Homogeneous Liquid-liquid Extraction Research Articles

Homogeneous liquid–liquid extraction method for the selective spectrofluorimetric determination of trace amounts of tryptophan

Twenty-one amino acids were derivatized with fluorescamine (FLA) under basic conditions (pH 9) and the extraction of the amino acid-FLA derivatives was investigated using a homogeneous liquid-liquid extraction with perfluorooctanoic acid (HPFOA) based on phase separation under strongly acidic conditions. Under the optimum concentration conditions for the reagents ([PFOA]T = 3 x 10(-3) mol dm-3, [acetone]T = 3 vol.%, [HCl]T = 1.8 mol dm-3), the concentration factor was approximately 1000-fold (i.e., 30 microliters of the sedimented liquid phase was produced from 33 ml of the homogeneous aqueous solution). The percentage extraction (E) was determined for the 21 amino acid-FLA derivatives; the value for the tryptophan (Trp)-FLA derivative was 80.9%, whereas the other derivatives were not almost extracted (E < 0.4%). The Trp-FLA derivative was selective for the extraction using the homogeneous liquid-liquid extraction method with HPFOA. After the sedimented liquid phase containing Trp-FLA has been placed on a polytetrafluoroethylene filter-paper, the fluorescence intensity was determined using a spectrofluorimeter with filter-paper as the solid-sample holder. The calibration graph of Trp was linear over the range 1.0 x 10(-8)-1.5 x 10(-6) mol dm-3. The relative standard deviation for the central value of the calibration graph was 4.5% (five determinations) and the detection limit (S/N = 3) was 8.9 x 10(-9) mol dm-3. When the proposed method was applied to the highly sensitive spectrofluorimetric determination of Trp in animalin-L syrup, the results were satisfactory.

X-ray fluorescence analysis of trace metal ions following a preconcentration of metal-diethyldithiocarbamate complexes by homogeneous liquid-liquid extraction.

A homogeneous liquid-liquid extraction method for 36 metal ions with diethyldithiocarbamate was studied. As a result, 11 metal ions were extracted as metal-chelates. Under the experimental conditions, the maximum concentration factor was 500 (i.e., 0.1 mL of sedimented liquid phase was produced from 50 mL of aqueous phase). Moreover, the proposed method was utilized as a preconcentration method for X-ray fluorescence analysis of these metals. The recovery of each metal was ca. 97-100%. All calibration curves were linear over the range of 5.0 x 10(-7) mol L-1 to 1.0 x 10(-5) mol L-1. The detection limits were at the 10(-8) mol L-1 levels and the relative standard deviations were below 5% (5 determinations). When the proposed method was used for the determination of contaminants in a synthetic sample (Al-based alloy model) and of components in an Au-Pd alloy, the results were satisfactory.

Determination of Trace Impurities in Graphite and Silicon Carbide by Total Reflection X-ray Fluorescence Spectrometry after Homogeneous Liquid-Liquid Extraction.

Using homogeneous liquid-liquid extraction as a pre-concentration method, a determination orocedure of trace impurities (Fe, Ni and Cu) by total reflection X-ray fluorescence (TXRF) analysis was developed and optimized for graphite and silicon carbide samples. The samples were decomposed by alkali fusion. The residue was dissolved in a mixture of pentadeca-fluorooctanoic acid (PFOA), acetone and water, and the analytes were homogeneously dispersed by the aid of phenanthroline (phen). After phase separation with pH-adjustment, a portion of the sedimented water-immiscible liquid was pipetted on the polyester film that covered a silicon wafer sample-carrier. Then, the droplet was dried in a vacuum and analyzed by TXRF. Analytical values in the sub-ppm or ppm level were well agreed with the certified values of the standard samples or the values observed by ICP-OES for a few samples.

三成分系均一液液抽出‐ＧＣ／ＭＳ法によるクロロフェノール類の定量

The simple pretreatment-GC/MS method for chlorophenol(CP) derivatives was developed using the homogeneous liquid-liquid extraction in water/pyridine/ethyl chloroacetate ternary component system. The proposed method was performed all process of pretreatment within 15minutes. The determination limits(S/N=3) of each CP derivative were the range of 0.2-2.1μgL-1 in the volume ratio 1000(i.e. water phase: 50mL→organic phase: 50μL). Ten kinds of CP derivative were completely separated and were able to determine except 2, 5CP and 2, 6CP.

