Optimal Separation Conditions Research Articles

An azine-linked covalent organic framework as stationary phase for separation of environmental endocrine disruptors by open-tubular capillary electrochromatography

In recent years, covalent organic frameworks (COFs) play an important role in the field of chromatographic separation. However, COFs are used rarely in open-tubular capillary electrochromatography (OT-CEC) so far, and the reported methods have not been applied to actual sample analysis. Herein, a novel azine-linked COF (N0-COF) coated capillary was prepared as OT-CEC separation channel and a new method for separation and detection of environmental endocrine disruptors, i.e., bisphenol A (BPA) and its analogues was established. Under optimal separation conditions, the analytes were baseline separated by the N0-COF coated capillary with 20 min. The intra-day, inter-day and column-to-column relative standard deviations were 0.07–2.99%, 1.05–3.20% and 1.31–5.83% for the migration time; 1.68–5.50%, 1.52–9.24% and 4.04–9.14% for the peak area. The method was further applied to separate and determine BPA and its analogues in beverage samples, and the recovery ranged from 91.0–112.0%.

A rapid enantioseparation system of capillary electrochromatography modified by electrostatic adsorption with transfersomes.

Transfersomes were a special kind of nanomaterials with higher deformability and flexibility. A rapid method for coated-column preparation using anionic transfersomes as a coating material by electrostatic adsorption was developed. With carboxymethyl-β-cyclodextrin added in running buffer as the chiral selector, the capillary electrochromatography enantioseparation system based on the transfersomes-coated column modified by electrostatic adsorption was established for the first time. Propranolol and metoprolol acted as model drugs to evaluate the enantioseparation performance, these two basic drugs achieved baseline separation with satisfactory resolution and selection factor in this transfersomes-electrochromatography system but only partial separation in bare column system. In order to get the optimal separation condition, concentration of chiral selector, buffer pH, and applied voltage were systematically investigated. A rapid and efficient enantioseparation electrochromatography system was established and showed that transfersomes as the stationary phase could efficiently improve chiral separation effect.

Minor Actinides Separation by N,N,N’,N’,N’’,N’’-Hexaoctyl Nitrilotriacetamide (HONTA) Using Mixer-settler Extractors in a Hot Cell

ABSTRACTA continuous counter-current test to separate minor actinides (MAs: Am and Cm) by N,N,N’,N’,N’’,N’’-hexaoctyl nitrilotriacetamide (HONTA) as an extractant was performed using mixer-settler extractors installed in a hot cell. Nitric acid of 0.08 M (mol/dm3) containing MAs and rare earths (REs) recovered from high-level liquid waste was used as the feed, and the experiment was conducted for 14 h. MAs were extracted by 0.05 M HONTA dissolved in n-dodecane, with Am and Cm being recovered at 94.9% and 78.9%, respectively. HONTA hardly extracted Y, La, and Eu from the feed (99.9% for Y, 99.9% for La, and 96.7% for Eu), most of which were distributed to the RE fraction. A portion of Nd was extracted by HONTA, and consequently the ratio of Nd in the RE fraction was 83.5%. HONTA could separate MAs and REs by adjusting the nitric acid concentration without using complexants. In addition, the concentrations of MAs and some REs in each stage were calculated using a simulation code, and the results are consistent with the experimental values. This code indicates that the ratios of MAs in the MA fraction and REs in the RE fraction could be ≥99% by optimizing separation conditions.

A new strategy for development of eco-friendly RP-HPLC method using Corona Charged Aerosol Detector and its application for simultaneous analysis of risperidone and its related impurities

Green analytical chemistry is primarily directed towards minimization of the amount of waste associated with either the sample preparation or analysis. Among different chromatographic methods, liquid chromatography is considered the least green, allowing for various possibilities for greening. Using green solvents such as ethanol or acetone in RP-HPLC, as an alternative to acetonitrile, is recently attracting an attention. Both ethanol and acetone are characterized with low toxicity, with certain drawbacks limiting their regular use in RP-HPLC. Ethanol has low eluotropic strength and causes high backpressures, while acetone shows high UV cut-off, making it unsuitable for UV/Vis detection. To overcome the existing problems, Corona Charged Aerosol Detector was employed for development of RP-HPLC methods for separation of risperidone and its structurally related impurities with either ethanol or acetone as organic modifier. The methods were optimized by experimental design methodology, while optimal conditions for separation were determined using Derringer's desirability function. Detailed assessment of 3D surface plots of Derringer's desirability function enabled selection of 0.6 mL min−1 flow rate and 20% (v/v) organic modifier content as optimal when using ethanol, while in case of acetone mobile phase flow rate was 0.8 mL min−1 and organic modifier content 17% (v/v). Methods were validated and their eco-friendly character was confirmed through Green Analytical Procedure Index (GAPI). Although both methods are ecologically acceptable, the main drawback is reflected in the fact that no recycling or another waste treatment method exist. In the end, acetone was prioritized over ethanol, due to lower health hazard and decreased amount of generated waste.

