Type Of Organic Solvent Research Articles

Thin-film hydration preparation method and stability test of DOX-loaded disulfide-linked polyethylene glycol 5000-lysine-di-tocopherol succinate nanomicelles

A novel redox-responsive PEG-sheddable copolymer of disulfide-linked polyethylene glycol 5000-lysine-di-tocopherol succinate (P5kSSLV) was designed and synthesized. Thin-film hydration method was used to prepare DOX-loaded P5kSSLV nanomicelle. To optimize the preparation technology, we investigate the effects of dosage, type of organic solvent, hydration temperature and time, and cryoprotectant on drug-loading content, encapsulation efficiency, particle size, and zeta potential. The mean particle size and zeta potential were determined by Zetasizer. The morphology of the P5kSSLV-DOX nanomicelles was visualized by transmission electron microscopy. The drug-loading content and encapsulation efficiency of P5kSSLV-DOX nanomicelle were investigated by UV. The drug-loading content, encapsulation efficiency, particle size, and zeta potential of the final optimized nanomicelles were 4.58%, 97.20%, 30.21 nm and −0.84 mV, respectively. In addition, the stability of nanomicelles was investigated, which included dilution stability and storage stability. The results showed that P5kSSLV-DOX nanomicelle had good dilution stability and storage stability at 4 °C. The preparation method of P5kSSLV-DOX nanomicelle with thin-film hydration method was practical and simple, which was valuable to be further studied.

A novel hollow fiber/graphene oxide/solvent bar microextraction coupled with high performance liquid chromatography for preconcentration and determination of tanshinones and salvianolic acids in Radix Salvia miltiorrhiza

In this paper, a novel hollow fiber/graphene oxide/solvent bar microextraction (HF-GO-SBME) coupled with high-performance liquid chromatography was developed and introduced for simultaneous preconcentration and determination of lipid-soluble active ingredients including dihydrotanshinone I, cryptotanshinone, tanshinone I, and tanshinone IIA, as well as water-soluble salvianolic acid B, danshensu, and protocatechuic aldehyde in Radix Salvia miltiorrhiza. To evaluate the technique, seven compounds of varying polarity were used as model analytes, and a polyvinylidene fluoride hollow fiber of 1.0 cm filled with graphene oxide attached n-octanol was used as a microextraction bar. The extraction conditions, including the amount of graphene oxide, the type and amount of organic solvent, sample phase pH, salt concentration, agitation speed, extraction time, and sample phase volume, were investigated and optimized in detail. The solid–liquid synergistic microextraction mechanism of HF-GO-SBME was analyzed and verified. Under the most favorable conditions, the enrichment factors of the target analytes were 2.4–905, the limits of detection were below 0.92 ng mL−1, and the recoveries were between 84.5% and 107.5%. Thus, HF-GO-SBME is a simple, effective, low-cost, high enhancement factor and practical microextraction mode with a wide range of potential applications for extraction and preconcentration of trace analytes.

Repulsive effect of salt on solvent extraction of 2,3-butanediol from aqueous fermentation solution

BACKGROUND Solvent extraction of 2,3-butanediol from dilute fermented systems is a challenging downstream unit operation. Addition of certain kosmotropic salts to the aqueous fermentation broth during the solvent extraction process can have considerable influence on the distribution of 2,3-butanediol. This work evaluates the usefulness of solvent extraction and the salting-out effect on the extraction characteristic of 2,3-butanediol in aqueous synthetic and fermented solutions. RESULTS Addition of 10 wt% dipotassium phosphate (K2HPO4) to the fermented 2,3-butanediol broth during solvent extraction results in 1.5–3-fold increase in distribution coefficient (Kd) and 7–14-fold increase in separation factor (α) for 2,3-butanediol using 2-sec butyl phenol and 1-butanol as extractants. Of various solvent–salt combinations studied; 2-sec butyl phenol + 10 wt% K2HPO4 provided Kd and α of 3.04 and 59.17 whereas 1-butanol + 10 wt% K2HPO4 provided Kd and α of 2.41 and 15.68, respectively, in fermented 2,3-butanediol broth solution. CONCLUSION This study demonstrated the prospects of repulsive salts addition to the fermented broth during the solvent extraction process. The results showed that this study may be used as a model to choose an appropriate combination of water-immiscible (hydrophobic) organic solvent and inorganic salt type and concentration for the economical recovery of 2,3-butanediol from fermentation broth. © 2014 Society of Chemical Industry

Determination of conditional stability constants for some divalent transition metal ion-EDTA complexes by electrospray ionization mass spectrometry.

