Chemically-modified activated carbon with ethylenediamine for selective solid-phase extraction and preconcentration of metal ions

A new method that utilizes ethylenediamine-modified activated carbon (AC-EDA) as a solid-phase extractant has been developed for simultaneous preconcentration of trace Cr(III), Fe(III), Hg(II) and Pb(II) prior to the measurement by inductively coupled plasma optical emission spectrometry (ICP-OES). The new sorbent was prepared by oxidative surface modification. Experimental conditions for effective adsorption of trace levels of Cr(III), Fe(III), Hg(II) and Pb(II) were optimized with respect to different experimental parameters using batch and column procedures in detail. The optimum pH value for the separation of metal ions simultaneously on the new sorbent was 4.0. Complete elution of absorbed metal ions from the sorbent surface was carried out using 3.0 mL of 2% (%w/w) thiourea and 0.5 mol L⁻¹ HCl solution. Common coexisting ions did not interfere with the separation and determination of target metal ions. The maximum static adsorption capacity of the sorbent at optimum conditions was found to be 39.4, 28.9, 60.5 and 49.9 mg g⁻¹ for Cr(III), Fe(III), Hg(II) and Pb(II), respectively. The time for 94% adsorption of target metal ions was less than 2 min. The detection limits of the method was found to be 0.28, 0.22, 0.09 and 0.17 ng mL⁻¹ for Cr(III), Fe(III), Hg(II) and Pb(II), respectively. The precision (R.S.D.) of the method was lower 4.0% (n = 8). The prepared sorbent as solid-phase extractant was successfully applied for the preconcentration of trace Cr(III), Fe(III), Hg(II) and Pb(II) in natural and certified samples with satisfactory results.     

Silica gel modified with 1-(2-aminoethyl)-3-phenylurea for selective solid-phase extraction and preconcentration of Sc(III) from environmental samples

A new method that utilizes 1-(2-aminoethyl)-3-phenylurea-modified silica gel as a solid-phase extractant has been developed for preconcentration of trace Sc(III) prior to the measurement by inductively coupled plasma atomic emission spectrometry (ICP-AES). Experimental conditions for effective adsorption of trace level of Sc(III) were optimized using batch and column procedures in detail. The optimum pH value for the separation of Sc(III) on the new sorbent was 4 and complete elution of Sc(III) from the sorbent surface was carried out using 1.0 mL of 0.1 mol L⁻¹ HCl. Common coexisting ions did not interfere with the separation and determination of the analyte. The maximum static adsorption capacity of the sorbent at optimum conditions was found to be 32.5 mg g⁻¹ while the time of 95% adsorption was less than 2 min. The detection limit of present method was found to be 0.091 μg g⁻¹, and the relative standard deviation (RSD) was lower than 3.0% (n = 8). The method was successfully applied for the preconcentration of trace Sc(III) in the environmental samples with satisfactory results.     

Chemically modified attapulgite with asparagine for selective solid-phase extraction and preconcentration of Fe(III) from environmental samples

A new method that utilizes asparagine modified attapulgite as a solid phase extractant has been developed for preconcentration of trace Fe(III) prior to the measurement by inductively coupled plasma optical emission spectrometry. Characterization of the surface modification was performed on the basis of Fourier transform infrared spectra. The separation/preconcentration conditions of the analyte were investigated, including the pH value, the shaking time, the sample ?ow rate and volume, the elution condition and the interfering ions. At pH 4, the new adsorbent had relatively high capacity and enrichment factor compared to other methods reported so far. The adsorbed Fe(III) was quantitatively eluted by 2 mL of 0.5 mol L⁻¹ HCl. Common coexisting ions did not interfere with the separation. The detection limit of the method was 0.19 μg L⁻¹. The relative standard deviation was 3.4% (n = 8) which indicated that the method had good precision for the analysis of trace Fe(III) in solution samples. The method was validated using two certified reference materials and has been applied for the determination of trace Fe(III) in biological and natural water samples with satisfactory results.     

