidly broken up into small fragments through an instantaneous ultrasonic action (only 0.3 s). The change of acoustic pressure in the liquid metal proved that the suspended continuous oxide film was broken by the micro-jet acted simultaneously on both sides of oxide film induced by the ultrasonic cavitation effect. Finally, the inter-diffusion between Zn and Al at 360 °C was promoted by a longer holding time to obtain the homogeneous joint composed by Zn–Al eutectoid phase containing oxide fragments, and had a higher strength than the base metal. The breaking of oxide film and joint homogenization were performed under pressure-less condition, which effectively avoided the squeezed-out of the liquid phase. This technology shows a great potential for manufacturing large-size joint of industrial products.

Effect of Intensification Pressure on Eutectic Si Segregation of Al-12Si-1Cu Alloy in Squeeze Casting

Squeeze casting is an advanced technology to produce aluminum alloy components with excellent mechanical property. Due to good fluidity and castability, the Al-Si alloy is the most common aluminum material in squeeze casting. However, the segregation in solid α-Al phase and liquid eutectic Si phase happens during solidification, which leads to microstructural inhomogeneous in the final microstructure. In this study, the eutectic Si segregation of Al-12Si-1Cu alloy under different intensification pressure in squeeze casting was investigated by Optical Microscopy (OM). The results show that increasing intensification pressure promotes the eutectic Si segregation at center zone, while the eutectic Si phase at skin zone is not much influenced. Increasing the intensification pressure from 65 MPa to 140 MPa, the segregation degree of eutectic Si at center zone increases from 0.05 to 0.29, while the segregation degree at skin zone levels at 0.2. Under high intensification pressure, the feeding effect of liquid phase at center zone is prominent, which results to high tendency of eutectic Si segregation in the final microstructure.

An effervescence-assisted switchable deep eutectic solvent based liquid-phase microextraction of triazole fungicides in drinking water and beverage

A new effervescence-assisted switchable deep eutectic solvent-based liquid phase microextraction (EA-SDES-LPME) combined with HPLC-UV was developed for determination of common triazole fungicides in drinking water and beverages, including myclobutanil, flusilazole, hexaconazole and bitertanol. The alternative extraction solvent was prepared with hexafluoroisopropanol and dipropylamine with the merits of time-saving, easy to collect and cost-effectiveness. The SDES can be reversibly switched between hydrophilic and hydrophobic states by pH adjustment. The homogeneous extraction was achieved under the hydrophilic form of SDES, and the bi-phase separation was obtained easily by adjusting pH value to restore the original hydrophobicity. Moreover, the characterization of SDES was investigated by FTIR and 1H NMR. The main variables affecting extraction efficiency were optimized in detail. Under the optimal conditions, the proposed method shows desirable precision (RSDs less than 18.5%) and acceptable recovery (72.6–95.4%). The lower limits of detection and limits of quantitation were found to be in the range of 1–2 μg L-1 and 5–10 μg L-1, respectively. The formation mechanism of SDES and the extraction mechanism for target analytes were investigated by density functional theory. The proposed methodology was simplicity, sensitive, time-saving and successfully applied to determine triazole fungicides in drinking water and beverages, making it an alternative technique for the analysis of trace analytes with satisfactory sensitivity.

Deep eutectic solvent-based electromembrane hollow fiber liquid phase microextraction for determining Pb in water and food samples

In the present work, the determination of Pb using the electromembrane hollow fiber liquid phase microextraction with a deep eutectic solvent and graphite furnace atomic absorption spectrometry detection (DES-EM-HFLPME-GFAAS) was proposed. First, Pb(II) in the sample was converted to the anionic form of Pb-oxyanion under alkali conditions. Then, the electro-assisted technique was applied to facilitate the anion passing through the supported liquid membrane into the phase of deep eutectic solvent mixed with buffer solution. Finally, GFAAS was applied for monitoring the total lead in samples. The important parameters affecting the method efficiency were studied. Under optimized conditions, the linear range was observed in the range 0.036-1.0 ng/mL. The limit of detection and limit of quantitation were 0.011 and 0.036 ng/mL, respectively. Precision as %RSD was obtained from 1.03 to 3.49%. The enrichment factor and the preconcentration factor were 111 and 750, respectively. The proposed method was applied to determine lead in water and food samples (i.e., drinking and tap water, canned food, and vegetables) with acceptable recoveries from 86.70 to 116.0%. The method was successfully applied to determine the amount of lead in the standard reference materials, and the concentrations measured were not significantly different at 95% of confidence level from the certified values.

Enhanced Ti3AlC2/Zircaloy-4 interfacial bonding by using copper as an interlayer

We propose a novel strategy for the high-strength joining of Ti3AlC2 and Zircaloy-4 by introducing copper as an interlayer. The interfacial microstructure reveals spontaneously formed Cu–Zr eutectic liquid phase wet Ti3AlC2 ceramic, generating a ZrC layer instead of brittle ZrxAly at the interface, enhancing the Ti3AlC2/Zircaloy-4 joint strength.

Method to Rapidly Identify Potential Solvent Systems for Crystallization of Cocrystals

This study aims at easing the design of crystallization and the cake washing step of cocrystals. It is assessed if solvent systems can be classified based on the dissolution behavior of the cocrystal by leveraging on the solubility of its pure components. Solubility data of pure components are typically readily accessible data in the pharmaceutical industry at an early stage of development. For the three model systems considered in this study, the composition of eutectic liquid phases was determined at 20 °C in numerous solvent systems and compared with the solubility of pure components at the same conditions. In the solvent systems in which the cocrystal dissolves congruently, the solubilities of the pure components are similar. Incongruent dissolution behavior is in turn consistently observed if the solubilities of the pure components differed by at least one order of magnitude. For these solvent systems, the eutectic liquid phases are consistently enriched in the more soluble component. Comparison of the solubilities of the pure components thus enables determination of the component that needs to be charged in excess to reach thermodynamic stability of the cocrystal, which is particularly relevant for the design of screening and solubility experiments. Finally, highly asymmetric phase diagrams, which are not suitable for crystallization and cake washing purposes, are easily identifiable by highly dissimilar solubilities of pure components.