Water-insoluble Organic Solvents Research Articles

Pentafluoropropionic Anhydride Derivatization and GC-MS Analysis of Histamine, Agmatine, Putrescine, and Spermidine: Effects of Solvents and Starting Column Temperature.

Gas chromatography-mass spectrometry (GC-MS) is useful for the quantitative determination of the polyamines spermidine (SPD) and putrescine (PUT) and of the biogenic amine agmatine (AGM) in biological samples after derivatization. This GC-MS method involves a two-step extraction with n-butanol and hydrochloric acid, derivatization with pentafluoropropionic anhydride (PFPA) in ethyl acetate, and extraction of the pentafluoropropionic (PFP) derivatives by toluene of SPD, PUT, and AGM. We wanted to extend this GC-MS method for the biogenic amine histamine (HA), but we faced serious problems that did not allow reliable quantitative analysis of HA. In the present work, we addressed this issue and investigated the derivatization of HA and the effects of toluene and ethyl acetate, two commonly used water-insoluble organic solvents in GC-MS, and oven temperature program. Derivatization of unlabelled HA (d0-HA) and deuterium-labelled HA (d4-HA) with PFPA in ethyl acetate (PFPA-EA, 1:4, v/v; 30 min, 65 °C) resulted in the formation of d0-HA-(PFP)2 and d4-HA-(PFP)2 derivatives. d4-HA and 13C4-SPD were used as internal standards for the amines after standardization. Considerable quantitative effects of toluene and ethyl acetate were observed. The starting GC column temperature was also found to influence considerably the GC-MS analysis of HA. Our study shows the simultaneous quantitative analysis of HA as HA-(PFP)2, AGM as AGM-(PFP)3, PUT as PUT-(PFP)2, and SPD as SPD-(PFP)3 derivatives requires the use of ethyl acetate for their extraction and injection into the GC-MS apparatus and a starting GC column temperature of 40 °C instead of 70 °C. The PFP derivatives of HA, AGM, PUT, and SPD were found to be stable in ethyl acetate for several hours at room temperature. Analytically satisfactory linearity, precision, and accuracy were observed for HA, AGM, PUT, and SPD in biologically relevant ranges (0 to 700 pmol). The limits of detection of AGM, PUT, and SPD were about two times lower in ethyl acetate compared to toluene (range, 1-22 fmol). The limits of detection were 1670 fmol for d0-HA and 557 fmol for d4-HA. Despite the improvements achieved in the study for HA, its analysis by GC-MS as a PFP derivative is challenging and less efficient than that of PUT, AGM, and SPD.

Molecular and biochemical characterization of a recombinant endoglucanase rCKT3eng, from an extreme halophilic Haloarcula sp. strain CKT3

Halophilic cellulases are indispensable enzymes of heavy industrial processes as resistant biocatalysts due to high level activity at extreme conditions. In this study, crude cellulase from an extreme halophilic Haloarcula sp. CKT3 was characterized. Then, recombinant expression of putative endo-1,4-β-glucanase gene, of CKT3 strain, in E. coli BL21(DE3) was performed with the aim of obtaining highly pure, active and robust industrial enzyme for such industrial aplications. The crude cellulase had optimal activity (16.9 U/mg) at 70 °C, pH 7.0 and 4 M NaCl exhibiting good thermostability, high pH and halotolerance. Indeed, it is very stable in water-insoluble organic solvents with log Po/w ≥ 2.13 and highly resistant to SDS (10%). Recombinant CKT3eng has a molecular weight of 36.9 kDa and 99% aminoacid identity to endo-l,4-β-D-glucanase from Haloarcula argentinensis. Its 3D structure was predicted using Phyre2 and I-TASSER. rCKT3eng enzyme provided 31.6 U/mg activity at optimal 50 °C, pH 7.0 and 3 M NaCl. In addition to its quite similar stability values and resistance to organic solvents and SDS, rCKT3eng has superiority over crude enzyme with 1.87-fold higher specific activity. Therefore, rCKT3eng offers a promising enzyme for industrial use with its valuable activity and stability in extreme conditions.

