Miniaturized dynamic liquid-liquid extraction of organophosphate triesters from blood plasma using the hollow fibre-based XT-tube extractor

A miniaturized liquid–liquid extractor for bioanalytical sample preparation is described. The extractor consists of a polypropylene hollow fibre mounted inside polytetrafluoroethylene (PTFE) tubing by means of a cross (X) connector and a tee (T) connector. All parts are commercially available, inexpensive, and easily assembled. The aqueous sample, injected into a carrier flow, is pumped along the outside of the fibre and the organic phase, which also wets the pores of the hollow fibre wall, is pumped inside. Eight organophosphate triester (OPE) plasticisers/flame retardants were extracted from 50 µL spiked blood plasma that had been mixed with 50 µL formic acid to denature plasma proteins. The organic phase was a mixture of hexane and methyl tert-butyl ether (MTBE). A high concentration of formic acid in the sample and of MTBE in the organic phase had positive effects on the recovery of some OPE. When investigating the recovery as a function of extraction time it was found that the extraction reached a maximum after 10 min, at a flow-rate of 15 µL min^–1. Recoveries varied between 40 and 80% with RSD around 4% for most compounds. The whole 150-µL extract was injected into a GC–MS system equipped with a programmed-temperature vaporization (PTV) injector. With the MS in selected-ion monitoring (SIM) mode, the LOD for triphenyl phosphate and 2-ethylhexyl diphenyl phosphate were 0.3 and 0.2 ng mL^–1, respectively. More than 40 plasma extractions were performed with the same fibre without any detectable change in extraction efficiency.     

Matrix solid-phase dispersion extraction of sulfonamides from blood

Matrix solid-phase dispersion extraction was applied to the extraction of sulfadiazine, sulfamerazine, and sulfamethazine from human and animal bloods. The separation and determination of the analytes were carried out by high-performance liquid chromatography. The effects of the types of the dispersion adsorbents and elution solvents were investigated, and the highest recovery was obtained when diatomaceous earth was used as the dispersion adsorbent, while acetone was used as the elution solvent. Under the optimal conditions, the linear range for determining the sulfonamides in blood samples was 0.020-10.0 μg/mL, and the average recoveries of the three sulfonamides were higher than 87.5%.     

Study of liquid-liquid extraction of perrhenate with cyclohexanone in different media

A study has been made of the extraction of ReO(4)(-) from the following media: nitric, hydrochloric, sulphuric and phosphoric acids, and sodium nitrate, chloride, sulphate, carbonate and hydroxide solutions. The extraction curves were obtained and hydration and solvation numbers determined. It is concluded that in acidic medium the extraction follows a hydratosolvate mechanism; in neutral and alkaline medium only a solvate mechanism is observed. Similar investigations were carried out with molybdenum(VI). The separation of rhenium and molybdenum is discussed.     

Separation of uranium from different uranium oxide matrices employing supercritical carbon dioxide extraction

Uranium from different uranium oxide matrices was extracted with tri-n-butyl phosphate–nitric acid (TBP–HNO₃) adduct using supercritical carbon dioxide (SC CO₂). While 30 min dissolution time at 323 K was sufficient for U₃O₈ and UO₂ powder, UO₂ granule (at 333 K) and crushed green pellet (at 353 K) required 40 min. Crushed sintered pellet required 60 min at 353 K for complete dissolution. Influence of various experimental parameters such as temperature, pressure, volume of TBP–HNO₃ adduct, acidity of nitric acid used for preparing TBP–HNO₃ adduct and extraction time on uranium extraction efficiency was also investigated. For UO₂ powder, temperature of 323 K, pressure of 15.2 MPa, 1 mL TBP–HNO₃ adduct, 10 M nitric acid and 30 min extraction time was found to be optimum. ~70% uranium extraction efficiency was obtained on extraction with SC CO₂ alone which increased to 90% with the addition of 2.5% TBP in SC CO₂ stream. Extraction efficiency was found to vary linearly with TBP percentage and nearly complete uranium extraction (~99%) was observed with 20% TBP. Nearly complete extraction was also achieved with addition of 2.5% thenoyltrifluoroacetylacetone (TTA) in methanol. The optimized procedure was extended to remove uranium from simulated tissue paper waste matrix smeared with uranium oxide solids.     

