Liquid Liquid Extraction

A membrane contactor is a device that achieves gas/liquid or liquid/liquid mass transfer without dispersion of one phase within another. This is accomplished by passing the¯uids on opposite sides of a microporous membrane. By careful control of the pressure difference between the¯uids, one of the¯uids is immobilized in the pores of the membrane so that the¯uid/¯uid interface is located at the mouth of each pore. This approach offers a number of important advantages over conventional dispersed phase contactors, including absence of emulsions, no¯ooding at high¯ow rates, no unloading at low¯ow rates, no density difference between¯uids required, and surprisingly high interfacial area. Indeed, membrane contactors typically offer 30 times more area than what is achievable in gas absorbers and 500 times what is obtainable in liquid/liquid extraction columns, leading to remarkably low HTU values.

Mycotoxins are small (MW ∼700), toxic chemical products formed as secondary metabolites by a few fungal species that readily colonise crops and contaminate them with toxins in the field or after harvest. Ochratoxins and Aflatoxins are mycotoxins of major significance and hence there has been significant research on broad range of analytical and detection techniques that could be useful and practical. Due to the variety of structures of these toxins, it is impossible to use one standard technique for analysis and/or detection. Practical requirements for high-sensitivity analysis and the need for a specialist laboratory setting create challenges for routine analysis. Several existing analytical techniques, which offer flexible and broad-based methods of analysis and in some cases detection, have been discussed in this manuscript. There are a number of methods used, of which many are lab-based, but to our knowledge there seems to be no single technique that stands out above the rest, although analytical liquid chromatography, commonly linked with mass spectroscopy is likely to be popular. This review manuscript discusses (a) sample pretreatment methods such as liquid-liquid extraction (LLE), supercritical fluid extraction (SFE), solid phase extraction (SPE), (b) separation methods such as (TLC), high performance liquid chromatography (HPLC), gas chromatography (GC), and capillary electrophoresis (CE) and (c) others such as ELISA. Further currents trends, advantages and disadvantages and future prospects of these methods have been discussed.

The chemical analysis and quality control of Ginkgo leaves, extracts, phytopharmaceuticals and some herbal supplements is comprehensively reviewed. The review is an update of a similar, earlier review in this journal [T.A. van Beek, J. Chromatogr. A 967 (2002) 21-55]. Since 2001 over 3000 papers on Ginkgo biloba have appeared, and about 400 of them pertain to chemical analysis in a broad sense and are cited herein. The more important ones are discussed and, where relevant, compared with the best methods published prior to 2002. In the same period over 2500 patents were filed on Ginkgo and the very few related to analysis are mentioned as well. Important constituents include terpene trilactones, i.e. ginkgolide A, B, C, J and bilobalide, flavonol glycosides, biflavones, proanthocyanidins, alkylphenols, simple phenolic acids, 6-hydroxykynurenic acid, 4-O-methylpyridoxine and polyprenols. In the most common so-called "standardised" Ginkgo extracts and phytopharmaceuticals several of these classes are no longer present. About 130 new papers deal with the analysis of the terpene trilactones. They are mostly extracted with methanol or water or mixtures thereof. Supercritical fluid extraction and pressurised water extraction are also possible. Sample clean-up is mostly by liquid-liquid extraction with ethyl acetate although no sample clean-up at all in combination with LC/MS/MS is gaining in importance. Separation and detection can be routinely carried out by RP-HPLC with ELSD, RI or MS, or by GC/FID or GC/MS after silylation. Hydrolysis followed by LC/MS allows the simultaneous analysis of terpene trilactones and flavonol aglycones. No quantitative procedure for all major flavonol glycosides has yet been published because they are not commercially available. The quantitation of a few available glycosides has been carried out but does not serve a real purpose. After acidic hydrolysis to the aglycones quercetin, kaempferol and isorhamnetin and separation by HPLC, quantitation is straightforward and yields by recalculation an estimation of the original total flavonol glycoside content. A profile of the genuine flavonol glycosides can detect poor storage or adulteration. Although the toxicity of Ginkgo alkylphenols upon oral administration has never been undoubtedly proven, most suppliers limit their content in extracts to 5 ppm and dozens of papers on their analysis were published. One procedure in which a methanolic extract is directly injected on a C8 HPLC column appears superior in terms of sensitivity (<5 ppm), separation, simplicity and validation and will be incorporated in the European Pharmacopoeia. Alternatively GC/MS and ELISA methods can be used. A sharp contrast to the plethora of papers on terpene trilactones, flavonol glycosides, and ginkgolic acids forms the low number of papers on biflavones, proanthocyanidins, simple phenolics, simple acids, and other constituents that make up the remaining 70% of Ginkgo standardised extracts. More research in this direction is clearly needed. For the analysis of Ginkgo proanthocyanidins (7%) for instance, no reliable assays are yet existing. Finally the growing literature on pharmacokinetic and fingerprinting studies of Ginkgo is briefly summarised.

