Presence Of Trioctylphosphine Oxide Research Articles

A New Extraction System Based on Isopropyl Salicylate and Trioctylphosphine Oxide for Separating Alkali Metals.

It was established that isopropyl salicylate can be used similarly to 1,3-diketones as a key component for a new efficient extraction system for selective separation of alkali metal cations. According to DFT modeling of complexes of isopropyl salicylate and 1,3-diketone with alkali metal cations (Li+, Na+, K+), six-membered metallacycles are formed whose stability decreases along the series Li > Na > K, which results in the observed enhanced affinity to lithium. The extraction ability of isopropyl salicylate is manifested in the presence of trioctylphosphine oxide (TOPO). The newly obtained complexes of isopropyl salicylate with alkali metal cations as well as their extracts in a mixture with TOPO are characterized by means of FT-IR, Raman, and NMR spectroscopy. The probable structure of the extracted lithium complex is presumed and the role of TOPO in the extraction process is investigated in detail. Extraction experiments showed extremely high separation coefficients for Li/Na and Li/K pairs in the extraction from a model multi-component solution.

Cobalt‐Catalyzed Dehydrogenative Coupling of Amines into Imines

Primary amines have been subjected to an acceptorless dehydrogenative homo‐ and heterocoupling into imines with a cobalt catalyst. The catalytically active species are composed of cobalt nanoparticles, which are generated in situ by heating Co2(CO)8 in the presence of trioctylphosphine oxide as a surfactant. The nanoparticles have been characterized by transmission electron microscopy where the image showed spherical and small particles with a narrow size distribution. The catalyst can be recovered and used again with essentially no effect on the yield. The catalyst can also be used for the dehydrogenative coupling of alcohols and amines into imines.

DETERMINATION OF THE AGING TIME OF COGNACS USING A LUMINESCENT SENSOR BASED ON THE TERBIUM(ІІІ) COMPLEX

The possibility of identification of the maturation time (age) marker of cognac – gallic acid – in cognac using a terbium ion-based (III) luminescent sensor is shown. Gallic acid was isolated from cognac by thin layer chromatography on Sorbfil plates; the sample volume applied onto the plate was 1 µL. It was found that acidic systems, such as ethyl acetate : acetic acid in a ratio of 95: 5 and benzene : methanol : acetic acid (100: 5: 1) are best eluting; the latter was selected for the test. A solid-phase sensitized terbium ion luminescence (III) with gallic acid was used as an analytical response. It was established that surface active, as well as a number of donator active substances do not affect the intensity of the luminescence of the complex. An increased intensity of luminescence of the sorbate complex is recorded in the presence of a donor-active additive, trioctylphosphine oxide (TOPO). Analysis of the luminescence spectra and the excitation of the sorbates of the complex in the presence of TOPO allowed concluding that its molecule is not part of the internal sphere of the complex, but play a role of water repellent, protecting from water molecules which deactivate luminescence, which increases the intensity of luminescence. The maximum concentration of terbium ions (ІІІ) and TOPO in the developing solution is 10-3 mol/l. A 4% aqueous hexamine solution was used to achieve the optimal pH value (6.5-7.8) in a developing solution. The luminescence is excited at λ excit. = 365 nm, the intensity of luminescence of terbium ions (III) is recorded at λ em. = 545 nm. Gallic acid is identified according to the calibration curve. A simple and reliable technique has been developed for identification of the age marker of cognac – gallic acid – in different brands and various maturation periods of cognac. The correctness of the results obtained was verified by the spike test. The relative standard deviation is (Sr) 5.2–7.0%. The detection limit of gallic acid is 0.002 μg/ml.

Improving the Stability and Size Tunability of Cesium Lead Halide Perovskite Nanocrystals Using Trioctylphosphine Oxide as the Capping Ligand.