The Separation Optimization of Berberine in Anting-Anting Plants (Acalypha Indica Linn) using High Performance Liquid Chromatography (HPLC)

Anting-Anting plants (Acalypha Indica Linn) is a plant widely found in Indonesia. This plant has potential as an antimalarial, antidiabetic, and antitoxic drug. Ethyl acetate extract of this plant contained isoquinoline alkaloid, berberine which confirmed by LC-MS spectra on m/z 321,2561. Then, this study was conducted to determine the optimum conditions of separation and determination the berberine level existed on ethyl acetate extract of Anting-Anting using HPLC. The separation was optimized by varying flow rate of eluent (0.6 mL/min, 0.8 mL/min, 1.0 mL/min), mobile phase (methanol: TFA 0.1% (50:50 v/v) and acetonitrile: TFA 0.1% (60:40 v/v)). The separation was using HPLC with C18 (ODS) 4.6 × 250 mm, 5 μm column, isocratic method at various wavelengths (290 nm, 315 nm, and 345 nm). The optimum separation condition was obtained at flow rate 1 mL/min with mobile phase methanol: TFA 0.1% (50:50 v/v) and UV detector wavelength at 345 nm. The result showed that the berberine level of Anting-anting in ethyl acetate fraction was 11,82030 μg/mL.

Extraction of triply charged metal cations in aqueous phase-separating system antipyrine–sulfosalicylic acid–water

Extraction of macro amounts of triply charged metal cations (0.01–0.05 mol L−1) in aqueous phase-separating system antipyrine–sulfosalicylic acid–water containing no organic solvent is studied. Optimum conditions for phase separation are established and the influence of the concentrations of the major components, inorganic acids (H2SO4, HCl), salting-out agents, and the volume of the aqueous phase on the process in question is determined. It was found that the optimum antipyrine/sulfosalicylic acid ratio in the system was (1.5–2.0): 1.0. The introduction of inorganic salting-out agents causes the volume of the organic phase (0.8–1.8 mL) to increase to 2 mL and more. The extractability series of triply charged metal ions is as follows: Tl > Fe > Sc > In > Ga. It was shown that inorganic salts and hexamine influence the degree of extraction of metal cations and that inorganic acids and water affect the distribution mechanism and the composition of the complexes. The half-extraction pH values (pH1/2) of the cations are calculated and correlations between the pH1/2 values, the ionic radii of the cations, and the polarization ability of the metal ions are established.

Synthesis of Poly(Ethyl Eugenyl oxyacetate) as Carrier For Separation of Heavy Metal Ions Fe(III), Cr(III), Cu(II), Ni(II), Co(II), and Pb(II) Using Liquid-Liquid Extraction Method

Synthesis of poly(ethyl eugenyl oxyacetate), PEEOA, has been conducted. The compound was applied to separate Fe(III), Cr(III), Cu(II), Co(II), and Pb(II) using a liquid-liquid extraction method. The effect of pH, polyeugenyl ethyl oxyacetic ion carrier concentration, extraction time, and metal concentration was optimized to obtain optimum condition. The result showed that the synthesized polyeugenyl ethyl oxyacetic has a yellow color with a melting point 127-1300 °C and yield efficiency of 87%. The formation of polyeugenyl ethyl oxyacetid confirmed with IR spectroscopy and 1H-NMR spectra. The appearance of the absorption band at 1759 cm−1 as stretching vibration of carbonyl (C=O) esther and 1280 and 1373 cm−1 as stretching vibration of carbonyl (C-O-C), chemical shift at 4,74 ppm for proton methylene (CH2-C=0) and chemical shift at 1,27 ppm for proton methyl (O-CH2-CH3). The optimum condition for ion separation has occurred at pH 3-6 for ion Fe(III), pH 5 for ion Cr(III), Ni(II), Co(II), Cu(II), and Pb(II). The carrier volume was optimum at 5 mL (1 × 10−3 M) for Fe (III), 10 mL for Cr(III), Ni(II), and Co(II), and 15 mL for Cu(II), and Pb(II). The optimum extraction time was 2,5 and 20 hours for ion Fe(III) and Cr(III), respectively, and 36 hours for ion Cu(II), Ni(II), Co(II) and Pb(II). The concentration range of metals ion accurately extracted was 0.75 - 5 x 10−4 M for ion Fe(III); 0.75- 2.50 x 10−4 M for Cr(III), Ni(II), and Co(II) and 0.75-1 x 10−4 M for Cu(II) and Pb(II). Compared to other metal ions the respond polyeugenyl oxyacetic acid was best Fe(III) with selectivity order Fe(III) > Cr(III) > Cu(II) > Pb(II) > Ni(II) > Co(II).