The development of faster, simpler, inexpensive and more environmentally friendly sample-preparation techniques is an important issue in chemical analysis. Recent research trends involve miniaturisation of the traditional liquid-liquid extraction (LLE) principle by greatly reducing the acceptor-to-donor phase ratio. One of the emerging techniques in this area is liquid-phase microextraction (LPME), where a hollow fibre impregnated with an organic solvent is used to accommodate or protect microvolumes of acceptor solution. This novel methodology proved to be an extremely simple, low-cost and virtually solvent-free sample-preparation technique, which provided a high degree of selectivity and enrichment by additionally eliminating the possibility of carry-over between runs. This article presents the different modes and hollow-fibre configurations of LPME, followed by an up-to-date summary of its applications. The most important parameters and practical considerations for method optimisation are also discussed. The article concludes with a comparison of this novel method with solid-phase microextraction (SPME) and singledrop microextraction (SDME). #

The demand for automation in analytical liquid-liquid extraction (LLE) combined with organic solvent reduction or elimination has led to the recent development of liquid-phase microextraction (LPME) based on disposable hollow fibres. In this concept, analytes of interest are extracted from aqueous samples, through a thin layer of organic solvent immobilized within the pores of a porous hollow fibre, and into an acceptor solution inside the lumen of the hollow fibre. Subsequently, the acceptor solution is directly subjected to a final analysis by capillary gas chromatography (CGC), high-performance liquid chromatography (HPLC), capillary electrophoresis (CE), or mass spectrometry (MS) without any further effort. Hollow fibre-based LPME may provide high analyte pre-concentration and excellent sample clean-up, and it has a broad application potential within areas such as drug analysis and environmental monitoring. This review focuses on basic extraction principles, technical set-up, recovery, enrichment, extraction speed, selectivity, applications, and future trends in hollow fibre-based LPME. #

Ionic liquids (ILs) have been proposed as promising media for the extraction and separation of bioactive compounds from the most diverse origins. This critical review offers a compilation on the main results achieved by the use of ionic-liquid-based processes in the extraction and separation/purification of a large range of bioactive compounds (including small organic extractable compounds from biomass, lipids, and other hydrophobic compounds, proteins, amino acids, nucleic acids, and pharmaceuticals). ILs have been studied as solvents, cosolvents, cosurfactants, electrolytes, and adjuvants, as well as used in the creation of IL-supported materials for separation purposes. The IL-based processes hitherto reported, such as IL-based solid-liquid extractions, IL-based liquid-liquid extractions, IL-modified materials, and IL-based crystallization approaches, are here reviewed and compared in terms of extraction and separation performance. The key accomplishments and future challenges to...

Since 1999, substantial research has been devoted to the development of liquid-phase microextraction (LPME) based on porous hollow fibers. With this technology, target analytes are extracted from aqueous samples, through a thin supported liquid membrane (SLM) sustained in the pores in the wall of a porous hollow fiber, and further into a L volume of acceptor solution placed inside the lumen of the hollow fiber. After extraction, the acceptor solution is directly subjected to a final chemical analysis by liquid chromatography (HPLC), gas chromatography (GC), capillary electrophoresis (CE), or mass spectrometry (MS). In this review, LPME will be discussed with focus on extraction principles, historical development, fundamental theory, and performance. Also, major applications have been compiled, and recent forefront developments will be discussed.

Room temperature ionic liquids (RTILs) have been used as novel solvents to replace traditional volatile organic solvents in organic synthesis, solvent extraction, and electrochemistry. The hydrophobic character and water immiscibility of certain ionic liquids allow their use in solvent extraction of hydrophobic compounds. In this work, a typical room temperature ionic liquid, 1-butyl-3-methylimidazolium hexafluorophosphate [C 4 mim][PF 6 ], was used as an alternative solvent to study liquid/liquid extraction of heavy metal ions. Dithizone was employed as a metal chelator to form neutral metal-dithizone complexes with heavy metal ions to extract metal ions from aqueous solution into [C 4 mim] [PF 6 ]. This extraction is possible due to the high distribution ratios of the metal complexes between [C 4 mim][PF 6 ] and aqueous phase. Since the distribution ratios of metal dithiozonates between [C 4 mim][PF 6 ] and aqueous phase are strongly pH dependent, the extraction efficiencies of metal complexes can be manipulated by tailoring the pH value of the extraction system. Hence, the extraction, separation, and preconcentraction of heavy metal ions with the biphasic system of [C 4 mim][PF 6 ] and aqueous phase can be achieved by controlling the pH value of the extraction system. Preliminary results indicate that the use of [C 4 mim][PF 6 ] as an alternate solvent to replace traditional organic solvents in liquid/liquid extraction of heavy metal ions is very promising.

The continuous quest for novel sample preparation procedures has led to the development of new methods, whose main advantages are their speed and negligible volume of solvents used. The most recent trends include solvent microextraction, a miniaturisation of the traditional liquid^liquid extraction method, where the solvent to aqueous ratio is greatly reduced. Single-drop microextraction is a methodology that evolved from this approach. It is a simple, inexpensive, fast, effective and virtually solvent-free sample pretreatment technique. This article provides a detailed and updated discussion of the developments, modes and applications of single-drop microextraction, followed by a brief description of the theoretical background of the method. Finally, the most important parameters as well as some practical considerations for method optimisation and development are summarised. z2002 Elsevier Science B.V. All rights reserved.

1,3-Propanediol and 2,3-butanediol are two promising chemicals which have a wide range of applications and can be biologically produced. The separation of these diols from fermentation broth makes more than 50% of the total costs in their microbial production. This review summarizes the present state of methods studied for the recovery and purification of biologically produced diols, with particular emphasis on 1,3-propoanediol. Previous studies on the separation of 1,3-propanediol primarily include evaporation, distillation, membrane filtration, pervaporation, ion exchange chromatography, liquid–liquid extraction, and reactive extraction. Main methods for the recovery of 2,3-butanediol include steam stripping, pervaporation, and solvent extraction. No single method has proved to be simple and efficient, and improvements are especially needed with regard to yield, purity, and energy consumption. Perspectives for an improved downstream processing of biologically produced diols, especially 1,3-propanediol are discussed based on our own experience and recent work. It is argued that separation technologies such as aqueous two-phase extraction with short chain alcohols, pervaporation, reverse osmosis, and in situ extractive or pervaporative fermentations deserve more attention in the future.