Conditional stability constants of coordination complexes comprising divalent transition metals, Cu(2+), Ni(2+), Zn(2+), Co(2+), and ethylenediaminetetraacetic acid (EDTA) were determined utilizing electrospray ionization mass spectrometry. The deviation of signal response of a reference complex was monitored at addition of a second metal ion. The conditional stability constant for the competing metal was then determined through solution equilibria equations. The method showed to be applicable to a system where Co(2+) and Zn(2+) competed for EDTA at pH 5. When Cu(2+) and Ni(2+) competed for EDTA, the equilibrium changed over time. This change was shown to be affected in rate and size by the type of organic solvent added. In this work, 30% of either methanol or acetonitrile was used. It was found that if calibration curves are prepared for both metal complexes in solution and the measurements are repeated with sufficient time space, any change in equilibrium of sample solutions will be discovered.

Effects of selected operational parameters on efficacy and selectivity of electromembrane extraction. Chlorophenols as model analytes.

Effects of organic solvent type, pH value, and composition of donor/acceptor solution on the efficacy of electromembrane extraction (EME) were examined. For the first time, a comprehensive quantitative study, based also on measurements of electric charge passed through the EME system, was carried out, which demonstrates that apart from the pH value, also the nature of counter-ions in donor and acceptor solution plays a significant role in the electrically induced transfer of charged analytes across supported liquid membranes (SLMs). The EME transfer of model analytes correlated well with electrophoretic mobilities of inorganic cations, which were added to acceptor solutions during their alkalization with alkali metal hydroxides, and were highest for counter-cations with highest mobilities. Up to a 53-fold improvement of extraction efficiency was achieved for EMEs using optimized composition of donor (alkalized with KOH to pH 7) and acceptor (10 mM CsOH, pH 12) solutions. Six chlorophenols (CPs) were selected as model analytes due to the wide range of pH values that are required for their ionization and due to their high environmental relevance; quantitative measurements were carried out by CE with UV detection. Extraction recoveries of the six CPs ranged between 14 and 25% for 5 min EMEs at 150 V and 750 rpm across SLMs impregnated with 1-ethyl-2-nitrobenzene. Calibration curves were strictly linear (r(2) ≥ 0.999) in 0.01-10 μg/mL range, repeatability values of peak areas were between 0.7 and 5.6% and LODs for standard solutions and environmental samples were better than 5 ng/mL.

Enantioseparation of N-derivatized amino acids by micro-liquid chromatography using carbamoylated quinidine functionalized monolithic stationary phase

In order to obtain satisfactory column permeability, efficiency and selectivity for micro-HPLC, a capillary monolithic column containing O-9-[2-(methacryloyloxy)-ethylcarbamoyl]-10,11-dihydroquinidine (MQD) as chiral selector was re-optimized. The monolithic column was used to successfully enantioresolve a wide range of N-derivatized amino acids including alanine, leucine, methionine, threonine, phenylalanine, valine, serine, isoleucine, tryptophan, and cysteine. The influence of mobile phase parameters, such as the organic solvent type and concentration, the apparent pH, and buffer concentration, on retention and enantioseparation of N-derivatized amino acids has been investigated. 3,5-dinitrobenzoyl-amino acids and 3,5-dichlorobenzoyl-amino acids were resolved into enantiomers with exceptionally high selectivity and resolution. The chemoselectivity of the monolithic column for a multicomponent mixture of N-derivatized amino acids was also investigated. A mixture of three pairs of 3,5-dichlorobenzoyl-amino acids could be fully resolved in 22.5min.