PG-PEI-Ag NPs-Decorated Membrane for Pretreatment of Laboratory Wastewater: Simultaneous Removal of Water-Insoluble Organic Solvents and Water-Soluble Anionic Organic Pollutants.

Generally, waste liquid in laboratory can be roughly classified into organic wastewater and inorganic wastewater. However, in some experiments, organic phase and water phase are inevitably mixed together, leaving the postclassification and disposal intractable. Traditionally, we used methods like distillation and extraction to separate these two phases, however, always consuming significant amounts of labor and time and meanwhile having an unsatisfactory separation efficiency. Here, we proposed an improved processing method with a propyl gallate (PG)-polyethyleneimine (PEI)-Ag nanoparticles (NPs)-decorated membrane, possessing the special wettability designed for organic and water phase separation. Accordingly, various kinds of organic solvents/water mixtures were tested, where the PG-PEI-Ag NPs-decorated membrane was used like a common filter paper, fixed onto the funnel of the waste liquid barrel. Afterward, the two phase mixtures were poured onto the membrane; as a result, the organic phase was blocked above while the water phase was left below. All kinds of organic solvents/water mixtures showed higher than 99.90% removal efficiency. Besides, the membrane can remove water-soluble anionic organic molecules through electrostatic interaction. Thus, along the phase separation, anionic organic molecules in water can be removed simultaneously. This pretreatment of lab wastewater with the PG-PEI-Ag NPs-decorated membrane is simple and efficient, relieving the pressure of postcollection and disposal to some extent.

Facile synthesis of flexible mesoporous aerogel with superhydrophobicity for efficient removal of layered and emulsified oil from water

Aerogel with porous structure and ultra-light weight is a potential sorbent for solving oils or organic solvents pollution. Herein, a type of flexible mesoporous aerogel was fabricated though a simple ambient pressure drying using methyltrimethoxysilane/dodecyltrimethoxysilane (MTMS/DTMS) as precursors and distilled water as solvent. The as-synthesized aerogel exhibits superhydrophobicity with water contact angle of 163° and low density of 0.102 g/cm3. Moreover, the aerogel can selectively separate oils and water-insoluble organic solvents on and under water, and the sorption capacities can reach up to 7.98–13.4 times its own weight. More importantly, the obtained aerogel is capable of separate surfactant-free and surfactant-stabilized oil-in-water emulsions with high separation efficiency of greater than 98.4%. In addition, the aerogel is highly resistant toward corrosive aqueous solutions (acidic, alkaline, salty solutions), harsh temperature environments (−30 and 160 °C), and mechanical abrasion. Due to eco-friendly fabrication process, low cost, and outstanding oil/water separation performance, the developed aerogel have potential application in oils or organic pollutants sorption and water purification.

Emulsion Hydrogel Soft Motor Actuated by Thermal Stimulation.

An emulsion hydrogel motor (E-H motor), constituted by low-boiling-point oil fuel and a hydrogel matrix, is prepared through a simple yet versatile oil-in-water (O/W) emulsion template method. The E-H motor can be efficiently propelled by the bubbles generated under a thermal stimulus. As thermally induced explosion occurs inside the E-H motor (diameter ∼4.0 mm and length ∼6.0 mm), the gas bubbles resulting from thermotropic phase transition are violently ejected from one side, leading to a fast speed of 14.78 ± 4.82 mm s-1 in a 60 °C aqueous solution. Additionally, multiple water-insoluble organic solvents can serve as the fuel for self-propulsion, which demonstrates the favorable universality of the E-H motor. The magnetic navigation and near-infrared propulsion can be realized through incorporating hydrophilic iron oxide (Fe3O4) nanoparticles and graphene oxide (GO) into the aqueous phase. Moreover, the synchronous integration of GO and enrofloxacin bactericide can enable intelligent targeted cargo transportation and delivery. The attractive self-propulsion performance, precise locomotion control, and formidable integration ability of the emulsion hydrogel-based miniaturized soft motor hold great promise for numerous practical applications.