We describe a sensitive and specific method for measuring cotinine in serum by HPLC coupled to an atmospheric pressure chemical ionization tandem mass spectrometer. This method can analyze 100 samples/day on a routine basis, and its limit of detection of 50 ng/L makes it applicable to the analysis of samples from nonsmokers potentially exposed to environmental tobacco smoke. Analytical accuracy has been demonstrated from the analysis of NIST cotinine standards and from comparative analyses by both the current method and gas chromatography/high-resolution mass spectrometry. Precision has been examined through the repetitive analysis of a series of bench and blind QC materials. This method has been applied to the analysis of cotinine in serum samples collected as part of the Third National Health and Nutrition Examination Survey (NHANES III).

Ionic liquids (ILs) are a novel class of chemical compounds with interesting properties that are driving a lot of research in several fields. For ionic liquids to be effectively used as solvents in liquid-liquid extractions, the knowledge of the mutual solubilities between ILs and the second liquid phase is fundamental. Furthermore, while ILs cannot volatilise and lead to air pollution, even the most hydrophobic ones present some miscibility with water posturing secondary aquatic environmental risks. Despite the importance of the ILs and water systems, there are few extensive reports on their phase equilibria. The aim of this work is to discuss and understand the mutual solubilities of water and imidazolium-based ILs. The results indicate that these mutual solubilities are primarily defined by the anion followed by the cation alkyl side chain length. It was also found that the solubility of the studied ILs in water is more dependent on the ILs structural modifications than the solubility of water in those ILs. The substitution of the most acidic hydrogen in the imidazolium cation by a methyl group leads to different behaviours in both rich-phases, where the solubility of water in ILs showed to be more hydrogen bonding dependent. From the solubility results it can be concluded that the hydrophobicity of the anions increases in the order [BF 4 ] − < [CH 3 (C 2 H 4 O) 2 SO 4 ] − < [C(CN) 3 ] − < [PF 6 ] − < [N(SO 2 CF 3 ) 2 ] − while the hydrophobicity of the cations increases, as expected, with the alkyl chain length increase.

Biodiesel production from abundant bio-sources has drawn the attention of the academic as well as the industrial communities in recent years. However, one of the most serious obstacles for using biodiesel as an alternative fuel is the complicated and costly purification processes involved in its production. The difficulties involved in the separation of glycerine and other un-reacted reactants and by-products necessitate the development of new competent low cost separation processes for this purpose. In this work, a low cost quaternary ammonium salt–glycerine-based ionic liquid is proposed as a solvent for extracting glycerine from the transesterification biodiesel product. The separation technique was tested on palm oil-based produced biodiesel with KOH as a reaction catalyst. The study investigated the effect of DES:biodiesel ratio and the DES composition on the efficiency of the extraction process. The lab scale purification experiments proved the viability of the separation technique with a best DES:biodiesel molar ratio of 1:1 and a DES molar composition of 1:1 (salt:glycerine). The purified biodiesel fulfilled the EN 14214 and ASTM D 6751 standard specifications for biodiesel fuel in terms of glycerine content. A continuous separation process is suggested for industrial scale application.

Modern trends in analytical chemistry are towards the simplification and miniaturization of sample preparation, as well as the minimization of organic solvent used. In view of this aspect, several novel micro-extraction techniques are being developed in order to reduce the analysis step, increase the sample throughput and to improve the quality and the sensitivity of analytical methods. One of the emerging techniques in this area is liquid-phase micro-extraction (LPME). It is a miniaturized implementation of conventional liquid/liquid extraction (LLE) in which only microliters of solvents are used instead of several hundred milliliters in LLE. It is quick, inexpensive and can be automated. In the last few years, LPME has been combined with liquid chromatography (LC) and capillary electrophoresis (CE), besides the generally used coupling to gas chromatography (GC), and has been applied to various matrices, including biological, environmental, and food samples. This work is aimed at providing an overview of the major developments of LPME, coupled with chromatography and CE, as reported in the literature. The paper will focus on the application of the technique to different matrices and the aim is to reveal the panorama of opportunities and to try to indicate the potential of LPME in pesticide analysis. A critical review of the first applications to pesticide analyses is presented in the main part of the manuscript. The optimization of LPME as well as advantages and disadvantages are discussed. It is concluded that, because of its high preconcentration factor, LPME can be introduced with benefit into water analysis for several pesticide groups. In particular, the application of LPME to non-polar pesticides in environmental analysis appears to be promising. However, similar to other micro-extraction techniques, such as solid phase micro-extraction (SPME), serious limitations still remain when analyzing semi-solid and solid environmental, food or biological matrices and/or highly polar compounds. Thus, other pre-concentration techniques may be a good alternative if an analytical problem cannot be sufficiently dealt with LPME.