Recently, all-inorganic cesium lead halide (CsPbX3, X = Cl, Br, and I) nanocrystals (NCs) have drawn wide attention because of their excellent optoelectronic properties and potential applications. However, one of the most significant challenges of such NCs is their low stability against protonic solvents. In this work, we demonstrate that by incorporating a highly branched capping ligand, trioctylphosphine oxide (TOPO), into the traditional oleic acid/oleylamine system, monodisperse CsPbX3 NCs with excellent optoelectronic properties can be achieved at elevated temperatures (up to 260 °C). The size of such NCs can be varied in a relatively wide range. The capping of TOPO on NCs has been verified through Fourier transform infrared spectroscopy measurement. More importantly, the presence of TOPO can dramatically improve the stability of CsPbX3 NCs against ethanol treatment. After ethanol treatment for 100 min, the emission intensity of the TOPO-capped sample dropped only 5%, whereas that of non-TOPO-capped NCs dropped up to 86%. This work may shed some light on the preparation and application of CsPbX3 NCs with higher stability.

Size Control of Alloyed Cu‐In‐Zn‐S Nanoflowers

Uniform, alloyed Cu‐In‐Zn‐S nanoflowers with sizes of 11.5 ± 2.1 nm and 31 ± 5 nm composed of aggregated 4.1 nm and 5.6 nm primary crystallites, respectively, were obtained in a one‐pot, heat‐up reaction between copper, indium, and zinc acetate with tert‐dodecanethiol in the presence of trioctylphosphine oxide. Larger aggregates were obtained by diluting tert‐dodecanethiol with oleylamine, which lowered the reactivity of the indium and zinc precursors and led to the formation of copper rich particles. The thermal decomposition of tert‐dodecanethiol stabilizing the primary crystallites induced their agglomeration, while the presence of trioctylphosphine oxide on the surface of the nanoflowers provided them with colloidal stability and prevented them from further aggregation.

Highly Selective Synergism for the Extraction of Lanthanoid(III) Ions with β-Diketones and Trioctylphosphine Oxide in an Ionic Liquid

Selective synergism for the extraction of lanthanoids(III) (Ln) with β-diketones such as 2-thenoyltrifluoroacetone, 2-naphthoyltrifluoroacetone, and benzoylacetone has been investigated in the presence of trioctylphosphine oxide as a hydrophobic neutral ligand in 1-butyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide as an ionic liquid. The extractability of heavier Ln was remarkably enhanced, resulting in a significant improvement in the separation of Ln. It was found that the present synergism is ascribed to the formation of cationic ternary complexes, followed by ion exchange into the ionic liquid.

Synthesis and nonlinear optical switching of Bi2S3 nanorods and enhancement in the NLO response of Bi2S3@Au nanorod-composites

Organic solvent dispersible bismuth(III) sulfide (Bi2S3) nanorods were prepared by the chemical decomposition of tris(monothiobenzoato) bismuth(III), [Bi(SCOPh)3] as a single molecular precursor in the presence of trioctylphosphine oxide (TOPO) and 1-dodecanethiol (DdT). The rod surfaces of the as-prepared Bi2S3 nanorods were attached to Au nanoparticles (NPs) via direct reduction of KAuCl4·2H2O in the presence of octylamine (OTA) and oleic acid (OA). The attachment of the Au NPs onto the Bi2S3 rod surfaces was found to be relatively stable. The prepared samples (both Bi2S3 and Bi2S3@Au) were characterized by powder X-ray diffraction (PXRD), high resolution transmission electron microscopy (HRTEM), energy dispersive X-ray (EDX) analysis and UV-vis spectroscopy. Their nonlinear-absorption (NLA) responses were studied using laser pulses at 532, 780 and 1064 nm, and the observed enhancement in the NLO response of Bi2S3@Au was discussed. Optical switching behaviour was observed at all the wavelengths.