Enhanced performance of dicationic ionic liquid electrolytes by organic solvents

The use of dicationic ionic liquid (DIL) electrolytes in supercapacitors is impeded by the slow dynamics of DILs, whereas the addition of organic solvents into DIL electrolytes improves ion transport and then enhances the power density of supercapacitors. In this work, the influences of organic solvents on the conductivity of DILs and the electrical double layer (EDL) of DIL-based supercapacitors are investigated using classical molecular dynamics simulation. Two types of organic solvents, acetonitrile (ACN) and propylene carbonate (PC), were used to explore the effects of different organic solvents on the EDL structure and capacitance of DIL/organic solvent-based supercapacitors. Firstly, it was found that the conductivity of DIL electrolytes was greatly enhanced in the presence of the organic solvent ACN. Secondly, a stronger adsorption of PC on graphite results in different EDL structures formed by DIL/ACN and DIL/PC electrolytes. The expulsion of co-ions from EDLs was observed in DIL/organic solvent electrolytes rather than neat DILs and this feature is more evident in DIL/PC. Furthermore, the bell-shaped differential capacitance–electric potential curve was not essentially changed by the presence of organic solvents. Comparing DIL/organic solvent electrolytes with neat DILs, the capacitance is slightly increased by organic solvents, which is in agreement with experimental observation.

Selective Enantioseparation of Racemic Amlodipine by Biphasic Recognition Chiral Separation System

The biphasic recognition chiral extraction process was developed and applied to separate amlodipine enantiomer. The chiral extraction system contained tartaric acid derivatives in the organic phase and β-cyclodextrin derivatives in the aqueous phase. The effect of extraction equilibrium time and the influence of different types of tartaric acids, types of β-cyclodextrin derivatives, organic solvents, and buffer pH were investigated. The results indicated that hydroxypropyl-β-cyclodextrin (HP-β-CD) showed a higher recognition ability toward (S)-amlodipine than (R)-amlodipine while dibenzoyl-D-tartrate demonstrated the strongest ability among tartaric acid derivatives to bind with (R)-amlodipine. The distribution ratios for (S)-amlodipine (kS) and (R)-amlodipine (kR) gave optimum values at pH 5.0 of 16.54 and 0.78, respectively. Biphasic chiral recognition extraction has great significance for preparative separation of (S)-amlodipine. It can also be used to design and apply the enantioseparation process.

Electrochemical Performance of Lithium-Sulfur Cells in Various Organic Electrolyte Solutions

Lithium-ion batteries (LIB) have been widely used as the power source of portable electronic devices, and their application area have been recently expanded to electric vehicles and large-scale storage system. However, current LIB technologies are faced with severe limitations of cost and energy density. For this reason, a number of researchers are trying to find alternative systems to replace lithium-ion batteries. Lithium-sulfur (Li-S) batteries are considered as one of strong candidates due to high theoretical capacity (1675 mAh/g-sulfur) and low cost of active materials. It has been known that the electrochemical reactions of the sulfur cathode are fairly complicated, which consist of several charge transfer reactions and complex chemical reactions. It is commonly accepted that the physicochemical and electrochemical properties of polysulfides and lithium anodes are critically dependent on the type of organic solvent. In result, electrochemical performance of Li-S cells is strongly affected by electrolyte systems. Up to now, however, a few studies on electrolyte systems for Li-S cells have been presented. In this study, comprehensive studies to find a suitable electrolyte solution are presented. Chemical reactivity and stability of polysulfides and lithium metal in a number of organic solvents are systematically investigated, and finally optimal electrolyte systems for Li-S cells are suggested.