This research has been focused on a study of sulfolane and four ionic liquids as solvents in liquid-liquid extraction. Liquid-liquid equilibria data were obtained for mixtures of (sulfolane or 4-methyl-N-butylpyridinium tetrafluoroborate ([mebupy]BF 4 ) or 1-ethyl-3-methylimidazolium ethylsulfate ([emim]C 2 H 5 SO 4 ) or 1,3-dimethylimidazolium methylsulfate ([mmim]CH 3 SO 4 ) or 1-butyl-3-methylimidazolium methylsulfate ([bmim]CH 3 SO 4 )) + toluene + n-heptane at T = 313.2 and 348.2 K and p = 0.1 MPa.

Head-column field-amplified sample stacking (head-column FASS) is an efficient, on-line sample concentration technique that can easily provide a sensitivity enhancement of three orders of magnitude. Application of head-column FASS to the capillary electrophoretic analysis of opioid extracts prepared from 20 to 100 ml of human plasma, serum or urine is reported. In the described approach, efficient concentration of cationic opiates from low conductivity extracts of body fluids is effected across a water plug, with separation taking place in a binary buffer comprising 60% (v / v) ethylene glycol, 75 mM Na HPO 2 4

& The determination of trace analytes in complex natural matrices often requires extensive sample extraction and preparation prior to chromatographic analysis. Correct sample preparation can reduce analysis time, sources of error, enhance sensitivity, and enable unequivocal identification, confirmation, and quantification. This overview considers general aspects on sample preparation techniques for trace analysis in various matrices. The discussed extraction=enrichment techniques cover classical methods, such as Soxhlet and liquid-liquid extractions along with more recently developed techniques like pressurized liquid extraction, liquid phase microextraction (LPME), accelerated microwave extraction, and ultrasound-assisted extraction. This overview also deals with more selective methodologies, such as solid phase extraction (SPE), solid phase microextraction (SPME), and stir bar sorptive extraction (SBSE). The adopted approach considers the equilibriums involved in each technique. The applicability of each technique in environmental, food, biological, and pharmaceutical analyses is discussed, particularly for the determination of trace organic compounds by chromatographic methods.

Liquid-liquid extraction of actinides and lanthanides by use of ionic liquids is reviewed, considering, first, phenomenological aspects, then looking more deeply at the various mechanisms. Future trends in this developing field are presented.

A hydrometallurgical route is proposed to recover zinc and manganese from spent alkaline batteries in order to separate base metals such as nickel, copper, aluminium, cadmium, lithium and cobalt which constitute the main metallic species of spent NiCd, NiMH and Li-ion rechargeable batteries. The route comprises the following main steps: (1) sorting batteries by type, (2) battery dismantling to separate the spent battery dust from plastic, iron scrap and paper, (3) leaching of the dust with sulphuric acid and (4) metal separation by a liquid-liquid extraction using Cyanex 272 (bis-2,4,4-trimethylpentyl phosphinic acid) as extractant. The metal content of NiCd, NiMH and Li-ion batteries from three distinct manufacturers has been evaluated. A factorial design of experiments was used to investigate the leaching step using operational variables such as temperature, H 2 SO 4 concentration, S/L ratio and H 2 O 2 concentration. Analysis of metal separation by the liquid-liquid extraction with Cyanex 272 identified a pH 1/2 2.5-3.0 for zinc and aluminium, pH 1/2 4.0-4.5 for manganese, cadmium, copper and cobalt, pH 1/2 6.5 for nickel and pH 1/2 8.0 for lithium. These results indicate that batteries must be previously sorted by type and treated separately. In addition, data fitting to an equilibrium model proposed for the reactive test system by the European Federation of Chemical Engineering (EFChE) have indicated that MR 2 (RH) 2 and MR 2 complexes (where M = Zn, Mn, Co, Cd and Cu) co-exist in the organic phase with Cyanex 272 depending on the loading conditions. The route has been found technically viable to separate the main metallic species of all batteries considered in this study.

A novel analytical approach has been developed and evaluated for the quantitative analysis of a selected group of widely used pesticides (dimethoate, simazine, atrazine, diuron, terbuthylazine, methyl-parathion, methyl-pirimiphos, endosulfan I, endosulfan II, endosulfan sulphate, cypermethrin and deltamethrin), which can be found at trace levels in olive oil and olives. The proposed methodology is based on matrix solid-phase dispersion (MSPD), (with a preliminary liquid-liquid extraction in olive oil samples) using aminopropyl as sorbent material with a clean-up performed in the elution step with Florisil, followed by mass spectrometric identification and quantitation of the selected pesticides using both gas chromatography-mass spectrometry (GC-MS) in selected ion monitoring (SIM) mode and liquid chromatography tandem mass spectrometry (LC-MS-MS) in positive ionization mode. The recoveries obtained (with mean values between 85 and 115% (obtained at different fortification levels) with RSD values below 10% in most cases, confirm the usefulness of the proposed methodology for the analyses of these kind of complex samples with a high fat content. Moreover, the obtained detection limits, which were below 5 g kg −1 by LC-MS analyses and ranged from 10 to 60 g kg −1 by GC-MS meet the requirements established by the olive oil pesticide regulatory programs. The method was satisfactorily applied to different olives and olive oil samples.