Simultaneous determination of seven metal ions in water samples by solid-phase extraction on polyacrylonitrile activated carbon fibres

A new solid-phase extraction method utilising polyacrylonitrile activated carbon fibres (PAN-ACFs) as adsorbent was developed for the preconcentration of trace metal ions prior to their determination by inductively coupled plasma optical emission spectrometry (ICP-OES). The PAN-ACFs oxidised with nitric acid were characterised by FT-IR, XRD, SEM and BET analysis. Then the resulting PAN-ACFs were used as solid-phase adsorbent for simultaneously determination of trace Al(III), Be(II), Bi(III), Cr(III), Cu(II), Fe(III) and Pb(II) ions in aqueous solutions. The influences of the analytical parameters on the recoveries of the studied ions were investigated. The optimum experimental conditions of the proposed method were pH: 6.0; eluent concentration and volume: 3.0 mL of 1.5 mol L^?1 nitric acid; flow rates of sample and eluent solution: 1.5 mL min^?1. The preconcentration factors were found to be 67 for Al(III), Bi(III); 83 for Cr(III), Cu(II), Fe(III) and 50 for Be(II), Pb(II). The precision of this method was in range of 1.5%~3.5% and the detection limit of this metal ions was between 0.06~1.50 μg L^?1. The developed method was validated by the analysis of a certified reference sample and successfully applied to the determination of trace metal ions in water samples with satisfactory results.     

Highly efficient adsorbing noble metal ions by 3,4-dihydroxycinnamic acid-modified activated carbon

A method was established for the preconcentration of trace Au(III), Pd(II) and Pt(IV) by activated carbon modified with 3,4-dihydroxycinnamic acid. The separation and preconcentration conditions of analytes were investigated, such as effects of pH, the contacting time, the sample ?ow rate and volume, the elution condition and the interfering ions. At a pH of 1.0, the maximum static sorption capacity of the sorbent was found to be 374.8, 96.6 and 137.5 mg g^?1 for Au(III), Pd(II) and Pt(IV), respectively. The adsorbed metal ions were effectively eluted with 2.0 mL of 4% thiourea in 0.5 M HCl solution and determined by inductively coupled plasma optical emission spectrometry. The detection limit (3σ) of this method defined by IUPAC was found to be 0.12, 0.18 and 0.32 ?g L^?1 for Au(III), Pd(II) and Pt(IV), respectively. The relative standard deviation (RSD) was lower than 3.0% (n = 8) towards standard solutions. The method has been validated by analysing certified reference materials and successfully applied to the determination of trace Au(III), Pd(II) and Pt(IV) in road sediments samples.     

Multielement Preconcentration and Removal of Trace Metals by Solid-Phase Extraction

ABSTRACT

The solid phase extraction of trace amounts of some metal ions from their mixtures using cation exchanger Dowex 50Wx4, cellulose sorbent with phosphonic acid groups Cellex P, chelating resin Chelex 100 and SIO₂-TPP sorbent which contains porphyrin ligand covalently attached to aminopropyl silica gel was investigated. With respect to multielement preconcentration Cellex P and Chelex 100 seem to be the best sorbents; the recovery test for Al, Be, Cd, Ni, Pb and Zn were > 90%. Additionally, Cellex P appeared to be suitable for enrichment of Co and Mn. Silica-TPP sorbent could be applied as a selective collector for Mo(VI) and V(IV).     

Selective solid-phase extraction of trace cadmium(II) with an ionic imprinted polymer prepared from a dual-ligand monomer

A novel dual-ligand reagent (2Z)-N,N′-bis(2-aminoethylic)but-2-enediamide, was synthesized and applied to prepare metal ion-imprinted polymers (IIPs) materials by ionic imprinted technique for selective solid-phase extraction (SPE) of trace Cd(II) from aqueous solution. In the first step, Cd(II) formed coordination linkage with the two ethylenediamine groups of the synthetic monomer. Then the complex was copolymerized with pentaerythritol triacrylate (crosslinker) in the presence of 2,2′-azobisisobutyronitrile as initiator. Subsequently, the imprinted Cd(II) was completely removed by leaching the dried and powdered materials particles with 0.5 M HCl. The obtained IIPs particles exhibited excellent selectivity for target ion. The distribution ratio (D) values of Cd(II)-IIPs for Cd(II) were greatly larger than that for Cu(II), Zn(II) and Hg(II). The relative selective factor (α_r) values of Cd(II)/Cu(II), Cd(II)/Zn(II) and Cd(II)/Hg(II) were 25.5, 35.3 and 62.1. The maximum static adsorption capacity of the ion-imprinted and non-imprinted sorbent for Cd(II) was 32.56 and 6.30 mg g⁻¹, respectively. Moreover, the times of adsorption equilibration and complete desorption were remarkably short. The prepared Cd(II)-IIPs were shown to be promising for solid-phase extraction coupled with inductively coupled plasma atomic emission spectrometry (ICP-AES) for the determination of trace Cd(II) in real samples. The precision (R.S.D.) and detection limit (3σ) of the method were 2.4% and 0.14 μg L⁻¹, respectively. The column packed with Cd(II)-IIPs was good enough for Cd(II) separation in matrixes containing components with similar chemical behaviour such as Cu(II), Zn(II) and Hg(II).     