Improving separation optimization in capillary electrophoresis by using a general quality criterion

In this paper we extend the use of the quality criterion t’ to optimize separations in capillary electrophoresis (CE). The theoretical parameter t’ takes into account not only the relative separation between a given pair of compounds but also their separation from the neutral species migrating with the electroosmotic flow (EOF). Furthermore, it can be composed for complex mixtures as a global multicriterium optimization function T′, for a rapid, simple and reliable selection of optimized separation conditions by mathematical maximization. Here, we demonstrate the applicability of T′ using as a variable the electrophoretic mobility (me) for the optimization of pH in the separation of a mixture of amyloid beta (Aβ) peptide fragments. In addition, it is shown the versatility of T′ using other variables related to me, which do not require experimental measurements. This is the case with ionizable compounds as the Aβ peptide fragments, whose charge-to-mass ratios can be calculated if accurate pKa values are available in the literature. The excellent performance of T’ for Aβ peptide fragments is further validated optimizing the pH for the separation of mixtures of harmala alkaloids (HAlks) and quinolone antibiotics.

Green flotation of polyethylene terephthalate and polyvinyl chloride assisted by surface modification of selective CaCO3 coating

Abstract Plastic flotation was a promising separation method for efficient recycling of waste plastics. Aiming to avoid the destruction of original surface and secondary pollution, a novel flotation process based on calcium carbonate (CaCO3) coating was proposed for separation of polyvinyl chloride (PVC) and polyethylene terephthalate (PET). The mechanism of CaCO3 coating was researched via scanning electron microscope (SEM), X–ray photoelectron spectroscopy (XPS), X–ray diffraction (XRD), zeta potential, Fourier transformed infrared spectroscopy (FT–IR), and solution chemistry analysis. High polarity of C–Cl on PVC surface resulted in selective adherence of Ca2+ on PVC surface, and Ca2+ was a bridge between plastic surface and CaCO3 particles. The separation of PVC and PET was optimized by response surface methodology (RSM) combining Box–Behnken design (BBD). Optimal pretreatment conditions for flotation separation of PVC and PET were 0.11 g CaCO3, temperature 50.6 °C, treatment time 20 min, and pH 10.1. The purity and recovery of PVC could be 100% and 99%, respectively.

Effective production of lactosucrose using β-fructofuranosidase and glucose oxidase co-immobilized by sol-gel encapsulation.

The production of lactosucrose is hampered by the costly use of β‐fructofuranosidase, which shows poor stability and a low efficiency in transfructosylation activity. Immobilization could improve enzyme stability and realize the cyclic utilization at a reduced cost. In order to eliminate the by‐product inhibition and improve the transfructosylation efficiency, β‐fructofuranosidase and glucose oxidase were co‐immobilized by sol–gel encapsulation and the subsequent production efficiency of lactosucrose was investigated. The as‐prepared immobilized bi‐enzymes retained 85.39% of their initial activity at an enzyme concentration of 1.47 mg/g·sol during immobilization and showed great operational stability (maintaining 78.5% of their initial activity) after 15 consecutive reuses. The yield of lactosucrose synthesized by immobilized bi‐enzymes reached 160.8 g/L under the optimized conditions, which was relatively higher than previous reported results. Moreover, the yield of lactosucrose synthesized by immobilized bi‐enzymes was significantly improved as compared to that synthesized by immobilized β‐fructofuranosidase. HPLC and NMR spectrum results confirmed the presence of lactosucrose during immobilized bi‐enzymes catalysis. Furthermore, a relatively high purity of lactosucrose was obtained (87.4% determined by HPLC) after separation with Diaion UBK535 calcium ester resin, and the optimal conditions for separation of lactosucrose were investigated. These results indicated that the co‐immobilization of β‐fructofuranosidase‐glucose oxidase was helpful to improve the production of lactosucrose with low costs, which can be used in continuous lactosucrose production in food industry in advantages of high stability and reusability. And the as‐prepared lactosucrose with high purity can be applied to many kinds of food as functional additives.

