Organic Extraction Phase Research Articles

Improvement in Determination of Methylmercury in Sediments by Headspace Trap Gas Chromatography and Atomic Fluorescence Spectrometry after Organic Extraction and Aqueous Phase Ethylation

An automated method for determination of methylmercury in sediments was developed using headspace coupled to gas chromatography with atomic fluorescence spectrometry detection and aqueous phase ethylation. The method avoids the problems associated with purge and trap techniques. The volume of ethylating agent was optimized and headspace only or headspace trap modes were evaluated. The results showed that the latter mode provided better performance for methylmercury determination than the former. An organic extraction of methylmercury from sediment samples was used involving the use of copper(II) sulfate, potassium bromide, and sulfuric acid. The method was verified by analysis of sediment reference materials (IAEA-405; IAEA-433) and the results were in good agreement with certified values. Due to the low detection limit, the method is appropriate for analysis of contaminated and uncontaminated sediment samples at ultratrace levels.

Identification and Analysis of the Pigment Composition and Sources in the Colored Cocoon of the Silkworm,Bombyx mori, by HPLC-DAD

This study used the larval tissues and colored cocoons of silkworms, Bombyx mori L. (Lepidoptera: Bombycidae), that were fed leaves of cultivated mulberry, Husang 32, as experimental material. The pigment composition and content in colored cocoons and tissues of the 5th instar larvae and the mulberry leaves were rapidly detected using organic solvent extraction and reverse phase high-performance liquid chromatography with diode array detection. It was found that the mulberry leaf mainly contained four types of pigment: lutein (30.86%), β-carotene (26.3%), chlorophyll a (24.62%), and chlorophyll b (18.21%). The silk glands, blood, and cocoon shells of six yellow-red cocoons were used as the experimental materials. The results showed that there were generally two kinds of carotenoids (lutein and β-carotene) in the silk gland and cocoon shell, a little violaxanthin was detected in silk gland, and the pigment found in the blood was mainly lutein in all varieties of silkworm tested. Chlorophyll a and b had not been digested and utilized in the yellow-red series of silkworm. The method used to detect visible pigments reported here could be used to breed new colors of cocoons and to develop and utilize the pigments found in mulberry.

Identification and analysis of the pigment composition and sources in the colored cocoon of the silkworm, Bombyx mori, by HPLC-DAD.

This study used the larval tissues and colored cocoons of silkworms, Bombyx mori L. (Lepidoptera: Bombycidae), that were fed leaves of cultivated mulberry, Husang 32, as experimental material. The pigment composition and content in colored cocoons and tissues of the 5th instar larvae and the mulberry leaves were rapidly detected using organic solvent extraction and reverse phase high-performance liquid chromatography with diode array detection. It was found that the mulberry leaf mainly contained four types of pigment: lutein (30.86%), β -carotene (26.3%), chlorophyll a (24.62%), and chlorophyll b (18.21%). The silk glands, blood, and cocoon shells of six yellow-red cocoons were used as the experimental materials. The results showed that there were generally two kinds of carotenoids (lutein and β -carotene) in the silk gland and cocoon shell, a little violaxanthin was detected in silk gland, and the pigment found in the blood was mainly lutein in all varieties of silkworm tested. Chlorophyll a and b had not been digested and utilized in the yellow-red series of silkworm. The method used to detect visible pigments reported here could be used to breed new colors of cocoons and to develop and utilize the pigments found in mulberry.

Synergistic Extraction of Dysprosium and Aggregate Formation in Solvent Extraction Systems Combining TBP and HDBP