Synthesis and applications of surface-grafted Th(IV)-imprinted polymers for selective solid-phase extraction of thorium(IV)

A new functional monomer N-(o-carboxyphenyl)maleamic acid (CPMA) was synthesized and chosen for the preparation of surface-grafted ion-imprinted polymers (IIPs) specific for thorium(IV). Polymerizable double bond was introduced to silica gel surface by amidation reaction between -NH₂ and maleic anhydride. In the ion-imprinting process, thorium(IV) was complexed with the carboxyl groups, then was imprinted in the polymers grafted to the silica gel surface. The imprinted Th(IV) was removed with 3 mol L⁻¹ HCl. The obtained imprinted particles exhibited excellent selectivity and rapid kinetics process for Th(IV). The relatively selective factor (α_r) values of Th(IV)/La(III), Th(IV)/Ce(III), Th(IV)/Nd(III), Th(IV)/U(VI), and Th(IV)/Zr(IV) were 85.7, 88.9, 26.6, 64.4, and 433.8, respectively, which were greater than 1. The precision (R.S.D.), the detection limit (3σ), and the quantification limit (10σ) of the method were 1.9%, 0.51 ng mL⁻¹ and 1.19 ng mL⁻¹, respectively. The prepared IIPs as solid-phase extractants were successfully applied for the preconcentration of trace thorium in natural and certified samples prior to its determination by inductively coupled plasma atomic emission spectrometry (ICP-AES) with satisfactory results.     

Application of low temperature electrothermal vaporization ICP-AES for determination of refractory yttrium with 1-(2-pyridylazo)-2-naphthol as chemical modifier

A low temperature electrothermal vaporization inductively coupled plasma atomic emission spectrometry (ETV-ICP-AES) method was developed for the determination of the refractory yttrium, using 1-(2-pyridylazo)-2-naphthol (PAN) as chemical modifier. The trace yttrium was vaporized as PAN complex into plasma from a graphite furnace at a comparatively low temperature of 1200 °C. The operation conditions were optimized, and the vaporization behavior of Y-PAN chelate and the main factors affecting the determination were investigated in detail. Under the optimized conditions, the detection limit of Y was 0.7 ng ml⁻¹, and the relative standard deviation (R.S.D.) for 0.1 μg ml⁻¹ Y was 4.5% (n=9, v=10 μl). The linear range of calibration curve covered three orders of magnitude. The recommended approach has been applied for analysis of three biological samples with satisfactory results. The accuracy of the method was demonstrated by analyzing two standard reference materials.     

Study on volatilization of ytterbium as 1-(2-pyridylazo)-2-naphthol chelate from electrothermal vaporizer for sample introduction in inductively coupled plasma atomic emission spectrometry

Based on the formation of a volatile 1-(2′-pyridylazo)-2-naphthol (PAN) chelate, a novel method was described for the determination of trace ytterbium by electrothermal vaporization (ETV)-inductively coupled plasma atomic emission spectrometry (ICP-AES). It was found that in the presence of PAN, the trace Yb was quantitatively vaporized from a graphite furnace into ICP at a low temperature of 1100 °C. The main factors affecting the formation and vaporization of the Yb-PAN chelate were investigated in detail. Under the optimized conditions, the 3σ detection limit of Yb for this method was 0.4 ng ml⁻¹ and the relative standard deviation (R.S.D.) for 0.1 μg ml⁻¹ Yb was 3.7% (n=9, v=10 μl). The linear range of calibration spanned three orders of magnitude. The content of Yb in the standard reference material (shrub, GBW 07603) determined by the proposed method was in good agreement with the certified value.     

