Adsorption of Antimony on Sediments from Typical Water Systems in China: A Comparison of Sb(III) and Sb(V) Pattern

The present work investigated the adsorption of Sb(III) and Sb(V) on five sediment samples (Pearl River, Yangtze River, Yellow River, Yongding River, and Liao River) from typical water systems in China and the adsorption of Sb(V) on Pearl River sediment with different organic carbon (OC) fractions using batch experiments. In order to assess the contributions of sedimentary organic components to the overall adsorption of pentavalent Sb on sediments, one sediment sample was treated by commonly used chemical and physical methods to remove different organic components. Experimental data of Sb(III) and Sb(V) adsorption on five sediments were successfully modeled using the Freundlich (r² > 0.96) isotherm. In general, the sediments with high Fe and Al oxide contents and total organic carbon (TOC) had higher Sb(III) and Sb(V) adsorption than the sediments containing small amounts of Fe and Al oxides and TOC. Dissolved organic carbon (DOC) in sediment promoted the adsorption of Sb(V), and humin fractions and black carbon-like material in sediment had a high affinity for Sb(V).     

Iron(III) and nickel(II) complexes of tetradentate thiosemicarbazones: Synthesis,structure, cytotoxicity,and lipophilicity

Eighteen of the iron(III) and nickel(II) complexes with tetradentate thiosemicarbazidato ligands were synthesized and described, by analytical and spectroscopic methods. Two complexes as an example to the iron and nickel centered ones were crystallographically analyzed to confirm the molecular structures. Cytotoxic effects of the complexes on K562 chronic myeloid leukemia cells were determined by 3‐(4,5‐dimethylthiazol‐2‐yl)‐2,5‐diphenyltetrazolium bromide assay. For comparison, human umbilical vein endothelial cells (HUVECs) was used as a noncancerous cell line. While four of the iron(III) complexes exhibited the antileukemic effect with 50% inhibition of cell growth (IC₅₀) values in the 3.4 to 6.9 μg/mL range on K562 cell line, the nickel(II) complexes showed no significant effect on both cell lines. The complexes Fe4, Fe5, and Fe6, bearing 4‐methoxy substituent exhibited relatively high antiproliferative activity on both cell lines. Complex Fe3 with 3‐methoxy and S‐allyl groups exhibited a selectivity between K562 and HUVEC cells by IC₅₀ values of 6.9 and >10 μg/mL, respectively. Lipophilicity, a key parameter for bioavailability and oral administration, was found in the range of ?0.3 and +1.3 that desired for drug active ingredients. The results were discussed in the context of a structure‐activity relationship.     

Aluminium(III), chromium(III) and iron(III) complexes with 5-iodouracil and 5-iodouracil-histidine and their antitumour activity

Complexes of the type [Al(HL)(OH)Cl(2)], [M(HL)(OH)(2)Cl] and [M'(HL)(L')(OH)Cl], where HL = 5-iodouracil; HL' = histidine; M = Cr(III), Fe(III) and M' = Al(III), Cr(III), Fe(III), were synthesized and characterized. The complexes are polymeric showing high decomposition points and are insoluble in water and common organic solvents. The mu(eff) values, electronic spectral bands and ESR spectra suggest a polymeric 6-coordinate spin-free octahedral stereochemistry for the Cr(III) and Fe(III) complexes. 5-Iodouracil acts as a monodentate ligand coordinating to the metal ion through the O atom of C((4)) = O while histidine through the O atom of -COO(- ) and the N atom of -NH(2) group. In vivo antitumour effect of 5-iodouracil and its complexes was examined on C(3)H /He mice against P815 murine mastocytoma. As evident from their T/C values, Cr(III) and Fe(III) complexes display significant and higher antitumour activity compared to the 5-iodouracil ligand. The in vitro results of the complexes on the same cells indicate that Cr(III) and Fe(III) complexes show higher inhibition on (3)H-thymidine and (3)H-uridine incorporation in DNA and RNA replication, respectively, at a dose of 5 microg/mL.     

Protein analysis with terbium (III) and sodium dodecyl sulphonate by a second-order scattering technique.

This is the first report of terbium(III) as a probe of second-order scattering (SOS) for the determination of proteins in human serum at nanogram levels. A sensitive method has been developed using light scattering, based on the fact that the weak SOS of proteins can be enhanced in the presence of terbium(III) and sodium dodecyl sulphonate (SDS). With this method, 7.0 x 10(-9)-1.0 x 10(-5) g/mL human serum albumin (HSA) and 5.0 x 10(-9)-5.0 x 10(-6) g/mL gamma-globulin can be determined; the detection limits were 4.4 ng/mL for HSA and 3.1 ng/mL for gamma-globulin. The method has been applied to the detection of total proteins in human serum samples, and the results are consistent with those obtained by the Coomassie brilliant blue (CBB) G-250 assay.     