During treatment of nuclear fuel in the Plutonium/URanium EXtraction (PUREX) process, the extractant tri-n-butyl phosphate (TBP) is known to degrade to dibutylphosphoric acid (HDBP), which increases the extraction of metal ions, thereby inhibiting their stripping from the organic phase. To better understand this phenomenon, we investigated how mixtures of TBP and HDBP influenced the extraction of metal, nitric acid, and water, and correlated the results to aggregated structures in the organic phase. The mole ratios of TBP-HDBP mixtures had a non-linear effect on the extraction of Dy3+ and water from 0.2 M HNO3, indicating synergism. In 2 M HNO3, the TBP:HDBP mole ratio had a more linear relation to Dy3+ and water extraction, so the synergistic effect was less pronounced than in the low acid system. The extraction of nitric acid showed no synergistic effect and follows closely what would be expected in a system using TBP only. The small-angle X-ray scattering (SAXS) data of the 0.2 M acid system showed maximum contrast at a TBP:HDBP mole ratio of 0.25, so that the synergistic mixture is also the most aggregated at 0.2 M acid. The 2 M acid system also showed that the mixed system is more aggregated than the end members, although this does not result in peak extraction. Previous studies of synergistic extraction of metal cations explain the enhanced extraction by increased dehydration of the metal ion. Although our data do not rule out the formation of mixed complexes according to the classical mechanism of synergism, our evidence of increased water extraction and aggregate formation in systems combining TBP and HDBP are complementary to the metal-centric dehydration aspects of the process. The findings in this study give insights into the complex chemistry of solvent extraction, providing a possible link between formation of aggregates in the organic phase and synergistic extraction.

A new ionic liquid–water–organic solvent three phase microextraction for simultaneous preconcentration flavonoids and anthraquinones from traditional Chinese prescription

A novel technique, ionic liquid–water–organic solvent three phase microextraction (ILWOS-3p-ME) was developed and introduced for simultaneous preconcentration and determination of flavonoids and anthraquinones in Chinese herbal formula and its preparations. This technique was performed in one step by using a syringe. High performance liquid chromatography with an UV-detector (HPLC/UV) was subsequently conducted. Two solvents with different densities (organic solvent and ionic liquid with densities less than and higher than water, respectively) were separately placed in a syringe, which was used as an extraction device. A cloudy emulsion was formed by manually shaking the syringe. The mixture was allowed to stand for several minutes; afterward, the emulsion readily separated into three phases: an upper organic solvent extraction phase; a middle aqueous sample phase; and a lower ionic liquid extraction phase. Both the upper and lower layers were transferred to a small Eppendorf (EP) tube. Conducting ILWOS-3P-ME with HPLC/UV, we simultaneously determined the bioactive components of flavonoids and anthraquinones in traditional Chinese medicine. ILWOS-3P-ME is a simple, rapid, practical, and effective method to extract and preconcentrate of different types of trace bioactive components from traditional Chinese medicine simultaneously.

A conically fixed position single drop microextraction method for isolation of aryloxyphenoxypropionate herbicides from aquatic media

A new and convenient format of single drop microextraction (SDME) was developed and applied for isolation of some selected aryloxyphenoxypropionate herbicides from aquatic media. In contrast to the conventional SDME procedure, in this set-up the extraction microdrop was positioned at the bottom of a conical vial in order to provide much higher stability for the organic extraction phase while a magnetic bar was used for stirring the aqueous solution. A simple magnet was used for positioning the bar on the top of the microdrop prior to stirring. The whole set-up led to the use of any volume of extraction solvent with unlimited stirring rates. Some important extraction parameters such as the type of solvent, stirring rate, temperature and extraction time were investigated and optimized. Selection of a microdrop volume of 3 μL with a sampling time of 35 min along with the use of carbon tetrachloride as the most appropriate solvent led to the highest enrichment factors. The linearity was studied by preconcentration of 1 mL of water samples spiked with a standard solution of aryloxyphenoxypropionates in the concentration range of 0.1–300 μg L−1. The coefficient of determination was satisfactory (r2 > 0.99) for all the studied analytes and the relative standard deviation (RSD%) values under the optimized conditions were found to be in the range of 5.1 to 10.1% at the concentrations of 0.6 and 50 μg L−1. Detection limits were obtained to be in the range of 0.02–0.05 μg L−1 using time-scheduled selected ion monitoring (SIM). The developed method was successfully applied for the extraction and determination of aryloxyphenoxypropionates in river water samples.