Amberlite XAD-7 resin impregnated with 2-(1-(4-chlorophenyl)-4,5-diphenyl-1H-imidazol-2yl)-4-nitrophenol for enrichment of metal ions

The Amberlite XAD-7 resin modification was carried out by loading 2-(1-(4-chlorophenyl)-4,5-diphenyl-1H-imidazol-2yl)-4-nitrophenol (CPDPINP). Subsequently, this new sorbent was applied for the enrichment of metal ions such as Cu²⁺, Ni²⁺, Co²⁺ Zn²⁺ and Pb²⁺ ions. The effect of various parameters on their sorption and following recoveries was studied in column procedure. The preconcentrated ions were eluted by appropriate eluent and their contents were quantified by FAAS. This method has preconcentration factor of 150 and enrichment factor in the range of 20.8–29.1. At optimum values of all variables, the proposed method has linear calibration graphs in the range of 0.01 up to 0.29 μg mL⁻¹ with detection limit (3SDb/m, n = 15) between 1.6 and 2.6 ng mL⁻¹. This protocol is usable for successful analysis of Cu²⁺, Ni²⁺, Co²⁺ Zn²⁺ and Pb²⁺ ions in different matrices with reasonable recoveries (>93%) and acceptable relative standard deviation (<4.7%).     

Solid phase extraction of trace Hg(II) on silica gel modified with 2-(2-oxoethyl)hydrazine carbothioamide and determination by ICP-AES

In this work, a new 2-(2-oxoethyl)hydrazine carbothioamide modified silica gel (SG-OHC) sorbent was prepared and applied for preconcentration of trace mercury(II) prior to the measurement by inductively coupled plasma atomic emission spectrometry (ICP-AES). The optimization of some analytical parameters affecting the adsorption of the analyte such as acidity, shaking time, sample flow rate and volume, eluent condition, and interfering substances were investigated. At pH 3, the maximum static adsorption capacity of Hg(II) onto the SG-OHC was 37.5 mg g⁻¹. The quantitative recovery (>95%) of Hg(II) could be obtained using 2 mL of 0.5 mol L⁻¹ HCl and 1% CS(NH₂)₂ solution as eluent. Common coexisting substances did not interfere with the separation of mercury(II) under optimal conditions. The detection limit of present method was 0.10 ng mL⁻¹, and the relative standard deviation (RSD) was lower than 4.0% (n = 8). The prepared sorbent was successfully applied for the preconcentration of trace Hg(II) in certified and water samples with satisfactory results.     

Selective solid-phase extraction of nickel(II) using a surface-imprinted silica gel sorbent

A new Ni(II)-imprinted amino-functionalized silica gel sorbent with excellent selectivity for nickel(II) was prepared by an easy one-step reaction by combining a surface imprinting technique for selective solid-phase extraction (SPE) of trace Ni(II) in water samples prior to its determination by inductively coupled plasma atomic emission spectrometry (ICP-AES). Compared with non-imprinted polymer particles, the ion-imprinted polymers (IIPs) had higher selectivity and adsorption capacity for Ni(II). The maximum static adsorption capacity of the ion-imprinted and non-imprinted sorbent for Ni(II) was 12.61 and 4.25 mg g⁻¹, respectively. The relatively selective factor (α_r) values of Ni(II)/Cu(II), Ni(II)/Co(II), Ni(II)/Zn(II) and Ni(II)/Pd(II) were 45.99, 32.83, 43.79 and 28.36, which were greater than 1. The distribution ratio (D) values of Ni(II)-imprinted polymers for Ni(II) were greatly larger than that for Cu(II), Co(II), Zn(II) and Pd(II). The detection limit (3σ) was 0.16 ng mL⁻¹. The relative standard deviation of the method was 1.48% for eight replicate determinations. The method was validated by analyzing two certified reference materials (GBW 08618 and GBW 08402), the results obtained is in good agreement with standard values. The developed method was also successfully applied to the determination of trace nickel in plants and water samples with satisfactory results.     