Interaction of proteins with aluminum(III)–chlorophosphonazo III by resonance Rayleigh scattering method

In weak acid medium, aluminum(III) can react with chlorophosphonazo III [CPA(III), H₈L] to form a 1:1 coordination anion [Al(OH)(H₄L)]^2‐. At the same time, proteins such as bovine serum albumin (BSA), lysozyme (Lyso) and human serum albumin (HSA) existed as large cations with positive charges, which further combined with [Al(OH)(H₄L)]^2‐ to form a 1:4 chelate. This resulted in significant enhancement of resonance Rayleigh scattering (RRS), second‐order scattering (SOS) and frequency doubling scattering (FDS). In this study, we investigated the interaction between [Al(OH)(H₄L)]^2‐ and proteins, optimization of the reaction conditions and the spectral characteristics of RRS, SOS and FDS. The maximum RRS wavelengths of different protein systems were located at 357–370 nm. The maximum SOS and FDS wavelengths were located at 546 and 389 nm, respectively. The scattering intensities (ΔI) of the three methods were proportional to the concentration of the proteins, within certain ranges, and the detection limits of the most sensitive RRS method were 2.6–9.3 ng/mL. Moreover, the chelate reaction mechanism or the reasons for the enhancement of RRS were discussed through absorption spectra, fluorescence spectra and circular dichroism (CD) spectra. Copyright © 2013 John Wiley & Sons, Ltd.     

Limiting factors for microbial Fe(III) -reduction in a landfill leachate polluted aquifer (Vejen, Denmark)

Abstract Aquifer sediment samples from two locations within the anaerobic leachate plume of a municipal landfill were compared with respect to microbiology (especially Fe(III)-reduction) and geochemistry. The samples close to the landfill were characterized by low contents of Fe(III), whereas samples from the more distant cluster were rich in Fe(III)-oxides. The active microbial population seemed to be less dense in samples more distant from the landfill (measured by ATP and phospholipid fatty acids (PLFA)), but the microbial communities were very similar in the two sample clusters according to the composition of PLFA. Very little, if any, Fe(III)-reduction was observed close to the landfill, but all the more distant samples showed evident microbially mediated Fe(III)-reduction. After amendment with both acetate and Fe(III), all the samples showed a potential for Fe(III)-reduction, and the in situ Fe(III)-reduction seemed to be limited by the lack of Fe(III)-availability. It was suggested, that Fe(III)-reducing populations might be facultative, surviving by use of other electron-acceptors than Fe(III), when Fe(III) is not available for reduction.     

Towards a new attenuating compound: a potentiometric, spectrophotometric and NMR equilibrium study on Fe(III), Al(III) and a new tetradentate mixed bisphosphonate-hydroxypyridinonate ligand

Coordination properties toward Fe(III) and Al(III) of a mixed bisphosphonate-hydroxypyridinonate ligand are presented. Potentiometric, spectrophotometric and NMR results allowed to conclude that Fe(III) and Al(III) coordination takes place on the pyridinone moiety. The high steric hindrance prevents the possibility of simultaneous coordination of both groups to the same metal ion. Quantum mechanical calculations confirm this finding allowing to determine the minimal length of the linker necessary for a stable conformation of complexes in which Fe(III) is coordinated both by pyridinone and bisphosphonate groups.     

海洋沉积物中铁还原细菌组成及异化铁还原与产氢性质分析

【背景】一些铁还原细菌具有异化铁还原与产氢的能力,该类细菌在环境污染修复的同时能够解决能源问题。【目的】从海洋沉积物中富集获得异化铁还原菌群,明确混合菌群组成、异化铁还原及产氢性质。获得海洋沉积物中异化铁还原混合菌群组成,分析菌群异化铁还原和产氢性质。【方法】利用高通量测序技术分析异化铁还原菌群的优势菌组成,在此基础上,分析异化铁还原混合菌群在不同电子供体培养条件下异化铁还原能力和产氢性质。【结果】高通量数据表明,在不溶性氢氧化铁为电子受体和葡萄糖为电子供体厌氧培养条件下,混合菌群的优势菌属主要是梭菌(Clostridium),属于发酵型异化铁还原细菌。混合菌群能够利用电子供体蔗糖、葡萄糖以及丙酮酸钠进行异化铁还原及发酵产氢。葡萄糖为电子供体时,菌群累积产生Fe(Ⅱ)浓度和产氢量最高,分别是59.34±6.73 mg/L和629.70±11.42 mL/L。【结论】异化铁还原混合菌群同时具有异化铁还原和产氢能力,拓宽了发酵型异化铁还原细菌的种质资源,探索异化铁还原细菌在生物能源方面的应用。     