Experimental Design Approach to Optimize HPLC Separation of Active Ingredients, Preservatives, and Colorants in Syrup Formulation

Abstract Background: Preservatives and colorants in pharmaceutical products may be highly toxic, especially for sensitive individuals, when they are used in excessive amounts. In this context, sensitive and non-labor-intensive analytical methods with short analysis time for simultaneous quantification of these additive substances in drugs can meet all requirements in quality control laboratories. Objective: The aim of the study was to develop a simultaneous HPLC method for the analysis of pseudoephedrine HCl and guaifenesin, along with preservatives, methyl paraben and propyl paraben, and colorants, ponceau 4R and sunset yellow, in a syrup sample. Methods: Optimum conditions of HPLC separation were determined by Box-Behnken experimental design. Four independent variables of the separation were pH (6.0, 6.5, and 7.0) and flow rate of the mobile phase (2.0, 2.2, and 2.4 mL/min) and mobile phase ratios for the first and second gradient elutions (75, 80, and 85% for Gradient 1 and 50, 55, and 60% for Gradient 2 in terms of phosphate buffer percent, respectively). Results: The optimum conditions were found to be pH, 6.3; flow rate, 2.4 mL/min; and mobile phase ratios (phosphate buffer-acetonitrile) for Gradient 1 and 2, 85+15 (v/v) and 60+40 (v/v), respectively. Conclusions: Simultaneous analysis of all compounds was achieved by using this HPLC method with a short run time below 10 min. Highlights: This simple, rapid, and validated method is convenient and applicable for routine analysis of pharmaceutical products having similar composition without the need for any extraction step.

Optimal Physical Coil Separation Condition for Wireless Charging System

Now-a-days, wireless transfer of electric power has received much attention in the world arena. As a safe, reliable and convenient technology, Magnetic resonance coupling (MRC) based wireless power transfer (WPT) system shows a remarkable ability to power up in a wide range from mW to kW range. In this paper conventional magnetic field analysis with maximum power transfer theorem has been used to explain the frequency characteristics of the transferred load power. The intensity of magnetic field, induced receiver voltage, physical air gap of coils relating to the dimension of the coils has been examined. The experimental results are well agreed with the theoretical results. The acquired analysis depicts the optimal physical separation condition relating to the size of the charging coils of a WPT system.

Precise Measurement and Controlled Tuning of Effective Window Sizes in ZIF-8 Framework for Efficient Separation of Xylenes.

Metal-organic frameworks (MOFs) are the promising nanomaterials for separation of molecules with close dimensions and structures, such as various types of isomers. The efficiency of separation can be greatly enhanced if the apertures of the nanosized windows, controlling the diffusion of a particular molecule inside the cavities, are fine-tuned by external stimuli. We report the new approach for precise measurement of window sizes in ZIF-8 MOF and employ it in efficient separation of xylenes, which is of high practical importance. For this sake, we synthesized ZIF-8 with embedded stable nitroxides in the pores and applied electron paramagnetic resonance spectroscopy for in situ kinetic measurement of the diffusion of various guest molecules through the material. Slight variation of temperature within 298-333 K allowed tuning of the windows and reaching optimum conditions for separation of p-, m-, and o-xylenes with the efficiency up to 92-95%. The developed methodology provides deeper understanding of steric and kinetic aspects of molecular diffusion in ZIF-8 and paves the way to rational optimization of other MOF-based separation applications.