A simple reversed phase HPLC method have been successfully developed and validated for the quantitative determination of moxifloxacin (MOX) in bulk material, pharmaceutical formulation and serum. Purospher STAR C 18 (25 cm´4.6 mm, 5 mm) and Discovery C 18 (25 cm´4.6 mm, 5 mm) columns were used. The mobile phase, methanol: acetonitrile: water (85:5:10, v/v/v), pH 2.75 adjusted by phosphoric acid was delivered at a flow rate of 1 mL min -1 . The eluents was monitored using UV detector at 290 nm. The proposed method is specific, accurate (99.39-102.67%), precise (intra-day variation 0.04-0.86% and inter-day variation 0.12-0.94%) and linearity (R 2 > 0.999) within the desired range 0.39-25 mg mL -1 concentration. The detection and quantification limit was 0.002-0.51 mg mL -1 and 0.01-0.555 mg mL -1 , respectively. The analysis of variance (ANOVA) and student's t-test were applied to verify the results. The anticipated method is applicable to routine analysis of MOX in pharmaceutical formulations and human serum samples. It is also applied on interaction of MOX with several essential and trace metals as well as interaction with antacids.

Lead is recognized worldwide as a poisonous metal. Thus, the determination of this element is often required in environmental, biological, food and geological samples. However, these analyses are difficult because such samples contain relatively low concentrations of lead, which fall below the detection limit of conventional analytical techniques such as flame atomic absorption spectrometry and inductively coupled plasma optical emission spectrometry. Several preconcentration procedures to determine lead have therefore been devised, involving separation techniques such as liquid–liquid extraction, solid phase extraction, coprecipitation and cloud point extraction. Citing 160 references, this paper offers a critical review of preconcentration procedures for determining lead using spectroanalytical techniques.

One of the factors that may explain nowadays honeybees’ colonies losses is the increasing presence of chemicals in the environment. The aim of this study is to obtain a global view of the presence of environmental contaminants in beehives and, develop a fast, cheap and sensitive tool to analyze environmental contaminants in apiarian matrices. A multi residue analysis was developed

Two-phase systems can be exploited in separation science for the extraction/purification of desired biomolecules. This article reviews recent experimental work on the use of aqueous two-phase polymer systems, two-phase aqueous micellar systems and reversed micellar systems for the extraction/purification of biomolecules. The experimental partitioning behavior of different biomolecules is reviewed and new results with nisin and lipopolysaccharides are presented. An extensive description of each system is presented, based on the biomolecules behavior and the tools employed to improve their extraction and purification. Copyright © 2007 Society of Chemical Industry

English Publication Type: Journal Analyte: proteins -identn. of, involved in apoptosis regulation, by bioassay, digestion, gel electrophoresis, MALDI MS, PCR and Western blotting Technique: bioassay digestion electrophoresis, gel mass spectrometry, matrix-assisted laser desorption-ionization (MALDI MS) polymerase chain reaction (PCR) Western blotting Abstract: Global approaches like proteome or transcriptome analyses have been performed extensively to identify candidate genes or proteins involved in biological and pathological processes. Here we describe the identification of proteins implicated in the regulation of apoptosis using proteome analysis and the functional validation of targets by RNA interference. A high-throughput platform for the validation of synthetic small interfering RNAs (siRNAs) by quantitative real-time PCR was established. Genes of the identified factors were silenced by automated siRNA transfection, and their role in apoptotic signaling was investigated. Using this strategy, nine new modulators of apoptosis were identified. A subsequent detailed study demonstrated that hepatoma-derived growth factor (HDGF) is required for TNF -induced release of pro-apoptotic factors from mitochondria. The strategy described here may be used for hypothesis-free, global gene function analysis.

The ideal method to produce a terminal metabolite inhibitor of cell growth and production is to remove and recover it from the fermenting broth as it is formed. Extractive fermentation is achieved in the case of ethanol production by coupling both fermentation and liquid-liquid extraction. The solvent of extraction is 1-dodecanol (or a mixture 1-dodecanol, 1-tetradecanol); study of the inhibitory effect of primary aliphatic alcohols of different chain lengths shows that no p w t h is observed in the presence of alcohols which have between 2 and 12 carbons. This effect is suppressed when the carbon number is 12 or higher. A new reactor has been used-a pulsed packed column. Pulsation is performed pneumatically. Porous material used as a package adsorbs the cells. The fermentation broth is pulsed in order to 1) increase the interfacial area between the aqueous phase and the dodecanol, 2) decrease gas holdup. Alcoholic fermentation, performed at 35°C on glucose syrup, permits the total utilization of glucose solution of 409 g/L with a yeast which cannot-in classical pnxesses-completely use solutions with 200 g/L of glucose. The feasibility of a new method of fermentation coupling both liquid-liquid extraction and fermentation is demonstrated. Extension of this method is possible to any microbial production inhibited by its metabolite excretion.

Different inner-sphere coordination environments are observed for the uranyl nitrate complexes formed with octyl-phenyl-N,Ndiisobutylcarbamoylmethylphosphine oxide and tributyl phosphate in dodecane and in the hydrophobic ionic liquids (ILs) [C 4 mim]- [PF 6 ] and [C 8 mim][N(SO 2 CF 3 ) 2 ]. Qualitative differences in the coordination environment of the extracted uranyl species are implied by changes in peak intensity patterns and locations for uranyl UV− visible spectral bands when the solvent is changed. EXAFS data for uranyl complexes in dodecane solutions is consistent with hexagonal bipyramidal coordination and the existence of UO 2 (NO 3 ) 2 -(CMPO) 2 . In contrast, the complexes formed when uranyl is transferred from aqueous nitric acid solutions into the ILs exhibit an average equatorial coordination number of approximately 4.5. Liquid/liquid extraction results for uranyl in both ILs indicate a net stoichiometry of UO 2 (NO 3 )(CMPO) + . The concentration of the IL cation in the aqueous phase increases in proportion to the amount of UO 2 (NO 3 )(CMPO) + in the IL phase, supporting a predominantly cation exchange mechanism for partitioning in the IL systems.