Synthesis and Characterisation of Silver Nanoparticles in Different Medium

Silver nanoparticles were synthesized in different alcoholic medium such as ethylene glycol and n-butyl alcohol by solvothermal method. The nanoparticles have been successfully synthesized by reducing silver nitrate with the above solvents in the presence of trioctyl phosphine oxide (TOPO) as the capping agent at room temperature for 1 h. Electron microscopy, X-ray diffraction, and absorption spectra have been used to investigate the products, and the mechanism is proposed to interpret the controlled synthesis of the products. The results indicate that this approach provides a versatile route to prepare silver nanowires and nanoparticles with controllable diameters. The formation of nano products by this method is rapid, simple and stable.

Synergistic Effect in the Solvent Extraction and Separation of Lanthanoids by 4-(4-Fluorobenzoyl)-3-methyl-1-phenyl-pyrazol-5-one in the Presence of Monofunctional Neutral Organophosphorus Extractants

4-(4-Fluorobenzoyl)-3-methyl-1-phenyl-pyrazol-5-one (HL) has been synthesized and its complexation properties in solution were examined. Mixed ligand chelate extraction of trivalent lanthanoids (La, Nd, Eu, Ho, and Lu) from chloride medium at constant ionic strength μ = 0.1 into C6H6 with HL in combination with one of the three phosphine oxide compounds trioctylphosphine oxide (TOPO), tributylphosphine oxide (TBPO), or triphenylphosphine oxide (TPPO) as well as with tributylphosphate (TBP) was studied. The interaction between the extractants in C6H6-d6 has been studied by 1H, 13C, and 31P NMR spectroscopy and its influence on the synergistic extraction of Nd(III) ion has been investigated. The composition of the extracted species was established as LnL3·HL with HL alone and as LnL3·2S in the presence of TOPO, TPPO, and TBP or LnL3·S with the mixture of HL–TBPO. A synergic effect up to 106 was observed for the extraction of the above-mentioned lanthanoid ions with binary mixtures of extractants. The change of the synergistic agent causes a significant increase of the KL,S values. The parameters of the extraction process were determined and the separation factors were calculated.

Formation mechanisms of Ni2P nanocrystals using XANES and EXAFS spectroscopy

Abstract Ni2P nanocrystals have been synthesized by a ligand stabilization method with adopting nickel acetylacetonate (Ni(acac)2) as a nickel precursor and trioctylphosphine (TOP) as a phosphorous precursor in the presence of trioctylphosphine oxide (TOPO) as a coordinating solvent. In order to better understand the formation of Ni2P nanocrystals, various synthetic routes were employed with varying the mixing order of TOP or TOPO with Ni(acac)2 in the complexation and nucleation steps, and the phosphidation temperatures of Ni–TOP solution in TOPO. In all cases the formation of Ni2P nanocrystals having an average size in range of 5–11 nm was achieved, but with slightly larger particle distribution of ca. 11 nm being observed for the case where the TOP was injected after a nucleation of Ni–TOPO was formed. In particular, XAFS techniques of EXAXS and XANES which are effective to characterize either amorphous or crystalline materials were applied to examine the structural and electrical properties of the precursor, intermediate and final materials. This led to elucidate the role and the effect of TOP and TOPO on the formation of Ni2P nanocrystals. It is concluded that the formation of Ni2P nanocrystals proceeds through three consecutive steps of complexation, nucleation and phosphidation. In phosphidation, TOP works as a reducing agent on the Ni precursor as well as a phosphorous source through the cleavage of P–C bonds.

A Nonaqueous Approach to the Preparation of Iron Phosphide Nanowires

Previous preparation of iron phosphide nanowires usually employed toxic and unstable iron carbonyl compounds as precursor. In this study, we demonstrate that iron phosphide nanowires can be synthesized via a facile nonaqueous chemical route that utilizes a commonly available iron precursor, iron (III) acetylacetonate. In the synthesis, trioctylphosphine (TOP) and trioctylphosphine oxide (TOPO) have been used as surfactants, and oleylamine has been used as solvent. The crystalline structure and morphology of the as-synthesized products were characterized by powder X-ray diffraction (XRD) and transmission electron microscopy (TEM). The obtained iron phosphide nanowires have a typical width of ~16 nm and a length of several hundred nanometers. Structural and compositional characterization reveals a hexagonal Fe2P crystalline phase. The morphology of as-synthesized products is greatly influenced by the ratio of TOP/TOPO. The presence of TOPO has been found to be essential for the growth of high-quality iron phosphide nanowires. Magnetic measurements reveal ferromagnetic characteristics, and hysteresis behaviors below the blocking temperature have been observed.