Enantioselective extraction of clorprenaline enantiomers with hydrophilic selector of sulfobutylether-β-cyclodextrin by experiment and modeling

Enantioselective extraction of hydrophobic clorprenaline (CPE) enantiomers from organic phase to aqueous phases with sulfobutylether-β-cyclodextrin (SBE-β-CD) as the selector was investigated with insight into a number of important process variables, such as the type of organic solvent, concentration of selector, pH, and temperature. Equilibrium of the extraction system was modeled using a reactive extraction model with a homogeneous aqueous phase reaction. The important parameters of this model were determined experimentally. The physical distribution coefficients for molecular and ionic CPE were determined as 0.3 and 8.93, respectively. The equilibrium constants of the complexation reaction with SBE-β-CD were determined as 152 and 110 L/mol for R- and S-CPE, respectively. Results show that the experimental data agree with the model predictions perfectly. Comprehensively considering the experiment and model, the extraction conditions are optimized and the best extraction conditions are: pH of 6.0, SBE-β-CD concentration of 0.04 mol/L, and temperature of 5 °C, providing the enantioselectivity (α) of 1.25, the fraction of R-CPE (φR) in aqueous phase of 0.71 and performance factor (pf) of 0.025.

Determination of organochlorine pesticide residues in rice by gas chromatography-mass spectrometry following directly suspended droplet microextraction

A simple and efficient approach as directly suspended droplet microextraction (DSDME) was applied to the determination of organochlorine pesticides in rice prior to analysis by gas chromatography-mass spectrometry (GC-MS). The extraction parameters such as organic solvent type and volume, extraction time, and ion strength were systemically optimized. Furthermore, method linearity, recovery, limits of detections (LODs), and precision were also investigated. The proposed method provided good linearity (R2 = 0.9900–0.9996). LODs determined by GC-MS in selected-ion monitoring (SIM) mode were between 0.0005–0.033 mg/kg. The relative standard deviations (RSDs) varied from 2.0–14.0%, while the enrichment factors were between 221–550. The experimental results suggest that DSDME followed by GC-MS is a simple, sensitive, low-cost and little solvent consumption for the determination of organochlorine pesticides in rice, and has high enrichment factors suitable to trace analysis.

One-Step Production of Protein-Loaded PLGA Microparticles via Spray Drying Using 3-Fluid Nozzle

The aim of this study was to investigate the potential of using a spray-dryer equipped with a 3-fluid nozzle to microencapsulate protein drugs into polymeric microparticles. Lysozyme and PLGA were used as a model protein and a model polymer, respectively. The effects of process and formulation variables, such as i) the type of organic solvent, ii) the feeding rate ratio of the outer PLGA-containing feed solution to inner lysozyme-containing feed solution, and iii) the mass ratio of PLGA to protein, on the properties (morphology, internal structure, protein surface enrichment and release profiles) of the spray dried microparticles were investigated to understand protein microencapsulation and particle formation mechanisms. The spherical, condensed microparticles were obtained with D50 of 1.07-1.60μm and Span in the range of 0.82-1.23. The lysozyme surface content decreased upon different organic solvents used as follows: acetonitrile > acetone > dichloromethane. Additionally, the lysozyme surface enrichment decreased slightly when increasing the feeding rate ratio of the outer feed solution to the inner feed solution from 4:1 to 10:1. Furthermore, it was observed that there was a correlation between the degree of burst release and the lysozyme surface enrichment, whereas the lysozyme loading content had no substantial impact on the release kinetics. The present work demonstrates the potential of spray dryer equipped with a 3-fluid nozzle in microencapsulation of proteins into PLGA matrices with different characteristics by varying process and formulation parameters.

Fabrication of porous polymer microparticles with tunable pore size and density through the combination of phase separation and emulsion-solvent evaporation approach

A facile and versatile route to prepare porous polymer microparticles with tunable pore size and density through the combination of phase separation and emulsion-solvent evaporation method is demonstrated. When volatile organic solvent (e.g., chloroform) diffuses through the aqueous phase containing poly(vinyl alcohol) (PVA) and evaporates, n-hexadecane (HD) and polystyrene (PS) in oil-in-water emulsion droplets occur to phase separate due to the incompatibility between PS and HD, ultimately yielding microparticles with porous structures. Interestingly, density of the pores (pore number) on the shell of microparticles can be tailored from one to hundreds by simply varying the HD concentration and/ or the rate of solvent evaporation. Moreover, this versatile approach for preparing porous microparticles with tunable pore size and density can be applied to other types of hydrophobic polymers, organic solvents, and alkanes, which will find potential applications in the fields of pharmaceutical, catalyst carrier, separation, and diagnostics.