Emulsification liquid phase microextraction followed by on-line phase separation coupled to high performance liquid chromatography

An emulsification liquid phase microextraction followed by on-line phase separation coupled to high performance liquid chromatography (HPLC) is introduced based on a novel idea for the separation of dispersed organic phase from aqueous phase. In this method, the dispersed organic extraction phase was filtered using an in-line filter and it was separated from the water sample. The new approach is simple and, in addition to improving some limitations of the conventional emulsification liquid phase microextraction, eliminates the need for centrifugation in the phase separation step.To demonstrate the applicability of the method, it was applied for the extraction and determination of trace amounts of selected parabens as model analytes. In this procedure, 30μL of 1-octanol was injected slowly into 10mL of the aqueous sample inside the ultrasonic water bath. Then, the emulsion formed was passed through the in-line filter located in the loop of the HPLC valve and the organic extraction phase was separated and it was retained in the filter. By changing the position of the valve, the filter was located in the mobile phase pass and the retained organic phase was eluted and transferred to the separation column. The effects of some important parameters such as types of extraction solvent and its volume, ionic strength, and ultrasonication time on extraction efficiency were investigated and optimized. Under optimal conditions, preconcentration factors and limits of detection for the compounds studied were obtained in the ranges of 289–595 and 0.05–0.2μgL−1, respectively. Finally, the method was successfully applied to determine selected parabens in some water and cosmetic samples.

Quantifying the CDK inhibitor VMY-1-103’s activity and tissue levels in an in vivo tumor model by LC-MS/MS and by MRI

The development of new small molecule-based therapeutic drugs requires accurate quantification of drug bioavailability, biological activity and treatment efficacy. Rapidly measuring these endpoints is often hampered by the lack of efficient assay platforms with high sensitivity and specificity. Using an in vivo model system, we report a simple and sensitive liquid chromatography-tandem mass spectrometry assay to quantify the bioavailability of a recently developed novel cyclin-dependent kinase inhibitor VMY-1-103, a purvalanol B-based analog whose biological activity is enhanced via dansylation. We developed a rapid organic phase extraction technique and validated wide and functional VMY-1-103 distribution in various mouse tissues, consistent with its enhanced potency previously observed in a variety of human cancer cell lines. More importantly, in vivo MRI and single voxel proton MR-Spectroscopy further established that VMY-1-103 inhibited disease progression and affected key metabolites in a mouse model of hedgehog-driven medulloblastoma.

Room temperature ionic liquids enhanced the speciation of Cr(VI) and Cr(III) by hollow fiber liquid phase microextraction combined with flame atomic absorption spectrometry

A new method for the speciation of Cr(VI) and Cr(III) based on enhancement effect of room temperature ionic liquids (RTILs) for hollow fiber liquid phase microextraction (HF-LPME) combined with flame atomic absorption spectrometry (FAAS) was developed. Room temperature ionic liquids (RTILs) and diethyldithiocarbamate (DDTC) were used enhancement reagents and chelating reagent, respectively. The addition of room temperature ionic liquids led to 3.5 times improvement in the determination of Cr(VI). In this method, Cr(VI) reacts with DDTC yielding a hydrophobic complex, which is subsequently extracted into the lumen of hollow fiber, whereas Cr(III) is remained in aqueous solutions. The extraction organic phase was injected into FAAS for the determination of Cr(VI). Total Cr concentration was determined after oxidizing Cr(III) to Cr(VI) in the presence of KMnO4 and using the extraction procedure mentioned above. Cr(III) was calculated by subtracting of Cr(VI) from the total Cr. Under optimized conditions, a detection limit of 0.7ngmL−1 and an enrichment factor of 175 were achieved. The relative standard deviation (RSD) was 4.9% for Cr(VI) (40ngmL−1, n=5). The proposed method was successfully applied to the speciation of chromium in natural water samples with satisfactory results.

Vortex solvent bar microextraction for phthalate esters from aqueous matrices

An improved hollow fiber solvent bar microextraction method termed as vortex solvent bar microextraction (VSBME) was developed. A short hollow fiber immobilized with organic extraction solvent was served as the solvent bar for microextraction of phthalate esters from aqueous matrices. The hydrophobic analytes were pre-focused at the bottom of the vortex under the vigorous magnetic stirring before extraction, which facilitated the mass transfer of analytes from aqueous matrix to organic extraction phase in the subsequent solvent bar microextraction. With the extraction solvent lost gradually from the hollow fiber under the stirring, the efficient extraction was maintained by the absorption of analytes in the porous membrane. After extraction, the analytes were desorbed from the hollow fiber membrane using 50μL organic solvent. The phthalate esters with 1-octanol/water partition coefficients ranging from 1.69 to 8.83 were used as model compounds to investigate the extraction performance. Extraction conditions such as type and volume of extraction solvents, stirring intensity, extraction time, sample concentration and volume were investigated and optimized. Analysis was carried out with gas chromatography–mass spectrometry (GC–MS). Under the optimum conditions, this new method gave super high enrichment factors (over 1500), good reproducibility (<7.1%, n=6) in a rapid extraction within 5min. It allowed the determination of phthalate esters at ngL−1 level. Compared with the other microextraction methods, the proposed VSBME was simpler, more robust and had higher enrichment efficiency. The matrix effects on the extraction performance were also investigated with bottled ice red tea, red wine and human urine.