Phase-Selective Synthesis of CuInS2 Nanocrystals

Single-source precursor, [(Ph3P)CuIn(SC{O}Ph)4] (1), and dual-source precursors, [Cu(SC{O}Ph)] (2) and [In(bipy)(SC{O}Ph)3] (3), have been used to obtain the monodispersed wurtzite (hexagonal) and zincblende (also called sphalerite, cubic) phases of copper indium sulfide nanocrystals (CIS NCs). The NCs have been characterized by X-ray powder diffraction patterns, transmission electron microscopy, selected area electron diffraction, and energy-dispersive X-ray analysis. It is shown that the relative ratios of surfactants have influence on the formation of the wurtzite or zincblende phase of CIS. Moreover, the reaction temperature plays a role in stabilizing the high-temperature metastable zincblende cubic phase at room temperature. In the presence of trioctylphosphine oxide (TOPO) and dodecanethiol (DT), 1 generates the wurtzite phase of CIS when the reaction temperature is below 275 °C, but above this temperature the obtained product belongs to zincblende (cubic). The morphology of the CIS also changes from nanoplates to nanoparticles when it undergoes phase transformation. In the wurtzite phase, monodispersed nanoplates are formed at 175 °C and nanorods (NRs) produced at 250 °C along with the plates. Wurtzite and zincblende CIS nanocrystals exhibit intense emission in the ultraviolet region and weak emission in the visible region. The nonlinear optical (NLO) properties of the CIS NCs have also been characterized with femtosecond laser pulses at a wavelength of 780 nm.

Formation of coordination compounds in gadolinium-loaded liquid organic scintillators (GdLS): Use of mixed-ligand gadolinium complexes in GdLS preparation

The formation of coordination compounds between gadolinium 2-methylvalerate (Gd(2MVA)3) and trioctylphosphine oxide (TOPO) in a gadolinium-loaded liquid scintillator (GdLS) solution was studied by MALDI-TOF MS. The most abundant gadolinium-containing compound in the GdLS solution in the presence of TOPO is the monomer complex Gd(2MVA)3 · (TOPO)2. In the absence of TOPO, the solution contains only Gd n (2MVA)3n (n = 2–5) association species. Therefore, TOPO prevents carboxylate polymerization in the solution and can be used as a stabilizer of the gadolinium compounds in GdLS. The existence of the Gd(2MVA)3 · TOPO complex is confirmed by IR spectroscopy. The possibility of coordination between Gd(2MVA)3 and 2,5-diphenyloxazole (PPO), the most common scintillation admixture, has been investigated. No complexes between Gd(2MVA)3 and PPO have been detected by MALDI-TOF MS in the scintillator solution. IR spectroscopic data also do not provide any unambiguous indication of coordination between Gd(2MVA)3 and PPO.

Chloroform- and Water-Soluble Sol–Gel Derived $\hbox{Eu}^{+++}/\hbox{Y}_{{\rm 2}}\hbox{O}_{{\rm 3}}$ (Red) and $\hbox{Tb}^{+++}/\hbox{Y}_{{\rm 2}}\hbox{O}_{{\rm 3}}$ (Green) Nanophosphors: Synthesis, Characterization, and Surface Modification