Enantioseparation of three isomeric α-(chlorophenyl)propanoic acid by countercurrent chromatography and investigation of chlorine substituent through characterization of inclusion interaction

The influence of chlorine substituents in chiral separation of three racemic 2-(chlorophenyl)propanoic acids by countercurrent chromatography using hydroxypropyl-β-cyclodextrin as a chiral additive were mainly investigated in the present paper, including 2-(2-chlorophenyl)propanoic acids, 2-(3-chlorophenyl)propanoic acids and 2-(4-chlorophenyl)propanoic acids. The influences of chromatographic conditions on the retention behavior were studied by enantioselective liquid-liquid extraction experiments using the methodology of response surface It was found that 2-(3-chlorophenyl)propanoic acids could be successfully chiral separated by countercurrent chromatography, while no resolution was achieved for racemic 2-(2-chlorophenyl)propanoic acids and 2-(4-chlorophenyl)propanoic acids under optimized separation conditions. The formation of 1:1 stoichiometric inclusion compounds between 2-(3-chlorophenyl)propanoic acids and HP-β-CD was determined by UV spectra measurements. The inclusion constants for 2-(3-chlorophenyl)propanoic acids and HP-β-CD were determined by the Benesi-Hildebrand equation. Meanwhile, the inclusion constants of 2-(3-chlorophenyl)-propanoic acid enantiomer and HP-β-CD were obtained by the pesudophase retention equation in countercurrent chromatography. Furthermore, the inclusion interactions of the three racemates with HP-β-CD were also investigated by the molecular docking. The results obtained from UV spectra measurements and molecular docking showed that the racemate with chlorine substituents in meta-position presented the highest enantiorecognition while the racemates with chlorine substituents in ortho-position had the lowest enantiorecognition. The above results further indicated that forming a stable inclusion complex between racemate and chiral selector is a prerequisite for a successful enantioseparation and at the same time, the difference in inclusion capacity between the two enantiomers is also essential for the enantioseparation.

Pretreatment of Chlorine Dioxide Solution for Pulp Bleaching

Adsorbable organic halogen (AOX) is mainly produced by the reaction of residual lignin and chlorinated bleaching agents during bleaching processes. The formation of AOX can be reduced via optimization, addition of chemical additives, and/or pretreatment processes. Only a few studies exist on the effective purification of chlorine dioxide solutions and its effect on AOX reduction. In this paper, the effects of the extraction pressure, temperature, pH, and extraction time on the chlorine gas removal rate (CR) were evaluated. In addition, a response surface model was established to optimize the chlorine gas removal. The temperature of chlorine gas separation was optimized at 39.85 °C, with a separation pressure of –51.20 kPa and solution pH of 1.94, providing an estimated CR of 70.93% under the optimum separation conditions. Chlorine dioxide solutions with and without chlorine gas removal were used for pulp bleaching. AOX formation was reduced by 69.57% at the same 2.0% chlorine dioxide dosage, while the pulp brightness decreased by 3.0%ISO. In addition, AOX formation was reduced by 27.90% at the same bleached pulp brightness (80.00%ISO). The results provide theoretical support for the production of high-purity chlorine dioxide solutions and the development of clean pulping and papermaking processes.

New pretreatment method for high-tension electrical separation of zircon from quartz

Abstract Electrostatic separation is one of the mineral processing methods based on mineral conductivity. This method has some significant problems such as being sensitive to humidity, high middling product, and impurity of non-conductive minerals. In this study, a new pretreatment method was proposed for the separation of zircon from quartz before electrostatic separation to solve these disadvantages. In this regard, two stages of pretreatment were applied which involved using collector of sodium dodecyl sulfate (SDS) for adjusting wettability of the zircon surface and spraying electrolyte aqueous solution to increase conductivity of the quartz surface. The effects of important parameters including pH, collector concentration, conditioning time, and concentration and type of electrolyte on the process efficiency were evaluated. The results showed that the optimal conditions of high-tension electrical separation were pH of 4, SDS concentration of 1×10−4 mol/L, conditioning time of 4 min and NaCl as an electrolyte with concentration of 4.27 mol/L. Separation efficiency of 95.12% was achieved in optimum conditions. This pretreatment method can be successfully used before high-tension electrical separation to separate the conductive or non-conductive minerals with various compositions.