Studies on the extraction of sulfonamides from agricultural soils

The extraction of six sulfonamides (sulfadiazine, sulfadimidine, sulfathiazole, sulfachloropiridazine, sulfadimethoxine, and sulfaquinoxaline) from soils with different physicochemical characteristics and at several aging times was investigated. Conventional mechanical shaking, microwave-assisted extraction, ultrasound probe-assisted extraction and pressurized liquid extraction techniques were evaluated. The four techniques provided similar results when applied to freshly contaminated soils. However, microwave-assisted extraction was the most suitable to extract sulfonamide aged residues from soils. Microwave-assisted extraction was applied to eight soils aged for 3 months, using acetonitrile:buffer pH 9 (20:80) as the extraction solvent, and recoveries ranged from 15–25% for STZ to 42–64% for SDM.     

Ionic liquid-salt aqueous two-phase extraction based on salting-out coupled with high-performance liquid chromatography for the determination of sulfonamides in water and food

Ionic liquid-salt aqueous two-phase extraction coupled with high-performance liquid chromatography with ultraviolet detection was developed for the determination of sulfonamides in water and food samples. In the procedure, the analytes were extracted from the aqueous samples into the ionic liquid top phase in one step. Three sulfonamides, sulfamerazine, sulfamethoxazole, and sulfamethizole were selected here as model compounds for developing and evaluating the method. The effects of various experimental parameters in extraction step were studied using two optimization methods, one variable at a time and Box–Behnken design. The results showed that the amount of sulfonamides did not have effect on the extraction efficiency. Therefore, a three-level Box–Behnken experimental design with three factors, which combined the response surface modeling, was used to optimize sulfonamides extraction. Under the most favorable extraction parameters, the detection limits (S/N?=?3) and quantification limits (S/N?=?10) of the proposed method for the target compounds were achieved within the range of 0.15–0.3 ng/mL and 0.5–1.0 ng/mL from spiked samples, respectively, which are lower than or comparable with other reported approaches applied to the determination of the same compounds. Finally, the proposed method was successfully applied to the determination of sulfonamide compounds in different water and food samples and satisfactory recoveries of spiked target compounds in real samples were obtained.     

Separation of boric acid from radioactive wastes by liquid-liquid extraction

The extraction of boric acid from a solution modeling radioactive waste has been studied. Different aliphatic alcohols were used as extractants. Factors affecting the distribution ratio of boric acid and the behaviour of some other components of the solution under conditions of boric acid extraction were investigated. The composition of species extracted was determined from distribution data of n-hexanol and H₃BO₃.     

Solid-liquid separation after liquid-liquid extraction

A low-melting solid is used as organic solvent for liquid-liquid extraction at elevated temperatures followed by solidification and decantation of the aqueous phase.     

Preconcentration in multistage liquid-liquid extraction

Theoretical possibilities of the preconcentration of solutes in multistage static liquid-liquid extraction have been investigated. It was found that the preconcentration increases with increasing distribution ratio of the solutes between two phases as well as with the number of stages (n) and reaches its maximum value for n approaching infinity, i.e., in dynamic extraction. Comparison of the preconcentration in multistage (P_ns) and one-stage (p_1s) static operations shows that the relative preconcentration (q_ns=p_ns/p_1s) increases to infinity as the separation efficiency approaches 100%. Some of these theoretical considerations have been confirmed in extraction of radioiodine from aqueous solutions.Presented at the 2nd International Conference on the Separation of Ionic Solutes, SIS'87, Smolenice, Czechoslovakia, October 12–15, 1987.     

Integrated continuous microfluidic liquid-liquid extraction

We describe continuous flow liquid-liquid phase separation in microfluidic devices based on capillary forces and selective wetting surfaces. Effective liquid-liquid phase separation is achieved by using a thin porous fluoropolymer membrane that selectively wets non-aqueous solvents, has average pore sizes in the 0.1-1 microm range, and has a high pore density for high separation throughput. Pressure drops throughout the microfluidic network are modelled and operating regimes for the membrane phase separator are determined based on hydrodynamic pressure drops and capillary forces. A microfluidic extraction device integrating mixing and phase separation is realized by using silicon micromachining. Modeling of the phase separator establishes the operating limits. The device is capable of completely separating several organic-aqueous and fluorous-aqueous liquid-liquid systems, even with high fractions of partially miscible compounds. In each case, extraction is equivalent to one equilibrium extraction stage.     