Synthesis of nanostructured TiO2 (anatase) and TiO2(B) in ionic liquids

Sol–gel synthesis of TiO2 (anatase) and TiO2(B) was carried out in the presence of imidazolium based ionic liquids with tetrafluoroborate and chloride ions. The prepared nanoparticles were characterized by cyclic voltammetry, Raman spectroscopy and scanning electron microscopy. The influence of organic solvent type and synthesis atmosphere on the product's composition was evaluated. It was established that a nitrogen atmosphere favours the growth of anatase crystalline phase and inhibits the formation of TiO2(B).

Morphology control of amino acid particles in interfacial crystallization using inkjet nozzle

The aim of this study is to apply the inkjet technique to liquid–liquid interfacial crystallization. Instillation with an inkjet nozzle was compared with the batch process in order to evaluate the effectiveness of the inkjet technique for controlling particle morphology. The effects of amino acid solution concentration and organic solvent type on particle properties were investigated for instillation with an inkjet nozzle. The morphology of alanine and glycine particles was observed by scanning electron microscopy and X-ray powder diffraction. The inner structure of alanine and glycine particles was investigated by cutting particles with an ion milling machine. Controlling particle size by adjusting the droplet size in the instillation with an inkjet nozzle was found to be feasible. Most alanine and glycine particles produced by instillation were spherical, whereas most particles produced by the batch process were non-spherical. A higher concentration of amino acid in the solution may lead to the generation of solute particles at the spherical interface. It was found that the surface structure of alanine particles changed when using two kinds of organic solvents as anti-solvents. In addition, instillation allowed for β-glycine to be identified and the crystal polymorph of the particles to be controlled.

HOLLOW FIBER LIQUID PHASE MICROEXTRACTION COMBINED WITH HIGH PERFORMANCE LIQUID CHROMATOGRAPHY FOR PRECONCENTRATION AND DETERMINATION OF CABERGOLINE IN BIOLOGICAL SAMPLES

In this study, a simple and efficient hollow fiber liquid phase microextraction (HF–LPME) method coupled with high performance liquid chromatography has been developed for preconcentration and determination of cabergoline in plasma and urine samples. Cabergoline was extracted from 15 mL of basic sample solution with pH of 10 into an organic extracting solvent (n-octanol) impregnated in the pores of a hollow fiber, and then back-extracted into an acidified aqueous solution in the lumen of the hollow fiber with pH of 3. The extraction was performed due to pH gradient between the inside and outside of the hollow fiber membrane. In order to obtain high extraction efficiency, the parameters affecting the HF–LPME including the type of organic solvent, pH of the donor and acceptor phases, ionic strength, stirring rate, volume ratio of donor to acceptor phase, extraction time, and temperature were studied and optimized. Under the optimized conditions, enrichment factors up to 315 were achieved. The detection limit and relative standard deviation (RSD) (n = 5, c = 2 µg L−1) for cabergoline were 0.01 µg L−1 and 4.5%, respectively. The method was successfully applied to determine the concentration of cabergoline in the plasma and urine samples and satisfactory results were obtained.

The Influence of Temperature and Ethanol Concentration in Monacolin K Extraction from Monascus Fermented Rice