Homogeneous liquid-liquid extraction using perfluorooctanesulfonic acid and calcium and its application to the separation and recovery of vitamin B12

A new phase separation phenomenon was observed in which the perfluorooctanesulfonate ion (PFOS−) and calcium ion form an ion-pair associator and the sedimented liquid phase occurs from the homogeneous aqueous solution. This phenomenon was observed in the neutral pH region at room temperature (25 °C). The optimum concentration conditions for the reagents were [PFOS−]T = 7 × 10−3 mol dm-3 and [Ca2+]T = 1.1 mol dm-3. When these findings were applied to the homogeneous liquid–liquid extraction of vitamin B12, the extraction percentage (E) was 83% and the concentration ratio (ie Va/Vs, where Va is the volume of the aqueous phase and Vs is the volume of the sedimented liquid phase) was a maximum of 149. The recovery of vitamin B12 was achieved by adding the propanol–acetone (20 : 80 v/v%) mixed solvent to the sedimented liquid phase; the vitamin B12 precipitated and was filtered. Both the PFOS− and Ca2+ were removed by dissolution in the mixed solvent. The recovery percentage of vitamin B12 was 78%. © 1999 Society of Chemical Industry

Homogeneous liquid-liquid extraction method for some kinds of high-valence metal ions using desferrioxamine B.

Homogeneous liquid-liquid extraction method for some kinds of high-valence metal ions using desferrioxamine B.

Homogeneous liquid-liquid extraction method for spectrofluorimetric determination of chlorophyll a

A new homogeneous liquid-liquid extraction using a fluorocarbon ionic surfactant, Zonyl FSA (FSA), having a diethylthioether group as a spacer between the perfluoroalkyl group and carboxyl group has been developed. In this FSA method, the phase separation phenomena were observed at mild pH (below pH 6). Moreover, by using this extraction method as a preconcentration, a highly sensitive spectrofluorometric determination of chlorophyll a was established. The results for the standard chlorophyll a were as follows. The concentration factor ( V w/ V o) was 200 (water phase, V w, 20 cm 3, water-immiscible phase, V o, 100 μl), the distribution ratio, log D, was 4.85, the extraction percentage, E, was 99.7%, and the procedure time was ≈ 30 min. The calibration curve was linear in the concentration range 2 × 10 −11−3 × 10 −7 mol dm −3 and the detection limit ( S/ N=3) was 1 × 10 −11 mol dm −3. The relative standard deviation was 0.72% for 10 −8 mol dm −3 (five determinations).

A Novel Homogeneous Liquid-liquid Extraction Based on Three-phase Formation with Perfluorosurfactant and Amine Compounds

Abstract A new type of three-phase separation phenomenon was found by the charge neutralization of perfluorooctanate ion {PFOA−, CF3(CF2)6-COO−} with amylammonium ion (R-N+H3). For example, a three-phase system was formed at pH = 6.8 and [PFOA]T/[amine]T = 0.5. The partition behaviors of solutes such as water-soluble porphyrin and compounds in vivo into each liquid phase were examined.

Homogeneous liquid-liquid extraction by pH dependent phase separation with a fluorocarbon ionic surfactant and its application to the preconcentration of porphyrin compounds

Aqueous perfluorooctanoate (PFOA−) solution of water-miscible organic solvent (SOLV), such as dioxane and acetone, was separated into two immiscible phases reversibly by charge neutralization of PFOA− ion with proton (H+) (pKa value of HPFOA was 1.01, atI = 0.1, 20 °C). The transparent heavier phase, in which HPFOA was concentrated quantitatively, consisted of three components in the molar ratio of HPFOA∶SOLV∶H2O = 1∶4.0∶6.6 for acetone system, and 1∶0.47∶1.9 for dioxane system, respectively. This separation provides a new homogeneous liquid-liquid extraction method, which can be successfully applied to the ultra-high preconcentration of water-soluble porphyrin compounds: 104-fold concentration was achieved within 20 min.

Homogeneous Liquid-Liquid Extraction of Uranium from Fission Products

Homogeneous Liquid-Liquid Extraction of Uranium from Fission Products

Homogeneous liquid-liquid extraction of metal thenoyltrifluoroacetonates

Homogeneous liquid-liquid extraction of metal thenoyltrifluoroacetonates

Homogeneous liquid-liquid extraction method. Extraction of iron(III) thenoyltrifluoroacetonate by propylene carbonate

Homogeneous liquid-liquid extraction method. Extraction of iron(III) thenoyltrifluoroacetonate by propylene carbonate

Homogeneous liquid-liquid extraction method

A new homogeneous liquid-liquid extraction method was applied to the extraction of molybdenum (VI). This method is based on the high solubility of propylene carbonate in water at higher temperature and is characteristic in taking once the state of a uniform solution consisted of water and the organic solvent during the procedure. Equal volume of warmed propylene carbonate was added to 10ml of 1mM molybdate solution of pH 2.5 adjusted with hydrochloric acid in a stoppered centrifuge tube on a water bath warmed above 70°C. After making a uniform solution by shaking the mixture gently twice or thrice, the solution was cooled and centrifuged to separate two layers. As much as 97% of molybdenum (VI) was extracted into propylene carbonate by a single process. This method is useful especially for the extraction of compounds with slower formation rate, for instance, the metal β-diketonates.