In-line cold column trapping of organic phase in dispersive liquid–liquid microextraction: Enrichment and determination of curcumin in human serum

A new temperature controlled cold column trapping (CCT) system was developed for in-line sequestration of organic phase in dispersive liquid–liquid microextraction (DLLME) method. In the developed CCT–DLLME method, the dispersed organic extraction phase is solidified and trapped in the CCT, packed with glass particles. Subsequently, the sequestered phase is washed out in an elevated temperature by using an appropriate solvent. The column temperature is controlled by a pair of thermal electric cooler (TEC) plates. The new device is simple and portable and can eliminate the need for centrifugation in the DLLME method for solvents with an appropriate melting point. Some important parameters such as types of extraction and disperser solvents and their volumes, minimum and maximum column temperatures and extraction time were optimized for the extraction of curcumin, as a model compound. Using 1-dodecanol as the organic solvent and acetone as the disperser, recoveries exceeding 90% and a relative standard deviation of 2.87% were obtained for 5 replicated analyses of curcumin by an HPLC method. The detection limit of curcumin (3σ) extracted by the CCT–DLLME system was 28μgL−1. The method was successfully applied to the determination of curcumin in some human serum samples.

Production of 5-Hydroxymethylfurfural from Glucose Using a Combination of Lewis and Brønsted Acid Catalysts in Water in a Biphasic Reactor with an Alkylphenol Solvent

We report the catalytic conversion of glucose in high yields (62%) to 5-hydroxymethylfurfural (HMF), a versatile platform chemical. The reaction system consists of a Lewis acid metal chloride (e.g., AlCl3) and a Brønsted acid (HCl) in a biphasic reactor consisting of water and an alkylphenol compound (2-sec-butylphenol) as the organic phase. The conversion of glucose in the presence of Lewis and Brønsted acidity proceeds through a tandem pathway involving isomerization of glucose to fructose, followed by dehydration of fructose to HMF. The organic phase extracts 97% of the HMF produced, while both acid catalysts remain in the aqueous phase.

An enzyme-based DNA preparation method for application to forensic biological samples and degraded stains

Extraction of DNA from forensic samples typically uses either an organic extraction protocol or solid phase extraction (SPE) and these methods generally involve numerous sample transfer, wash and centrifugation steps. Although SPE has been successfully adapted to the microdevice, it can be problematic because of lengthy load times and uneven packing of the solid phase. A closed-tube enzyme-based DNA preparation method has recently been developed which uses a neutral proteinase to lyse cells and degrade proteins and nucleases [14]. Following a 20min incubation of the buccal or whole blood sample with this proteinase, DNA is polymerase chain reaction (PCR)-ready. This paper describes the optimization and quantitation of DNA yield using this method, and application to forensic biological samples, including UV- and heat-degraded whole blood samples on cotton or blue denim substrates. Results demonstrate that DNA yield can be increased from 1.42 (±0.21)ng/μL to 7.78 (±1.40)ng/μL by increasing the quantity of enzyme per reaction by 3-fold. Additionally, there is a linear relationship between the amount of starting cellular material added and the concentration of DNA in the solution, thereby allowing DNA yield estimations to be made. In addition, short tandem repeat (STR) profile results obtained using DNA prepared with the enzyme method were comparable to those obtained with a conventional SPE method, resulting in full STR profiles (16 of 16 loci) from liquid samples (buccal swab eluate and whole blood), dried buccal swabs and bloodstains and partial profiles from UV or heat-degraded bloodstains on cotton or blue denim substrates. Finally, the DNA preparation method is shown to be adaptable to glass or poly(methyl methacrylate) (PMMA) microdevices with little impact on STR peak height but providing a 20-fold reduction in incubation time (as little as 60s), leading to a ≥1h reduction in DNA preparation time.