Aqueous two-phase extraction is employed for the first time for separation and purification of mixture of enzymes (bromelain and polyphenol oxidase) from the pineapple (Ananas comosus L. Merr.). Influence of several parameters such as phase forming polymer molecular weight (polyethylene glycol 1500-20,000), concentration of phase forming components (polyethylene glycol, 12-18%, w/w, and potassium phosphate, 14-20%, w/w) and system pH (6.0-9.0) on differential partitioning of bromelain and polyphenol oxidase required for the purification is studied. Bromelain preferentially partitioned to the top (polyethylene glycol) phase, while polyphenol oxidase to the bottom (potassium phosphate) phase. Partition coefficient of both the enzymes decreased with an increase in molecular weight of polyethylene glycol. Phase composition of the system was found to have significant effect on enzyme partitioning and degree of purification. The polyethylene glycol/potassium phosphate system (comprising of 18% PEG 1500 and 14% phosphate) resulted in about 228% activity recovery and 4.0-fold increase in purity in case of bromelain and about 90% activity recovery and 2.7-fold increase in purity of polyphenol oxidase.

In this paper, investigations have been carried out to determine the suitability of imidazolium-based ionic liquids (ILs), 1-methyl-3alkylimidazolium hexafluorophosphate [C n mim][PF 6 ] (n = 4, 6, 8) and 1-methy-3-alkylimidazolium tetrafluoroborate [C n mim][BF 4 ] (n = 6, 8), in replacing volatile organic solvents for liquid-liquid extraction of selected endocrine-disrupting phenols from aqueous solutions. New experimental data have been reported for the extraction of phenol, bisphenol A, pentachlorophenol, 4-octylphenol and 4-nonylphenol by the ILs. The results showed that distribution ratios of the endocrine-disrupting phenols were influenced significantly by pH of the aqueous phase, nature of the ILs, chemical structure of the phenols, and the presence of some salts in aqueous solutions. It was found that in the range of pH <7, most of the phenols were extracted quantitatively from aqueous solution into the ILs. The selective separation of some of the phenols from their binary mixtures was also investigated, and the possible driven forces for the extraction were discussed based on the hydrogen-bonding and hydrophobic interactions between the ILs and the phenols. It is expected that these results are promising for the liquid-liquid extraction, separation and preconcentration of endocrine-disrupting phenols in analytical science and related industrial process.

Aqueous biphasic systems (ABS) provide an alternative and efficient approach for the extraction, recovery and purification of biomolecules through their partitioning between two liquid aqueous phases. In this work, the ability of hydrophilic phosphoniumbased ionic liquids (ILs) to form ABS with aqueous K 3 PO 4 solutions was evaluated for the first time. Ternary phase diagrams, and respective tie-lines and tie-lines length, formed by distinct phosphonium-based ILs, water, and K 3 PO 4 at 298 K, were measured and are reported. The studied phosphonium-based ILs have shown to be more effective in promoting ABS compared to the imidazolium-based counterparts with similar anions. Moreover, the extractive capability of such systems was assessed for distinct biomolecules (including amino acids, food colourants and alkaloids). Densities and viscosities of both aqueous phases, at the mass fraction compositions used for the biomolecules extraction, were also determined. The evaluated IL-based ABS have been shown to be prospective extraction media, particularly for hydrophobic biomolecules, with several advantages over conventional polymer-inorganic salt ABS.

Two approaches based on sorptive extraction, solid-phase microextraction (SPME) and stir bar sorptive extraction (SBSE), in combination with liquid chromatography (LC)-atmospheric pressure chemical ionization mass spectrometry (MS) have been assayed for analyzing chlorpyriphos methyl, diazinon, fonofos, phenthoate, phosalone, and pirimiphos ethyl in honey. In both, SPME and SBSE, enrichment was performed using a poly(dimethylsiloxane) coating. Significant parameters affecting sorption process such as sample volume, sorption and desorption times, ionic strength, elution solvent, and dilution (water/honey) proportion were optimized and discussed. Performance of both methods has been compared through the determination of linearity, extraction efficiencies, and limits of quantification. Relative standard deviations for the studied compounds were from 3 to 10% by SPME and from 5 to 9% by SBSE. Both methods were linear in a range of at least two orders of magnitude, and the limits of quantification reached ranging from 0.04 to 0.4 mg kg −1 by SBSE, and from 0.8 to 2 mg kg −1 by SPME. The two procedures were applied for analyzing 15 commercial honeys of different botanical origin. SPME and SBSE in combination with LC-MS enabled a rapid and simple determination of organophosphorus pesticides in honey. SBSE showed higher concentration capability (large quantities of sample can be handled) and greater accuracy (between 5 and 20 times) and sensitivity (between 10 and 50 times) than SPME; thus, under equal conditions, SBSE is the recommended technique for pesticide analysis in honey.