One of the major causes of death is coronary heart disease which is usually caused by hypercholesterolemia. HMG-CoA reductase is a rate-limiting enzyme that plays important role in cholesterol biosynthetis. The enzyme acts a prime target for pharmacology intervention. Monacolin K is known as an inhibitor of HMG-CoA reductase. It was produced as a fungal metabolite either from Monascus sp. or Aspergillus terreus strain. The compound had been proven to be anticholesterol and antihypotensive agent. Red Yeast Rice or angkak is a traditional food that fermented by Monascus sp. Traditional form of angkak resulting specific smell and taste. Extraction of angkak will make a better form with more acceptance by consumer. During extraction process, the type of organic solvent and temperature are critical factor for compound extraction. The aim of this study was to investigate the influence of ethanol concentration and temperature in Monacolin K extraction process from Monascus Fermented Rice (MFR). Investigation of extraction process was carried out using variable of ethanol concentration i.e. 40, 50, 60, 70, 80 and 95% (v/v). The effect of temperature during extraction was also investigated through two condition i.e. room temperature and 60°C. The amount of Monacolin K, which contained in crude extract, was measured using spectrophotometric and High Performance Liquid Chromatography (HPLC) method. The results showed that the highest amount of Monacolin K in crude extract was found in extraction using 95% v/v of ethanol (MFR95) whereas effect of heating procedure also showed that the amount of Monacolin K in crude extract was increased in 60°C. HPLC analysis showed that the yield of Monacolin K in crude of MFR95 extract was 1760μg g-1. In conclusion, ethanol 95% v/v and heated in 60°C were the best choice for extraction of Monacolin K from MFR.

Determination of Aroma Components in Chinese Southwest Tobacco by Directly Suspended Droplet Microextraction Combined with GC–MS

In this paper, a simple and efficient approach, directly suspended droplet microextraction (DSDME), has been applied to extract aroma components in Chinese southwest tobacco prior to analysis by gas chromatography-mass spectrometry (GC-MS). The extraction parameters such as organic solvent type, extraction time, temperature, stirring speed and volume were systemically optimized. A single drop of cyclohexane was placed on the top of the aqueous sample which was used as solvent. Under the optimal conditions of DSDME, 62 aroma components of tobacco were analyzed and identified by GC-MS. The approach was used to determine some important aromas in tobacco with the relative recoveries ranged from 75.92 to 102.88%, relative standard deviations in the range of 3.40-7.14% (n = 5) and the limits of detection of 0.0002-0.002 μg/mL. Moreover, the DSDME was applied to identify the aromatic components in Chinese southwest tobacco in this research for the first time and the results suggested that the method can be used as rapid determination of the tobacco. This method can enhance the extracting rate of tobacco aromatic components and meet the need of qualitative analysis of large amount samples.

Experimental and Model Study on Enantioselective Reactive Extraction of 2-chlorophenylglycine Enantiomers with BINAP-Metal Complexes

Equilibrium study on enantionselective extraction of 2-chlorophenylglycine (CPG) enantiomers with S-BINAP-metal complexes as selector was performed. A reactive extraction model with an interfacial reaction of CPG enantiomers with S-BINAP-metal complex was established. The extraction system shows good selectivity towards CPG enantiomers. [(S-BINAP)Cu(CH3CN)][PF6] (BINAP-Cu) exhibits the highest selectivity among the selectors studied. Efficiency of the extraction depends, often strongly, on a number of process variables, including types of organic solvents and metal precursors, concentration of the selector, the pH, and the temperature. The model quantitatively predicts extraction performance as a function of key operating parameters, providing a simple computational approach to process optimization. High enantioselectivity of 3.01 was obtained.

Studies on Enantioselective Liquid–Liquid Extraction of Amino‐(4‐nitro‐phenyl)‐acetic Acid Enantiomers: Modeling and Optimization

BINAP-metal complexes were prepared as extractant for enantioselective liquid-liquid extraction (ELLE) of amino-(4-nitro-phenyl)-acetic acid (NPA) enantiomers. The influence of process variables, including types of organic solvents and metal precursor, concentration of ligand, pH, and temperature on the efficiency of the extraction, were investigated experimentally. An interfacial reaction model was established for insightful understanding of the chiral extraction process. Important parameters required for the model were determined. The experimental data were compared with model predictions to verify the model prediction, It was found that the interfacial reaction model predicted the experimental results accurately. By modeling and experiment, an optimal extraction condition with pH of 7 and host (extractant) concentration of 1 mmol/L was obtained and high enantioselectivity (αop ) of 3.86 and performance factor (pf) of 0.1949 were achieved.