Soundproofing flexible polyurethane foams: Effect of chemical structure of chain extenders on micro-phase separation and acoustic damping

In this study, a new high-performance acoustic damping flexible polyurethane foam (FPUF) was successfully designed and fabricated using synthesized linear saturated aliphatic polyester resin as polyol, methylene diphenyl diisocyanate, and ethylene glycol, monoethanolamine, and ethylenediamine as chain extenders and other reagents by one-shot bulk polymerization (isocyanate index = 100 and water content = 2.5%). The effect of the chemical structure of different chain extenders on micro-phase separation and acoustic damping properties of FPUFs were investigated using comprehensive characterization techniques such as atomic force microscopy (AFM), Fourier transform infrared spectroscopy (FT-IR), compressive strength, optical microscope, and‏ ‏impedance tube. It was indicated that the micro-phase separation degree of the FPUF matrix increased with increasing amine content in the chain extender structure due to the more bidentate hydrogen bondings formation between urea-urea groups. Also, by increasing micro-phase separation, average cell sizes decreased and compressive strength, open-cell contents%, cell walls roughness, and cell size distribution of FPUFs increased. According to the sound absorption spectra, it was found that sound absorption efficiency of FPUF containing DEA was higher than FPUF manufactured by EG by 13.23% in the range of 1500–4000 Hz due to the increase of the amine content of chain extenders. These results indicate that the acoustic properties of FPUFs can be explained with the synergistic actions of micro-phase separation including the viscoelastic behavior of hard-soft segments and increasing of airflow pathway leading to dissipating of the kinetic energy of sound waves. Finally, the results revealed that soundproofing FPUFs with an optimum condition for micro-phase separation and drainage flow can be a promising candidate for using as sound insulating materials in transportation industries such as airplanes, trains, etc.

Экспресс-идентификация и определение натамицина в пищевых продуктах методом ультравысокоэффективной жидкостной хроматографии/квадруполь-времяпролетной масс-спектрометрии высокого разрешения

Предложена методика экспресс-идентификации и определения полиенового антибиотика натамицина в пищевых продуктах методом ультравысокоэффективной жидкостной хроматографии в сочетании с квадруполь-времяпролетной масс-спектрометрией высокого разрешения. Диапазон определяемых содержаний натамицина составил от 0.5 до 100 нг/г. Для определения обнаруженного натамицина предложено использовать метод стандартной добавки. Относительное стандартное отклонение результатов анализа не превышало 0.12. Продолжительность идентификации проб 20 мин, определения натамицина – 40 мин

Efficient separation of lead and antimony metals from the Pb-Sb alloy by super-gravity technology

The Pb-Sb alloy was obtained during the pyrometallurgical processing of jamesonite (Pb4FeSb6S14). To effectively separate lead and antimony metals from the Pb-Sb alloy, an innovative approach of super-gravity technology was introduced in the current study. The super-gravity technology plays a significant role in enhancing mass transfer and phase migration of heterogeneous phases as the interfacial tension between different phases will become insignificant. The theoretical calculation of separating efficiencies based on the lever principle of Pb-Sb phase diagram was investigated. The effect of the super-gravity field on Pb-Sb alloys and the corresponding mechanism of filtrating were discussed. With the help of scanning electron microscopy-energy dispersive spectroscopy, metallographic microscopy and X-ray diffraction methods, it demonstrated that the lead phase migrated to the bottom of the sample along the super-gravity direction, whereas almost all of the antimony-rich phase accumulated along the opposite direction. As a step further, the Pb-Sb alloy was separated effectively by the filter in the super-gravity field, and the separating efficiency increased with the increasing of the gravity coefficient (G) within the range of G ≥ 50. With an optimized separation condition T = 533K (260 °C), G = 450, dpore = 48 μm and t = 210 s, the mass fraction of Pb in the filtrated lead phase reached 85 wt%, which was close to the theoretical separation value 88.8 wt% based on the phase diagram of the Pb-Sb alloy, and the mass fraction of Sb in the residue antimony-rich phase exceeded 91 wt%.

Separation of valuable elements from NiMH battery leach liquor via antisolvent precipitation

Rare earth elements (REE) have been selectively recovered from NiMH battery leach liquors by antisolvent precipitation. The active anode material was leached using sulfuric acid. The REE were then separated from the other elements by precipitation as sulfates after addition of either ethanol or 2-propanol (antisolvent). In a second step, Ni and Co are separated as sulfates by the same technique. The concentration of elements in different acid alcohol mixtures at 25 °C and −10 °C respectively are presented as a function of time after addition of the alcohol, and the optimum conditions for separation of the REE in pure form are presented. Under optimum conditions, 5.6 mol/L (Organic/Aqueous (O/A) volumetric ratio = 0.7) of 2-propanol at 25 °C, 82% of the REE have precipitated 3 h after addition of the antisolvent and the purity is 99.9%.