Solid-phase extraction of Hg(II) on creatine modified activated carbon and determination by ICP-OES in water samples

A new sorbent was successfully prepared by immobilizing creatine on activated carbon and then used for separation/preconcentration of trace Hg(II) prior to detection by inductively coupled plasma optical emission spectrometry (ICP-OES). Experimental conditions including pH, sample flow rate and volume, eluting variables and tolerance limit of interfering ions were evaluated and established. At pH 1.0 and flow rate of 2.5?mL?min^?1, Hg(II) was adsorbed quantitatively on the column, then quantitatively eluted by 2.0?mL 0.1?mol?L^?1 nitric acid solution; other transition metal ions did not interfere with the determination of Hg(II). An enrichment factor of 100 was obtained for Hg(II). The maximum adsorption capacity was 49.5?mg?g^?1. Under the optimal conditions, the value of the detection limit (3σ) was 0.06?ng?mL^?1, and the relative standard deviation (RSD) calculated was lower than 3.0% (n?=?8). The methodology was validated by analyzing certified reference materials and successfully applied to the determination of trace Hg(II) in natural water samples with satisfactory results.     

Samarium (III) adsorption on bentonite modified with N-(2-hydroxyethyl) ethylenediamine

A new material has been synthesized using dry process to activate bentonite followed by N-(2-hydroxyethyl) ethylenediamine connecting chlorosilane coupling agent. The synthesized new material was characterized by elemental analysis, FT-IR and thermogravimetry which proved that bentonite was successfully modified. The most interesting trait of the new material was its selective adsorption for rare earth elements. A variety of conditions of the new material were investigated for adsorption. The optimal conditions were determined with respect to pH and shaking time. Samarium (Sm) was quantitatively adsorbed at pH 4 and shaking time of 2 min onto the new material. Under these conditions the maximum static adsorption capacity of Sm(III) was found to be 17.7 mg g⁻¹. The adsorbed Sm(III) ion were quantitatively eluted by 2.0 mL 0.1 mol L⁻¹ HCl and 5% CS (NH₂)₂ solution. According to IUPAC definition, the detection limit (3σ) of this method was 0.60 ng mL⁻¹. The relative standard deviation (RSD) under optimum conditions was less than 3% (n = 8). The new material also was applied for the preconcentration of trace Sm(III) in environmental samples with satisfactory results.     

Chemically modified silica gel for selective solid-phase extraction and preconcentration of heavy metal ions

This paper describes our research on the synthesis of the sorbent with chemically bonded ketoimine groups, and, furthermore, using this sorbent in the SPE technique to extract and preconcentrate trace amounts of metal ions in water samples. Surface characteristics of the sorbent were determined by elemental analysis, NMR spectra for the solid phases (²⁹Si CP MAS NMR), and analysis of pore size distribution of the sorbent and nitrogen adsorption-desorption. The newly proposed sorbent with ketoimine groups was applied for the extraction and preconcentration of trace amounts of Cu (II), Cr (III) and Zn (II) ions from the water from a lake, post-industrial water and purified water unburdened back to the lake. The determination of the transition-metal ions was performed on an emission spectroscope with inductively coupled plasma ICP-OES. For the batch method, the optimum pH range for Cu (II) and Cr (III) extraction was equal to 5, and Zn(II)–to 8. All the metal ions can be desorbed from SPE columns with 10?mL of 0.5?mol?HNO₃. The detection limits of the method were found to be 0.7?µg?L^?1 for Cu (II), 0.08?µg?L^?1 for Cr (III), and 0.2?µg?L^?1 for Zn (II), respectively.     

Fabrication and characterization of hexahistidine-tagged protein functionalized multi-walled carbon nanotubes for selective solid-phase extraction of Cu and Ni

Hexahistidine-tagged protein functionalized multi-walled carbon nanotubes (MWCNTs/6His-tagged protein) were prepared and characterized by ultraviolet-visible spectrophotometry and atomic force microscopy. Both static and dynamical adsorption experiments showed that the MWCNTs/6His-tagged protein served as good sorbent for the solid-phase extraction of Cu²⁺ and Ni²⁺. Effective on-line sorption of Cu²⁺ and Ni²⁺ on the MWCNTs/6His-tagged protein packed microcolumn was achieved in a pH range of 3.0-4.5 and 4.5-6.0, respectively. The retained Cu²⁺ and Ni²⁺ were efficiently eluted with 0.2 mol L⁻¹ imidazole-HCl solution for on-line flame atomic absorption spectrometric determination. The MWCNTs/6His-tagged protein exhibited fairly fast kinetics for the sorption of Cu²⁺ and Ni²⁺, and offered up to 20,000 and 1800 times improvement in the tolerable concentrations of co-existing ions over the MWCNTs for solid-phase extraction of Cu²⁺ and Ni²⁺, respectively. On-line solid-phase extraction at a flow rate of 5.0 mL min⁻¹ for 60 s gave an enhancement factor of 29 for Cu²⁺ and 28 for Ni²⁺, a sample throughput of 45 h⁻¹, and a detection limit (3s) of 0.31 μg L⁻¹ for Cu²⁺ and 0.63 μg L⁻¹ for Ni²⁺. The precision for 11 replicate measurements was 2.4% for 10 μg L⁻¹ Cu²⁺, and 2.5% for 15 μg L⁻¹ Ni²⁺.     