Miniaturized solid-phase extraction with resin disks

The properties and advantages of membrane disks for solid-phase extraction (SPE) are described. Miniaturization is a trend in SPE, as well as chemical analysis in general. A semimicro method is reviewed in which an extraction disk 4 mm in diameter is used for SPE. Even smaller scale separations are possible with a device in which a membrane 0.7 mm in diameter was incorporated into the needle of a 50-micro syringe. Aqueous samples containing 10 ppb of eight substituted benzenes were passed through the miniaturized-SPE syringe automatically using a single-syringe infusion pump. Elution volumes of 5 microl provided 500-fold concentrations and delivered average recoveries greater than 90% and an average relative standard deviation (RSD) of 4.6% for the analytes. Direct injection of the 5 microl eluate from the miniaturized-SPE syringe into a gas chromatograph also produced average recoveries greater than 90% and an average RSD of 6.2%.     

Supercritical fluid extraction and gas chromatography or electroanalysis of metal chelates from different sample matrices

The supercritical fluid extraction of Pb(DDC)2 and MoO2(acac)2 complexes is performed. The previously formed complexes are used in order to simplify the extraction process. In the extraction cell, 9.0 mg of Pb(DDC)2 or 30.0 mg of MoO2(acac)2 is added. With these two complexes, a study of static and dynamic extraction as a function of pressure (1000-2500 psi), temperature (40-160 degrees C), and presence of modifier (methanol) is performed. Under the best conditions, 5.6 mg of Pb(DDC)2 (2.3 mg of Pb2+) is recovered. The parameters are 2500 psi of pressure, 160 degrees C of temperature, 0.5 mL methanol (placed in a 10-mL extraction cell), 60.0 min of static extraction, and 2.0 min of dynamic extraction. It is necessary to add 3.0 mL of methanol to enhance efficiency on the MoO2(acac)2 complex recovery. Quantitative extractions of MoO2(acac)2 (9.0 mg of MoVI) are obtained when the experiments are carried out under 1000-2500 psi of pressure, 140 degrees C, and times no longer than 10.0 min. Then, the study is carried out forming the in situ complexes. For this purpose, metallic ion and ligand are added. Under these conditions, the Pb2+ recovery decreases from 2.3 to 1.9 mg, and the MoVI recovery decreases from 9.0 to 1.0 mg. When 1.9 mg of Pb2+ and 1.0 mg of MoVI or less is placed in the extraction cell, the recoveries are always 100%. The Pb2+ extracts are directly accomplished using gas chromatography-flame ionization detection (GC-FID), and the MoVI extracts are analyzed using GC-FID and catalytic adsorption voltammetry. The quantitation of pure extracts is carried out by constructing calibration curves with complex solutions and sample solutions using the standard addition method. This method is applied by determination of Pb2+ in sodium alginate extracted from algae and blood, urine, and human milk from patients with diagnosed plumbunemy. MoVI is determined in irrigation water and pasture of animal intake.     

The separation of micro-amounts of indium from zinc by liquid-liquid extraction

Summary The study of a method for the determination of indium in zinc by radioactivation created the necessity for the isolation of indium after irradiation. The separation procedure based on the extractability of InBr3 into diethylether is not achievable in the presence of zinc. The distribution coefficients as determined by the use of radioactive⁶⁵Zn for awide range of hydrobromic acid concentrations and metal ion concentrations are relatively high, corresponding to a 9% extraction.Further experiments showed the possibility of such a separation when ethylether was replaced by isopropylether. The extractability of ZnBr₂ in this solvent is negligible in the acidity range 0.5 to 6 M HBr.The results of the distribution of indium tribromide obtained from the activity measurements when radioactive¹¹⁴In has been used as tracer, have demonstrated quantitative recovery of indium in a single extraction from 6 M HBr.The volume changes of the two phases are very small in comparison to those arising when diethylether is used as solvent.Because of its simplicity and efficiency, this separation method could prove very convenient in the analysis of metallic zinc and zinc concentrates in which indium is to be determined.