Calotropis gigantea fiber derived carbon fiber enables fast and efficient absorption of oils and organic solvents

Abstract Here, we report a facile pyrolysis process to obtain an eco-friendly and sustainable oil-absorbing material by using a green plant fiber, i.e. Calotropis gigantea fiber with hollow tubular structure, as the starting raw material. The resulting carbon fiber keeps still the hollow structure in spite of shrinking size in diameter and curling edge in shape. When used as an absorbent, this carbon fiber can effectively and rapidly absorb a variety of model oils (including water-insoluble organic solvents), with the oil-absorbing capacity of up to 130 g/g within a few seconds. During the pyrolysis process, the pyrolysis temperature has a profound effect on the oil-absorbing capacity, while such a property is not greatly affected by the pyrolysis time. Further study implies that the carbon fiber can be well recovered by extracting with absolute ethanol to yield the full release of model oils (∼100%), and then reused for more than 10 cycles. Given its good hydrophobicity, high oil-absorbing capacity, good recyclability, and sustainable characteristics, such a hollow carbon fiber shows its potential applications as an efficient and sustainable oil-absorbing material for the removal and recovery of different oils in industry for environmental protection.

Production and Characterization of Organic Solvent-Tolerant Cellulase from Bacillus amyloliquefaciens AK9 Isolated from Hot Spring.

A cellulase-producing bacterium, designated as strain AK9, was isolated from a hot spring of Tatta Pani, Azad Kashmir, Pakistan. The bacterium was identified as Bacillus amyloliquefaciens through 16S rRNA sequencing. Cellulase from strain AK9 was able to liberate glucose from soluble cellulose and carboxymethyl cellulose (CMC). Enzyme was purified through size exclusion chromatography and a single band of ∼47kDa was observed on sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). The enzyme was purified with recovery of 35.5%, 3.6-fold purity with specific activity of 31Umg-1. The purified cellulase retained its activity over a wide range of temperature (50-70°C) and pH (3-7) with maximum stability at 60°C and pH5.0. The activity inhibited by ethylenediaminetetraacetic acid (EDTA), suggested that it was metalloenzyme. Diethyl pyrocarbonate (DEPC) and β-mercaptoethanol significantly inhibited cellulase activity that revealed the essentiality of histidine residues and disulfide bonds for its catalytic function. It was stable in non-ionic surfactants, in the presence of various metal ions, and in water-insoluble organic solvents. Approximately 9.1% of reducing sugar was released after enzymatic saccharification of DAP-pretreated agro-residue, compared to a very low percentage by autohydrolysis treatment. Hence, it is concluded that cellulase from B. amyloliquefaciens AK9 can potentially be used in bioconversion of lignocellulosic biomass to fermentable sugars.

Purification and characterization of an organic-solvent-tolerant cellulase from a halotolerant isolate, Bacillus sp. L1

A halotolerant isolate Bacillus sp. L1 producing extracellular cellulase was isolated from Yuncheng, China. Production of the enzyme started from mid-exponential phase of bacterial growth and reached a maximum level during the post-stationary phase. The cellulase was purified to homogeneity with molecular mass of 45 kDa. Substrate specificity test indicated that it was an endoglucanase for soluble cellulose. Optimal enzyme activity was found to be at 60 °C, pH 8.0, and 7.5 % NaCl. Furthermore, it was highly active and stable over broad ranges of temperature (30-80 °C), pH (7.0-9.0), and NaCl concentration (2.5-15 %), thus showing its excellent thermostable, alkali-stable, and halotolerant nature. The cellulase activity was greatly inhibited by ethylenediaminetetraacetic acid, indicating that it was a metalloenzyme. Significant inhibition by phenylmethylsulfonyl fluoride and phenylarsine oxide revealed that serine and cysteine residues were essential for the enzyme catalysis. Moreover, the cellulase was highly active in the presence of surfactants, and it showed high stability in the presence of water-insoluble organic solvents with log P (ow)at least 0.88. Results from this study indicate that the purified cellulase from isolate L1 may have considerable potential for industrial application owing to its useful properties.