A hydrometallurgical route based on the liquid-liquid extraction technique using Cyanex 272 as extractant is investigated for the selective separation of metal values, in particular, zinc and manganese from spent alkaline batteries. The recycling route consists of following steps: (1) cryogenic dismantling of the spent batteries, (2) pre-treatment of the internal material consisting of drying, grinding and screening steps in order to produce a dry homogeneous powder, (3) leaching of the powder with sulphuric acid and (4) metal separation by liquid-liquid extraction. Bench scale experiments have shown that zinc and manganese are easily separated (DpH 1=2 % 2:0) using 20% (v/v) Cyanex 272 dissolved in Escaid 110 at 50 8C. Therefore, the proposed route can treat residues from both zinc-carbon and alkaline batteries because metal composition of these batteries is quite similar. The metal content of other batteries such as Ni-Cd and nickel-metal hydride (NiMH) has been also determined in order to include them in future investigations. #

Oral fluid is an alternative matrix with potential applications in road-side drug screening, work-place testing, drug treatment programs, and epidemiological surveys. Development of methods for extensive drug screening in oral fluid is warranted. We developed a liquid chromatography- tandem mass spectrometry (LC-MS/MS) method for drug screening of preserved oral fluid collected with the Intercept collection device. Samples were prepared by liquid-liquid extraction with ethylacetate/heptane (4:1). LC-separation was achieved with an Atlantis dC18-column (2.1 x 50 mm, 3 microm particle). Mass detection was performed by positive ion mode electrospray LC-MS/MS and included the following drugs/metabolites: morphine, 6-monoacetylmorphine, codeine, buprenorphine, methadone, amphetamine, methamphetamine, 3,4-methylenedioxymethamphetamine, 3,4-methylenedioxyamphetamine, 3,4-methylenedioxyethylamphetamine, cocaine, benzoylecgonine, Delta-9-tetrahydrocannabinol, lysergic acid diethylamide, alprazolam, bromazepam, clonazepam, 7-aminoclonazepam, diazepam, N-desmethyldiazepam, 3-OH-diazepam, fenazepam, flunitrazepam, 7-aminoflunitrazepam, lorazepam, nitrazepam, 7-aminonitrazepam, oxazepam, zopiclone, zolpidem, carisoprodol, and meprobamat. Screening of 32 drugs was performed with a run time of 14 min. Within- and between-day relative CVs varied from 2.0% to 31.8% and from 3.6% to 39.1%, respectively. Extraction recoveries were &amp;amp;amp;amp;amp;gt;50% except for morphine (30%) and benzoylecgonine (0.2%). The concentrations of the lowest calibrator were 1 nmol/L (0.28 microg/L) to 500 nmol/L (68 microg/L), depending on the drug. The method allowed rapid and sensitive oral fluid screening for the most commonly abused drugs in Norway and will be used for a road-side survey of drug use in normal traffic.

Sample preparation is an important step in the development of an analytical method but is often regarded as time-consuming, laborious work. Optimum sample preparation leads to enhanced selectivity and sensitivity, however, and reduces amounts of interfering matrix compounds, resulting in less signal suppression or enhancement. Recent developments in extraction techniques that could be of interest in clinical and forensic toxicology, for example liquid-liquid, solid-phase, and headspace extraction, are summarized in this review. The advantages and disadvantages of several extraction techniques are discussed, to enable the reader to choose an appropriate method of extraction for his or her application. Attention is paid to current trends in analytical toxicology, for example miniaturization, high throughput, and automation.

Public health agencies in many countries rely on detection by mass spectrometry for unambiguous identification of residues of antibiotic and antibacterial agents in animal food products for human consumption. The introduction of relatively inexpensive and robust LC-MS systems has given a strong impulse to develop determinative and confirmatory methods for the above medicines in foodstuffs. This impulse has been also dictated by thermal instability and lack of volatility of many antibiotics and antibacterials that makes the GC-MS technique of difficult application. Analytical methods developed for analyzing components of the major classes of the medicines mentioned above are here reviewed. The discussion is focused on both sample treatment and final LC-MS analysis. 

Islets of Langerhans are responsible for maintaining glucose homeostasis through regulated secretion of hormones and other factors. It is hypothesized that amino acids secreted from islets play a critical role in cell functionality and viability. For example, glutamate and gamma-aminobutyric acid (GABA) have been proposed to work as paracrine signaling molecules within islets to coordinate the release of hormone secretion; other amino acids, such as glutamine, leucine, alanine, and arginine have been shown to stimulate or potentiate glucose-stimulated insulin secretion. To characterize the potential roles that these small molecules may play in islet physiology, derivatization of amino acids in high salt buffers commonly used in islet experiments with naphthalene-2,3-dicarboxaldehyde and MEKC separation conditions were optimized. The optimized conditions used D-Norvaline as the internal standard and allowed quantification of 14 amino acids with LODs ranging from 0.2 -7 nM. The RSD of the migration times were 0.04 -0.54% and the RSD of the peak areas were 0.2 -5.8% for the various amino acids. The effects of glucose and 2,4-dinitrophenol on amino acid secretions from islets were tested and a suppressive effect of glucose on GABA release was observed, likely acting through ATP inactivation of glutamate decarboxylase.

Legumes form a symbiosis with rhizobia in which the plant provides an energy source to the rhizobia bacteria that it uses to fix atmospheric nitrogen. This nitrogen is provided to the legume plant, allowing it to grow without the addition of nitrogen fertilizer. As part of the symbiosis, the bacteria in the infected cells of a new root organ, the nodule, are surrounded by a plant-derived membrane, the symbiosome membrane, which becomes the interface between the symbionts. Fractions containing the symbiosome membrane (SM) and material from the lumen of the symbiosome (peribacteroid space or PBS) were isolated from soybean root nodules and analyzed using non-gel proteomic techniques. Bicarbonate stripping and chloroform-methanol extraction of isolated SM were used to reduce complexity of the samples and enrich for hydrophobic integral membrane proteins. One hundred and ninety-seven proteins were identified as components of the SM, with an additional fifteen proteins identified from pe...