Eu <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">+++</sup> and Tb <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">+++</sup> ions have been incorporated into nanodimensional yttrium oxide host matrices via a sol-gel process using Y <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">5</sub> O(OPr <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">i</sup> ) <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">13</sub> as precursor (OPr <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">i</sup> = isopropoxy). The as-synthesized white powders have been annealed at different temperatures. Photoluminescence (PL) spectroscopy and X-ray diffraction (XRD) have been used as tools for documenting the characteristics of these powders. For Eu <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">+++</sup> -doped powders, a comparison of the Eu <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">+++</sup> , <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">5</sup> D <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0</sub> rarr <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">7</sup> F <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">1</sub> , and <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">5</sup> D <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0</sub> rarr <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">7</sup> F <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> peak intensities in the emission spectra reveals that the dopant ions are occupying unsymmetrical sites in the host yttrium oxide in all the samples. For Tb <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">+++</sup> -doped powders, the characteristic terbium <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">5</sup> D <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> rarr <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">7</sup> F <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">n</sub> and <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">5</sup> Drarr <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">7</sup> F <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">n</sub> ( <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">n</i> = 2-6) transitions were visible only in the samples that had been annealed above 500degC. Samples of the doped particle powders were suspended in chloroform by fragmenting the powder with and without sonification under the presence of trioctylphosphine oxide, or a mixture of oleic acid and dioctyl ether. The resulting clear colorless (for Eu <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">+++</sup> ) and light green translucent (for Tb <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">+++</sup> ) solutions of the suspended particles showed red and green luminescence upon UV excitation, respectively. In addition, suspension in water has been achieved by fragmenting the powder in the presence of dichloroacetic acid. Transmission electron micrograph investigation of the soluble particles shows single dispersed particles along with agglomerates. The changes in the luminescence due to fragmentation of the particle powder and due the influence of the surfactant of the suspended colloidal particles are discussed.

Optical memory based on photo-activated fluorescence of core/shell CdSe/CdS quantum dots embedded in poly(butylmethacrylate)

This work presents the observation of a photo-activated fluorescence from core/shell quantum dots of CdSe/CdS incorporated in a poly(butylmethacrylate) matrix. Upon illumination with UV-light, the intensity of fluorescence from the quantum dots increases as seen by naked eyes at ambient conditions. This allows its utilization in optical memory media based on thin films of CdSe/CdS polymer nanocomposites suitable for practical application. The quantum dots are synthesized by the hot-injection method and embedded in poly(butylmethacrylate) matrix by radical polymerization with 1,1′-azobis-(cyclohexanecarbonitrile). The fluorescence of quantum dots quenched during the polymerization process, but appeared again after illumination of the nanocomposite material with UV-light. The fluorescence properties of quantum dots are governed by the presence of trioctylphosphine oxide in the matrix, which allows control of the optical memory effect.

Self-cleaning anatase nanorods: photocatalytic removal of structure directing agents and subsequent surface modification

Anatase nanorods were synthesised via the non-hydrolytic condensation of TiCl4 and Ti(OPr)4 in the presence of trioctylphosphine oxide and dodecylamine as structure directing agents, to produce rod-like particles approximately 5 nm in diameter and 15 nm in length. The crystal structure was confirmed as pure anatase by Raman spectroscopy and X-ray diffraction. The as-prepared nanorods can be dispersed in organic solvents as a result of hydrophobic surface functionalities imparted during the synthesis. Subjecting nanorod suspensions in CHCl3–water mixtures to UV irradiation leads to complete photocatalytic removal of surfactants from the TiO2 surface, enabling, in turn, transfer of the nanorods into the aqueous phase. Quaternary ammonium hydroxides were used to stabilise optically clear aqueous suspensions, through a combination of electrostatic and steric repulsion between particles; dispersions of individual nanorods are a prerequisite for many technological applications. Once ‘stripped’ of their organic ligands, the nanorods can be further functionalised using, for example, aminopropyltriethoxysilane to modify the isoelectric point, dispersibility, or photocatalytic activity; these effects are demonstrated by electrophoretic and dye degradation experiments.