Morphology and electrochemical properties of amphiphilic viologen functionalized multiwalled carbon nanotube hybrids in Langmuir–Blodgett films

Amphiphilic viologens were electrostatically adsorbed on the surface of multiwalled carbon nanotubes (MWCNT) to form viologen–MWCNT hybrids, in which the content of viologens was about 5–10% in weight. Although both viologens and MWCNT hardly dispersed in the water-insoluble organic solvents, the as-prepared viologen–MWCNT hybrids were well dispersed in them with a strong long-term stability, the features of which provided a possibility to prepare their insoluble monolayers at the air–water interface. The surface pressure–area isotherms of these hybrids revealed that they could form stable monolayers, which were transferred on the substrate surfaces by the Langmuir–Blodgett (LB) method. Morphologies of the LB films were characterized by using scanning electron microscopy and atomic force microscopy, the images of which revealed the formation of network two- or three-dimensional films of the functionalized MWCNT. Cyclic voltammograms of the LB films revealed one or two couples of one electron transfer process corresponding to the viologen–MWCNT hybrids with the cathodic and anodic potentials closely related to the alkyl chains of the viologens.

Characterization of an organic solvent-tolerant α-amylase from a halophilic isolate, Thalassobacillus sp. LY18

A halophilic isolate Thalassobacillus sp. LY18 producing extracellular amylase was isolated from the saline soil of Yuncheng Salt Lake, China. Production of the enzyme was synchronized with bacterial growth and reached a maximum level during the early stationary phase. The amylase was purified to homogeneity with a molecular mass of 31 kDa. Major products of soluble starch hydrolysis were maltose and maltotriose, indicating an α-amylase activity. Optimal enzyme activity was found to be at 70°C, pH 9.0, and 10 % NaCl. The α-amylase was highly stable over broad temperature (30-90°C), pH (6.0-12.0), and NaCl concentration (0-20 %) ranges, showing excellent thermostable, alkalistable, and halotolerant nature. The enzyme was stimulated by Ca(2+), but greatly inhibited by EDTA, indicating it was a metalloenzyme. Complete inhibition by diethyl pyrocarbonate and β-mercaptoethanol revealed that histidine residue and disulfide bond were essential for enzyme catalysis. The surfactants tested had no significant effects on the amylase activity. Furthermore, it showed high activity and stability in the presence of water-insoluble organic solvents with log P (ow) ≥ 2.13.

Purification and characterization of an organic solvent-tolerant alkaline cellulase from a halophilic isolate of Thalassobacillus

An extracellular cellulase from Thalassobacillus sp. LY18 was purified 4.5-fold with a recovery of 21 % and a specific activity of 52.4 U mg(-1) protein. Its molecular mass was 61 kDa estimated by SDS-PAGE. It was an endoglucanase for soluble cellulose with optimal activity was at 60 °C and pH 8 with 10 % (w/v) NaCl. It was stable from 30 to 80 °C and from pH 7 to 11 with NaCl from 5 to 17.5 % (w/v). EDTA inhibited activity indicating it was a metalloenzyme. Inhibition by diethyl pyrocarbonate and β-mercaptoethanol suggested that histidine residues and disulfide bonds may play important roles in its catalytic function. The cellulase was highly active in non-ionic surfactants and was stable in water-insoluble organic solvents with log P (ow) ≥ 2.13.