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Zusammenfassung Die Ausarbeitung einer Methode zur Bestimmung von Indium in Zink auf radioaktivem Wege ergab die Notwendigkeit, das Indium nach der Bestrahlung zu isolieren. Die Trennung durch Extraktion des InBr₃ mit Diäthyläther ist bei Gegenwart von Zink nicht durchführbar. Die unter Verwendung von radioaktivem⁶⁵Zn innerhalb weiter Konzentrationsbereiche an Bromwasserstoffsäure und Metallion bestimmten Verteilungskoeffizienten sind relativ groß und entsprechen einer 9%igen Extraktion. Weitere Versuche ergaben die Möglichkeit einer Trennung bei Verwendung von Isopropyläther an Stelle von Diäthyläther. Aus 0,5- bis 6-m Bromwasserstoffsäure ist ZnBr₂ durch Isopropyläther kaum zu extrahieren. Die bei Verwendung von radioaktivem¹¹⁴In als Indikator durchgeführten Untersuchungen der Verteilung von Indiumtribromid durch Aktivitätsmessung ergaben, daß Indium bei einer einzigen Extraktion aus 6-m HBr quantitativ wiedergefunden wird. Die Volumveränderungen der beiden Phasen sind sehr klein gegen die bei Verwendung von Äthyläther.Wegen seiner Einfachheit und großen Wirksamkeit könnte sich dieses Trennungsverfahren gut für die Bestimmung von Indium in metallischem Zink oder Zinkkonzentraten bewähren.

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Résumé L'étude d'une méthode de dosage de 1'indium dans le zinc par radioactivation a nécessité son isolement après irradiation. La technique de séparation qui est basée sur la possibilité d'extraire InBr₃ dans l'éther diéthylique n'est pas applicable en présence du zinc. L'emploi de zinc radioactif⁶⁵Zn dans un vaste domaine de concentrations de l'acide bromhydrique et de l'ion métallique permet de déterminer les coefficients de distribution; ils sont relativement élevés et correspondent à une extraction de 9%. De nouvelles expériences ont montré la possibilité d'effectuer la séparation lorsqu'on remplace l'éther éthylique par l'éther isopropylique. Le pouvoir d'extraction de ce solvant pour ZnBr₂ est négligeable lorsque la concentration en acide bromhydrique est comprise entre 0,5 et 6 M. Lorsqu'on emploie¹¹⁴In comme traceur, les mesures d'activité ont montré, par étude de la distribution du tribromure d'indium que la récupération de 1'indium était quantitative après une seule extraction dans l'acide bromhydrique 6 M. Les variations de volumes des deux phases sont très faibles comparativement à celles qui se produisaient avec l'éther diéthylique comme solvant. Cette méthode de séparation simple et efficace aurait un emploi des plus appropriés pour l'analyse du zinc métallique ou des solutions concentrées de zinc dans lesquelles on doit doser l'indium.

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L. Kosta, on leave from the Institute J. Stefan, Ljubljana, Yugoslavia, expresses his indebtedness to Prof.J. Gillis, Rector of the University of Ghent, for the permission to work in his laboratory and to the Institute J. Stefan for the financial support during this investigation.     

两步液液萃取-固相萃取净化结合高效液相色谱-串联质谱法测定猪肉中11种磺胺类兽药残留

建立了猪肉中11种常见的磺胺类兽药残留的两步液液萃取-固相萃取净化-高效液相色谱-串联质谱（LC-MS/MS）检测方法。猪肉样品经乙酸乙酯（含2%（v/v）甲酸）及丙酮分两步液液萃取，正己烷脱脂，Oasis MCX混合阳离子固相萃取小柱净化，氮吹浓缩，定容，过滤膜后进行高效液相色谱-串联质谱分析。采用多反应监测正离子模式进行检测，以基质校准曲线外标法定量。结果表明，在20~400 μg/L范围内11种磺胺类药物均呈现良好的线性关系（相关系数（r²）≥ 0.99），检出限（LODs）（S/N=3）和定量限（LOQs）（S/N=10）分别为0.1~1.0 μg/kg和0.2~3.0 μg/kg。对阴性猪肉样品，在50、100、200 μg/kg 3个水平下分别进行加标回收试验，测得各待测物的平均回收率为79.3%~105.5%之间，相对标准偏差为1.3%~11.6%（n=6）。该方法比采用一步液液萃取法具有更高的提取效率，同时结合固相萃取净化方法进一步富集目标化合物，降低了基质干扰，提高了检测灵敏度。     