Sequential determination of anionic-type detergents by complexation with methylene blue using dual high speed counter-current chromatography

A new dual high-speed counter-current chromatographic system using organic extraction phase and aqueous mobile phase containing methylene blue was applied to the analysis of anionic-type detergents. After selecting appropriate conditions such as flow rate of each mobile phase and sample volume, the new system was successfully applied to the analysis of anionic detergent in river water. As all the analytical procedures can be made in a closed system, the method has no health hazard. The present method is safe, precise, and highly sensitive, and can be applied for sequential determination of multiple samples in a short analysis time.

Primary fatty acid amide metabolism: conversion of fatty acids and an ethanolamine in N18TG2 and SCP cells

Primary fatty acid amides (PFAM) are important signaling molecules in the mammalian nervous system, binding to many drug receptors and demonstrating control over sleep, locomotion, angiogenesis, and many other processes. Oleamide is the best-studied of the primary fatty acid amides, whereas the other known PFAMs are significantly less studied. Herein, quantitative assays were used to examine the endogenous amounts of a panel of PFAMs, as well as the amounts produced after incubation of mouse neuroblastoma N(18)TG(2) and sheep choroid plexus (SCP) cells with the corresponding fatty acids or N-tridecanoylethanolamine. Although five endogenous primary amides were discovered in the N(18)TG(2) and SCP cells, a different pattern of relative amounts were found between the two cell lines. Higher amounts of primary amides were found in SCP cells, and the conversion of N-tridecanoylethanolamine to tridecanamide was observed in the two cell lines. The data reported here show that the N(18)TG(2) and SCP cells are excellent model systems for the study of PFAM metabolism. Furthermore, the data support a role for the N-acylethanolamines as precursors for the PFAMs and provide valuable new kinetic results useful in modeling the metabolic flux through the pathways for PFAM biosynthesis and degradation.

Hollow fiber supported liquid membrane extraction coupled with thermospray flame furnace atomic absorption spectrometry for the speciation of Sb(III) and Sb(V) in environmental and biological samples

A new method of hollow fiber supported liquid membrane extraction (HF-SLME) coupled with thermospray flame furnace atomic absorption spectrometry (TS-FF-AAS) for the speciation of Sb(III) and Sb(V) in environmental and biological samples has been developed. The method is based on the complex of Sb(III) with sodium diethyldithiocarbamate (DDTC). The formed hydrophobic complex is subsequently extracted into the lumen of hollow fiber, whereas Sb(V) is remained in aqueous solutions. The extraction organic phase was injected into TS-FF-AAS for the determination of Sb(III). Total Sb concentration was determined after reduction of Sb(V) to Sb(III) in the presence of l-cysteine and the extraction procedure mentioned above. Sb(V) was calculated by subtracting of Sb(III) from the total Sb. DDTC was used as complexing reagent. 1-Octanol was immobilized in the pores of the polypropylene hollow fiber as liquid membrane and also used as the acceptor solution. Some parameters that influenced extraction and determination were evaluated in detail, such as concentration of sodium diethyldithiocarbamate (DDTC), type of organic solvent, pH of samples, stirring rates, extraction time, as well as interferences. Under optimized conditions, a detection limit of 0.8 ng mL −1 and an enrichment factor of 160 were achieved. The relative standard deviation (RSD) was 6.2% for Sb(III) (50 ng mL −1, n = 5). The proposed method was successfully applied to the speciation of Sb(III) and Sb(V) in environmental and biological samples with satisfactory results.