In this study we present a report of investigation from the screening of perfluorooctanoic acid and perfluorooctane sulfonate in Lake Victoria Gulf and in its source rivers. The first determined levels of perfluorinated alkylated substances in Lake Victoria ecosystem are presented. Variability in the concentrations of perfluorooctanoic acid or perfluorooctane sulfonate in river waters (range perfluorooctanoic acid 400-96,400 and perfluorooctane sulfonate \400-13,230 pg/L) was higher than for Lake waters (range perfluorooctanoic acid 400-11,650 and perfluorooctane sulfonate \400-2,530 pg/L respectively) suggesting generalized point sources such as domestic and industrial waste. The lowest limit of quantification was 400 pg/L for both analytes and limit of detection were 75 and 40 pg/L for perfluorooctanoic acid and perfluorooctane sulfonate respectively. Typical values for precision obtained were 0.14-3.7%, with concentrations range from 400 pg/mL to 1 lg/mL).

Plants are the main source of molecules with antioxidant and radical scavenging properties that aid the natural defence systems of cells and may be involved in the preservation of human health, particularly preventing all the physiopathological conditions where oxidative damage is a hallmark. Achillea collina Becker ex Rchb. is a medicinal plant of the Achillea millefolium aggregate (yarrow) traditionally used, particularly in mountain areas, as an infusion or alcohol extract for its digestive, antiinflammatory, analgesic, antipyretic and wound healing properties. The aim of this study was to investigate the antioxidant capacity and cytoprotective activity against oxidative stress of infusions obtained from the leaves and inflorescences of Achillea collina Becker ex Rchb., assessed by chemical (free radical scavenging activity by DPPH and Folin Ciocalteu assay) and biological assays (in vitro model of cytotoxicity and lipid peroxidation in PC12 cells line). Infusions of leaves had the highest antioxidant properties and cytoprotective activity. The antioxidant capacity was significantly correlated with the total phenolic content but not with the cytoprotective profile. Achillea collina Becker ex Rchb. has good antioxidant and cytoprotective properties, suggesting further investigations on its chemical composition and potential health value, particularly for traditionally prepared infusions of leaves. Copyright © 2008 John Wiley & Sons, Ltd.

The recovery of proteins using reversed micelles is a liquid-liquid extraction process that has received increasing attention since proteins were shown to be solubilized in organic solvents with surfactants, maintaining their functional properties, and to be transferred between an aqueous solution and a reversed micellar organic phase. This article reviews the application of reversed micellar systems as a bioseparation technique for isolation and purification of proteins. The parameters that affect protein solubilization into the reversed micelles and the equilibrium and kinetics aspects that are involved in the extraction and back-extraction of proteins are discussed. Several examples are also described including the application of this technique for purification of recombinant proteins: cytochrome b 5 and a cutinase from Fusarium solani pisi.

A simple procedure based on stir bar sorptive extraction (SBSE) and high-performance liquid chromatography-fluorescence detection (HPLC-FLD) is presented for the determination of 15 polycyclic aromatic hydrocarbons (PAHs) in herbal tea prepared with Mate leaves (Ilex paraguariensis St. Hil.). The influence of methanol and salt addition to the samples, the extraction time, the desorption time and the number of desorption steps, as well as the matrix effect, were investigated. Once the SBSE method was optimised (10 mL of Mate tea, 2 h extraction at room temperature followed by 15 min desorption in 160 L of an acetonitrile (ACN)-water mixture), analytical parameters such as repeatability (≤10.1%), linearity (r 2 ≥ 0.996), limit of detection (LOD, 0.1-8.9 ng L −1 ), limit of quantitation (LOQ, 0.3-29.7 ng L −1 ) and absolute recovery (24.2-87.0%) were determined. For calibration purposes, a reference sample was firstly obtained by removing the analytes originally present in the lowest contaminated Mate tea studied (via SBSE procedure) and then spiked at 1-1200 ng L −1 range. The proposed methodology proved to be very convenient and effective, and was successfully applied to the analysis of 11 Mate tea samples commercialised in Brazil. The results of the commercial Mate tea samples found by the SBSE approach were compared with those obtained by liquid-liquid extraction (LLE), showing good agreement.

The selection of separation process of organic compounds is a critical issue in the chemical industry. Different conventional methods, such as coagulation, precipitation, ion exchange, electrodialysis, adsorption, ultrafiltration and liquid-liquid extraction have been used for the separation processes since last so many years, but supported liquid membrane (SLM)-based separation processes have been predicted as a promising option. Ionic liquids (ILs) are considered a new miraculous chemical due their unique properties and large variety of applications in all areas of the chemical sciences. The use of ionic liquids as a liquid membrane phase results in the stabilization of the SLMs due to their negligible vapor pressure, possibility of minimizing their solubility in the surrounding phases and greater capillary force associated with their high viscosity, which can reduce the displacement of liquids from micron pores under pressure. This review article summarizes the role of ionic liquids in supported liquid membrane technology for extraction processes, stability of the membranes and show promise in the liquid/liquid extraction of organics from water, gases, amino acids, toxic metal ions from their aqueous solution and separating isomeric organic compounds. © 2011 Elsevier B.V.

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