Speciation of chromium by selective separation and preconcentration of Cr(III) on an immobilized nanometer titanium dioxide microcolumn

Nanometer titanium dioxide immobilized on silica gel (immobilized nanometer-scale TiO2 particles) was prepared by a sol-gel method and characterized by X-ray diffraction and scanning electron microscopy. The adsorptive behavior of Cr(III) and Cr(VI) on immobilized nanometer TiO2 was assessed. Cr(III) was selectively sorbed on immobilized nanometer TiO2 in the pH range of 7-9, while Cr(VI) was found to remain in solution. A sensitive and selective method has been developed for the speciation of chromium in water samples using an immobilized nanometer TiO2 microcolumn and inductively coupled plasma atomic emission spectrometry. Under optimized conditions (pH 7.0, flow rate 2.0 mL/min), Cr(III) was retained on the column, then eluted with 0.5 mol/L HNO3 and determined by ICP-AES. Total chromium was determined after the reduction of Cr(VI) to Cr(III) by ascorbic acid. The adsorption capacity of immobilized nanometer TiO2 for Cr(III) was found to be 7.04 mg/g. The detection limit for Cr(III) was 0.22 ng/mL and the RSD was 3.5% (n = 11, c = 100 ng/ mL) with an enrichment factor of 50. The proposed method has been applied to the speciation of chromium in water samples with satisfactory results.     

Application of sequential extraction and the ICP-AES method for study of the partitioning of metals in fly ashes

In this work, the original BCR extraction scheme was modified and applied to study the partitioning of metals in fly ashes. In the first step, the water-soluble fraction was investigated here. The next metal fractions were acid-soluble, reducible, and oxidisable. Two kinds of coal fly ash certified reference materials were analysed. Metal concentrations in the extracts were measured by inductively coupled plasma atomic emission spectrometry (ICP-AES). The efficiency of the extraction process for each step was examined. The partitioning of metals between the individual fractions was investigated and is discussed.     

Solvent extraction of rare earth metal ions with 1-(2-pyridylazo)-2-naphthol (PAN)

The formation of the Tm(III) complex with 1-(2-pyridylazo)-2-naphthol (PAN or HL) in aqueous-methanol mixtures (50 and 75%v/v) was studied by a spectrophotometric method. The equilibrium constant for the complexing reaction and the stability constant of the complex TmL ²⁺ were calculated. The solvent extraction of Tm(III) byPAN in carbon tetrachloride from aqueous and aqueous-methanol phase was investigated. The extraction equilibrium constants and two-phase stability constants for the TmL ₃ and the TmL ₃(MeOH)₃ complexes were evaluated. It was confirmed that the addition of methanol to the aqueous phase (above 25%v/v) causes a synergistic effect.

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Extraktion von Ionen der Seltenerdmetalle mit 1-(2-Pyridylazo)-2-naphthol (PAN), 5. Mitt.: Komplexbildung und Gleichgewichtsverteilung von Thulium (III) mitPAN

Zusammenfassung Die Bildung des Komplexes von Tm(III) mit 1-(2-Pyridylazo)-2-naphthol (PAN oder HL) in Wasser-Methanol Mischungen (50 und 75%v/v) wurde mit einer spektrophotometrischen Methode untersucht. Die Gleichgewichtskonstante für die Reaktion der Komplexbildung und die Stabilitätskonstante des Komplexes TmL ²⁺ wurden berechnet. Die Extraktion von Tm(III) mittelsPAN in Kohlenstofftetrachlorid aus Wasser oder Wasser-Methanol wurde untersucht. Die Werte der Extraktionsgleichgewichtskonstante sowie der zweiphasigen Beständigkeitskonstante für die Komplexe TmL ₃ und TmL ₃(MeOH)₃ wurden berechnet. Es wurde festgestellt, daß die Zugabe von Methanol zur wäßrigen Phase (25%v/v) einen synergistischen Effekt hat.