Enzymatic Resolution of cis-Dimethyl 1-Acetylpiperidine-2,3-Dicarboxylate for Fine Chemicals Preparation

Biocatalysis has become recently a promising tool for chemical synthesis. In particular, enzymes as lipases and esterases are often used to resolve racemicmixtureof esters.Weproposeaenantiospecific enzymatic resolution in order to produce enatiopure synthons precursor of pharmaceutical active substances. The process consists in the enantiospecific hydrolysis of a water-soluble racemic mixture of cis-dimethyl 1-acetylpiperidine2,3-dicarboxylate catalyzed by Candida antarctica lipase B. The separation of product in (2R,3S) configuration from unreacted substrate in (2S,3R) configuration is easily obtained by organic phase extraction. This latter form could be used as enantiomerically pure precursor in the (4aS,7aS)-octahydro-1H-pyrrolo[3,4-b]pyridine synthesis, an expensive building block of the antibiotic Moxifloxacin. By the other hand, the hydrolysed form with (2R,3S) configuration could be used for the preparation of neuromediator analogues. Studies concerning hydrolysis and use of immobilized enzyme has been carried out in order to evaluate its industrial application. The enzyme demonstrate high enantiospecificity, concerning the (2R,3S) enantiomer, and regioselectivity, concerning the ester in position 3. The process has been subject for patent application.

Effect of meconium on surface properties of surfactant monolayers and liposomes

The pathophysiology of meconium aspiration syndrome (MAS) is attributed in part to the development of lung surfactant dysfunction in vivo. Meconium (the first excrement of the newborn) and its components are responsible for development of lung surfactant dysfunction. In this study, the effect of meconium and its components on the surface activity of spread surfactant monolayers was evaluated using Wilhelmy balance at physiological temperature and pH. The effect of meconium on adsorption, airway patency and ultrastructure of liposomes made of various surfactant lipids was also evaluated. Significant inhibition of DPPC monolayer surface activity was observed on addition of meconium, its organic and aqueous phase extracts. All the surfactant lipid mixtures including DPPC attained significantly higher minimum surface tensions (between 12 and 20 mN/m) and lowered monolayer compressibility modulus in presence of meconium suggestive of surfactant monolayer fluidization. Meconium reduced the airway patency and affected the adsorption of DPPC liposomes and was associated with altered ultrastructure of DPPC liposomes. Meconium caused the maximum inhibitory effect on DPPC:PE and DPPC:PG and the least inhibitory effects on DPPC:POPC and DPPC:CHOL in terms of minimum surface tensions. All the surfactants were equally inhibited in terms of airway patency. These findings have implications for the differential inhibition of different surfactants in MAS and for the designing of surfactants that are resistant to meconium inhibition.

Lipase-Catalyzed Polycondensation in Water: A New Approach for Polyester Synthesis

The lipase-catalyzed polycondensation of sebacic aid and 1,4-butanediol can be performed in a biphasic reaction system composed of an aqueous reaction phase and an organic extraction phase. The shift of the equilibrium to higher product yields can be realized by the integrated product removal (IPR). In this biphasic reaction system the product yield, molecular weight and polydispersity is depending on the partitioning of the substrates and the product between the phases. By the biphasic approach substrate inhibition as well as molecular weight and polydispersity can be controlled by medium engineering. The polyester concentration can be increased up to 98% by optimising the reaction conditions. The molecular weight is limited in the biphasic system due to its removal while the polydispersity is independent of the reaction conditions but connected to the biphasic approach. Additional to the conversion the partition coefficients have been investigated either experimentally and via calculation by the quantum...

A comparison between TEHA and Cyanex 923 on the separation and the recovery of sulfuric acid from aqueous solutions

In this study, the separation of sulfuric acid with TEHA and Cyanex 923 from acidic solutions by solvent extraction method was investigated. Extraction of sulfuric acid with TEHA and Cyanex 923 is an exothermic reaction and the enthalpy changes of the reaction were found to be − 6.34 and − 2.24 kJ, respectively. Comprehensive study on determining the stoichiometric coefficients of sulfuric acid in the extraction equation, using slope analysis method, lead to a new approach for this procedure. This study showed that when organic phase extracts more than 100 g/L sulfuric acid, the number of extracted sulfuric acid molecules by TEHA, n, is estimated to be 1. While, each mole of TEHA extracts 2 mol of sulfuric acid when organic phase extracts less than 100 g/L sulfuric acid. In addition, the value of n, using Cyanex 923 as extractant, is estimated to be 1. Using McCabe–Thiele diagram results showed that after 4 stages, sulfuric acid concentration in aqueous phase was reduced from the initial value of 200 to the values of 30 and 5 g/L when octanol concentration in organic phase was 20 and 40%vol, respectively. While, using Cyanex 923 as extractant, 5 stages were needed to reduce the sulfuric acid concentration from 100 to 5 g/L.