Purification and some properties of low-molecular-weight extreme halophilic xylanase from Chromohalobacter sp. TPSV 101

Abstract An extreme halophilic xylanase was purified from cultures of Chromohalobacter sp. TPSV 101 by ultrafiltration, hydroxylapatite and gel filtration chromatography. SDS-PAGE of the xylanase showed an apparent homogeneity and molecular weight of 15 kDa. The xylanase had maximum activity at pH 9.0 and 65 °C in the presence of 15–25% NaCl and was stable in the range of pH 7.0–9.0, temperature between 50 and 70 °C. The enzyme was stable at 50–65 °C for 1 h retaining 100% activity and by retaining 60% activity at 80 °C. The xylanase was completely inhibited by Hg 2+ ions and was partially inhibited by Ca 2+ , Cu 2+ and Pb 2+ ions, whereas Zn 2+ , Mn 2+ and Co 2+ ions enhanced its activity. Both EGTA and EDTA enhanced its activity. It was active in solutions containing water-insoluble organic solvents and osmolytes. Kinetic experiments indicated that the enzyme had K m and V max values of 0.2 mg/ml and 1. 17 μmol/ml/min for oat spelt xylan. The major products of the oat spelt xylan hydrolysis were xylose and xylobiose; after prolonged incubation xylose was the major end product.

Electrochemical Assay of Methyl Parathion in Homogeneous Reaction Using Water Soluble Films with Immobilized Acetylcholinesterase

Water soluble poly (vinyl alcohol) (PVA) was used to prepare the enzyme membranes of acetylcholinesterase (AChE) for electrochemical assaying methyl parathion in water insoluble organic solvent. The immobilized enzyme was separated from electrode for the development of enzyme inhibition-based bioassays. This assay is simple and convenient where enzyme membrane is applicable for single use and the electrode for repeated use. The enzyme membranes can be used handily piece by piece and the released AChE performs catalytic reaction homogeneously. The inhibition percentage of AChE increases with the concentration of methyl parathion ranging from 0.1 to 1 mg/mL.

Interfacial-Force-Controlled Placing Technique of Microstructures of Sub- to One Hundred Micrometer Size Using Blade Coating

The surface mounting technology of electronic devices using pick-and-place machines is commonly used to fabricate functional electronic appliances, such as motherboards, flat panel displays, and mobile phones. However, the pick-and-place method begins to encounter difficulties in mounting electronic devices when devices shrink to a few hundreds of micrometers or less. We propose a new blade-coating method of placing microstructures smaller than several hundreds of micrometers on a substrate. The method comprises three steps: (1) preparing a microstructure dispersion consisting of chemically modified microstructures and a water-insoluble organic solvent, (2) continuous blade-coating of water and the dispersion on a chemically patterned substrate on which hydrophilic areas are surrounded by a hydrophobic self-assembled monolayer, and (3) spontaneous placing of the microstructures on the hydrophilic areas by a water/solvent interfacial force that acts on the microstructures. Using this method, we have been able to place microstructures ranging in length from submicrometer to one hundred micrometers, including silicon nanowires and SiO2 microstructures of various sizes. However, our blade-coating method for placing microstructures can be realized with successful combinations of chemical modifiers for the microstructures and water-insoluble solvents. We present a simple method of assessing dispersion using a chemically modified glass test tube filled with water and a solvent for the dispersion.

Interfacial-Force-Controlled Placing Technique of Microstructures of Sub- to One Hundred Micrometer Size Using Blade Coating

The surface mounting technology of electronic devices using pick-and-place machines is commonly used to fabricate functional electronic appliances, such as motherboards, flat panel displays, and mobile phones. However, the pick-and-place method begins to encounter difficulties in mounting electronic devices when devices shrink to a few hundreds of micrometers or less. We propose a new blade-coating method of placing microstructures smaller than several hundreds of micrometers on a substrate. The method comprises three steps: (1) preparing a microstructure dispersion consisting of chemically modified microstructures and a water-insoluble organic solvent, (2) continuous blade-coating of water and the dispersion on a chemically patterned substrate on which hydrophilic areas are surrounded by a hydrophobic self-assembled monolayer, and (3) spontaneous placing of the microstructures on the hydrophilic areas by a water/solvent interfacial force that acts on the microstructures. Using this method, we have been able to place microstructures ranging in length from submicrometer to one hundred micrometers, including silicon nanowires and SiO2 microstructures of various sizes. However, our blade-coating method for placing microstructures can be realized with successful combinations of chemical modifiers for the microstructures and water-insoluble solvents. We present a simple method of assessing dispersion using a chemically modified glass test tube filled with water and a solvent for the dispersion.