Separation of technetium from rhenium by liquid-liquid extraction with potassium xanthate

A method is described for separating technetium from rhenium in hydrochloric acid medium by liquid-liquid extraction with potassium xanthate and carbon tetrachloride. The effects of the concentration of various acids, concentration of xanthate, different solvents and diverse ions have been investigated.     

Chiral separation by enantioselective liquid-liquid extraction

The literature on enantioselective liquid-liquid extraction (ELLE) spans more than half a century of research. Nonetheless, a comprehensive overview has not appeared during the past few decades. Enantioselective liquid-liquid extraction is a technology of interest for a wide range of chemists and chemical engineers in the fields of fine chemicals, pharmaceuticals, agrochemicals, fragrances and foods. In this review the principles and advances of resolution through enantioselective liquid-liquid extraction are discussed, starting with an introduction on the principles of enantioselective liquid-liquid extraction including host-guest chemistry, extraction and phase transfer mechanisms, and multistage liquid-liquid extraction processing. Then the literature on enantioselective liquid-liquid extraction systems is reviewed, structured on extractant classes. The following extractant classes are considered: crown ether based extractants, metal complexes and metalloids, extractants based on tartrates, and a final section with all other types of chiral extractants.     

Fragment-imprinted microspheres for the extraction of sulfonamides

Fragment-imprinted microspheres (FIMs) were synthesized by suspension polymerization of 4-sulfa-6-chloropyrimidine (the template), methacrylic acid and styrene (the mixed functional monomers), divinylbenzene (the crosslinker), and azobisisobutyronitrile (the initiator). The optimum conditions were obtained by an orthogonal experiment. After removal of the templates, the microspheres serve as a material to fairly specifically bind sulfonamides, the absorption capacity being 6.32 mg g^–1, whereas the absorption by non-imprinted microspheres is 1.68 mg g^?1. A method was worked out for the simultaneous determination of five sulfonamides by solid phase extraction (using the FIMs) coupled to HPLC, and applied to analyze milk samples. The recoveries are within 87.6 and 96.5 %, with relative standard deviations between 1.25 and 2.89 %.

Homogeneous liquid-liquid extraction of trace amounts of mononitrotoluenes from waste water samples

Homogeneous liquid-liquid extraction method was studied based on a phase separation phenomenon in a ternary solvent system. According to this procedure, mononitrotoloenes were extracted by single-phase extraction in a water/methanol/chloroform, homogeneous ternary solvent system. Methanol and chloroform were used as consolute and extraction solvents, respectively. The homogeneous solution was broken by the addition of salt and a cloudy solution was formed. After centrifugation, the fine droplets of the extraction solvent were sedimented in the bottom of the conical test tube. Analysis of the extracts was carried out by gas chromatography. The optimization procedure was performed using Box-Behnken design. The variables involved were: sample and extraction solvent volumes, consolute solvent volume and phase separator reagent concentration. Optimum results were obtained under the following conditions: sample volume of 5 mL, extraction solvent volume of 55 μL, consolute solvent volume of 1 mL and phase separator reagent concentration; 5% (w/v). Under these conditions, the enrichment factors of 354, 311 and 300, dynamic linear ranges of 0.5-500, 1-500 and 1-500 μg L⁻¹, and limit of detections (LODs) of 0.09, 0.09 and 0.1 μg L⁻¹ were obtained for o-nitrotoluene, m-nitrotoluene and p-nitrotoluene, respectively. Finally, the method was successfully applied to the extraction and determination of MNTs in the waste water samples in the range of micrograms per liter with R.S.Ds. < 13.2%.