Synthesis and self-organization of Au nanoparticles

Monodisperse (diameter 10 nm) Au nanoparticles have been synthesized by the reduction ofAuCl3 at high temperatures, in commercial oleyl amine, in the presence of tri-octyl phosphineoxide (TOPO). The oleyl amine molecule has multiple roles, acting as high-boiling-pointsolvent, capping agent and reducing agent. The Au nanocrystalline particles have beenstudied by powder x-ray diffraction (XRD) and transmission electron microscopy (TEM).The nanoparticles can disperse well in non-polar solvents such as hexane, toluene andchloroform. The as-received Au nanoparticles, capped with the alkylamine-TOPOmolecules, form two-dimensional superlattices via solvent evaporation. Moreover, they canbe converted into a water-soluble derivative via a simple procedure based on the formationof a physisorbed layer of an ionic (cationic or anionic) surfactant around the cappedsurface. The charged particles can assemble in aqueous solution into three-dimensionalstructures via electrostatic interactions.

Reductive thermolysis of a heterocyclic precursor: a convenient method for preparingluminescent, surfactant-stabilized silicon nanoparticles

A convenient one-step synthesis of silicon nanoparticles from thermal reduction of-di-tert-butyl-1, 3-diaza-2, 2-dichloro-2-silacyclopentane in the presence of trioctylphosphineoxide and Li metal is discussed. Transmission electron microscopy, energy dispersive x-rayanalysis, UV/visible and IR spectroscopy, fluorescence spectrophotometry and nuclearmagnetic resonance were employed to characterize the nanoparticles with an average size of5.2 ± 1.2 nm.

Chemical Equilibrium and Synergism for Solvent Extraction of Trace Lithium with Thenoyltrifluoroacetone in the Presence of Trioctylphosphine Oxide

Equilibria and applications of a synergistic extraction were studied for the determination of a trace lithium by using thenoyltrifluoroacetone (TTA) and trioctylphosphine oxide (TOPO) as ligands. Several equations were derived for the extraction of lithium into m-xylene as a phase of Li-TTA·mTOPO adduct. Distribution coefficients and extraction constant were determined together with a stability constant of the adduct. The adduct was quantitatively extracted from the basic solution of higher than pH 9 by shaking for 30 minutes. m-Xylene was selected as an optimum solvent by comparing the extraction efficiency among several kinds of organic solvents. The stability constant (<TEX>${\Beta}_2$</TEX>) for Li-TTA/2TOPO was 150 times higher than Li-TTA/TOPO. The distribution coefficient of Li-TTA/2TOPO into m-xylene was 9.12 and the logarithmic extraction constant (log <TEX>$K_{ex}$</TEX>) was 6.76. Trace lithium of sub-ppm level in seawater samples could be determined under modified conditions and a detection limit equivalent to 3 times standard deviation for background absorption was 0.42 ng/mL.

Investigation of the luminescent properties of terbium–anthranilate complexes and application to the determination of anthranilic acid derivatives in aqueous solutions

The luminescent properties of terbium complexes with furosemide (FR), flufenamic (FF) acid, tolfenamic (TF) acid and mefenamic (MF) acid have been investigated in aqueous solutions. For all four compounds, complexation occurs when the carboxylic acid of the aminobenzoic group is dissociated and is greatly favoured in the presence of trioctylphosphine oxide as co-ligand and Triton X-100 as surfactant. Under optimum conditions, luminescence of the lanthanide ion is efficiently sensitised and the lifetime of the 5 D 4 resonance level of terbium in the complex is ranging between 1 and 1.9 ms, against 0.4 ms for the aqua ion. The sensitivity of the method for the determination of anthranilic acid derivatives is improved by one to two orders of magnitude with respect to that achieved using native fluorescence or terbium-sensitised luminescence in methanol. The limits of detection are 2×10 −10, 5×10 −10 and 2×10 −9 mol l −1 for flufenamic acid, furosemide and tolfenamic acid, and mefenamic acid, respectively, with within-run RSD values of less than 1%. The method has been applied to the determination of flufenamic acid in spiked calf sera with and without sample pretreatment. Depending on the method and the analyte concentration, the recovery was ranging between 83 and 113% and the lowest concentration attainable in serum samples was close to 1×10 −7 mol l −1.