Hydrogen peroxide synthesis by direct photoreduction of 2-ethylanthraquinone in aerated solutions

A new synthesis method of hydrogen peroxide was investigated by the photoreduction of 2-ethylanthraquinone (AQ) in water-insoluble organic solvents. Through optimizing the photoreduction condition including solvent, atmosphere and irradiated time, the photolysis system of 1,3,5-trimethylbenzene/trioctyl phosphate (3:1) solvent mixture under oxygen atmosphere was found to give a high yield of hydrogen peroxide. Furthermore, the formation mechanism of hydrogen peroxide was proposed, i.e. photoreduction and subsequent oxidation of AQ. The photoreduction of 2-ethylanthraquinone undergoes the hydrogen abstraction from solvent to form the anthrahydroquinone, which is subsequently oxidized by oxygen to give hydrogen peroxide.

Enantioselective Hydrogenation in Water Over Chiral Modified Heterogeneous Catalyst Admixed With Organic Solvent

Hydrogenation of α,β-unsaturated acid over cinchonidine-modified Pd/C results in poor enantioselectivity in water, but the selectivity becomes much higher when Pd/C is admixed with a small amount of a hydrophobic water-insoluble organic solvent. With the admixed catalyst, the product is easily removed by separation of the aqueous phase under the hydrogen atmosphere and the remaining catalyst can be reused.

Activity of Phospholipase C in Two-Phase Systems

Although phospholipase C (PLC) is known to be activated by water-insoluble organic solvents, most activity assays have been designed to work in an aqueous milieu. Here a sensitive method is described for the determination of PLC activity in two-phase systems. The assay is based on the hydrolysis of phosphatidylcholine (PC) in chloroform/buffer. The initial rates of the reaction are determined by densitometric quantification of the product 1,2-diacylglycerol after its separation by high-performance TLC and staining with a CuSO4/H3PO4 or p-methoxybenzaldehyde/H2SO4 reagent. The method is examined for the determination of Vmax and Km values of PCs with varying length acyl chains (C10–C18). The comparison of the kinetic parameters with the Vmax and Km values of the same substrates in the conventional titrimetric assay, using sodium deoxycholate for micellization of PC, demonstrates the high efficiency of PLC in the two-phase emulsion system.

The Cytotoxicity of Some Organic Solvents on Isolated Hepatocytes in Monolayer Culture

The cytotoxic effects of volatile and water-insoluble organic solvents (ethylbenzene, tetrachloroethylene, n-hexane) were tested on isolated hepatocytes in monolayer culture by using the 3-(4,5 dimethylthiazol-2-yl)-2,5 diphenyltetrazolium bromide (MTT) reduction assay. All of the tested compounds inhibited metabolic activity of hepatocytes and this effect depended on the concentration of solvents in the incubatory medium. The presence of fetal calf serum in the medium did not change the cytotoxicity of xenobiotics. IC50 values calculated on the basis of the MTT assay indicated that ethylbenzene was more cytotoxic than tetrachloroethylene and n-hexane. Using hepatocyte monolayer culture and the MTT assay to assess cytotoxicity of organic solvents causes many technical problems. It seems that it cannot be used as a rapid, cheap, and credible method.

Equilibrium swelling of colloidal polymeric particles with water-insoluble organic solvents

The Morton–Kaizerman–Altier (MKA) equation fails to describe experimental swelling data of polystyrene particles with toluene in the absence of free or adsorbed surfactants. A modification of the MKA equation is possible by the consideration of a volume work leading to a swelling pressure in analogy to macroscopic gels. With the modified equation a satisfactory description of the experimental data is possible if a size dependence of all the three interaction parameter of the particles with the swelling agent, the swelling pressure, and the interfacial tension of the particles is considered. In the case of particles with diameters below 50 nm and with high surface charge densities an additional electrostatic repulsion contributes to the volume increase during swelling, which is not yet considered in the theory.