Influence of Biogenic Fe(II) on Bacterial Crystalline Fe(III) Oxide Reduction

Bacterial crystalline Fe(III) oxide reduction has the potential to significantly influence the biogeochemistry of anaerobic sedimentary environments where crystalline Fe(III) oxides are abundant relative to poorly crystalline (amorphous) phases. A review of published data on solid-phase Fe(III) abundance and speciation indicates that crystalline Fe(III) oxides are frequently 2- to S 10-fold more abundant than amorphous Fe(III) oxides in shallow subsurface sediments not yet subjected to microbial Fe(III) oxide reduction activity. Incubation experiments with coastal plain aquifer sediments demonstrated that crystalline Fe(III) oxide reduction can contribute substantially to Fe(II) production in the presence of added electron donors and nutrients. Controls on crystalline Fe(III) oxide reduction are therefore an important consideration in relation to the biogeochemical impacts of bacterial Fe(III) oxide reduction in subsurface environments. In this paper, the influence of biogenic Fe(II) on bacterial reduction of crystalline Fe(III) oxides is reviewed and analyzed in light of new experiments conducted with the acetate-oxidizing, Fe(III)-reducing bacterium (FeRB) Geobacter metallireducens . Previous experiments with Shewanella algae strain BrY indicated that adsorption and/or surface precipitation of Fe(II) on Fe(III) oxide and FeRB cell surfaces is primarily responsible for cessation of goethite ( f -FeOOH) reduction activity after only a relatively small fraction (generally < 10%) of the oxide is reduced. Similar conclusions are drawn from analogous studies with G. metallireducens . Although accumulation of aqueous Fe(II) has the potential to impose thermodynamic constraints on the extent of crystalline Fe(III) oxide reduction, our data on bacterial goethite reduction suggest that this phenomenon cannot universally explain the low microbial reducibility of this mineral. Experiments examining the influence of exogenous Fe(II) (20 mM FeCl 2 ) on soluble Fe(III)-citrate reduction by G. metallireducens and S. algae showed that high concentrations of Fe(II) did not inhibit Fe(III)-citrate reduction by freshly grown cells, which indicates that surface-bound Fe(II) does not inhibit Fe(III) reduction through a classical end-product enzyme inhibition mechanism. However, prolonged exposure of G. metallireducens and S. algae cells to high concentrations of soluble Fe(II) did cause inhibition of soluble Fe(III) reduction. These findings, together with recent documentation of the formation of Fe(II) surface precipitates on FeRB in Fe(III)-citrate medium, provide further evidence for the impact of Fe(II) sorption by FeRB on enzymatic Fe(III) reduction. Two different, but not mutually exclusive, mechanisms whereby accumulation of Fe(II) coatings on Fe(III) oxide and FeRB surfaces may lead to inhibition of enzymatic Fe(III) oxide reduction activity (in the absence of soluble electron shuttles and/or Fe(III) chelators) are identified and discussed in relation to recent experimental work and theoretical considerations.     

A simple and sensitive resonance Rayleigh scattering method for determination of As(III) using aptamer‐modified nanogold as a probe

A simple and selective aptamer (ssDNA)‐modified nanogold probe (AussDNA) was prepared for the determination of trace As(III) in HEPES buffer solution (pH 8.2) containing 0.05 mol/L NaCl. The method coupled the aptamer reaction of AussDNA–As(III) and the resonance Rayleigh scattering (RRS) of nanogold aggregations at 278 nm. When the As(III) concentration increased, the RRS intensity at 278 nm increased to form more nanogold aggregation and a stable As(III)–ssDNA complex. Under selected conditions, the increased RRS intensity (ΔI) was linear to the concentration of As(III) in the range 3.8–230.4 ng/mL, with a detection limit of 1.9 ng/mL. This RRS method was applied to detect As(III) in water samples, with simplicity, sensitivity and selectivity. Copyright © 2013 John Wiley & Sons, Ltd.     

A sensitive method for determination of trace amounts of chromate (III) with terbium (III) sodium hexametaphosphate chelate as fluorescent probe

Based on the fluorescence quenching of Terbium (III)‐sodium hexametaphosphate (Tb/SHMP) chelates in the presence chromate (III), a sensitive fluorimetric method was developed for the determination of trace amounts of chromium (III) in aqueous solutions. Under the optimum conditions, the linear calibration graph was obtained (R = 0.996). The linear range and detection limit of Cr (III) were 7.69 × 10^?7 to 1.15 × 10^?4 mol L^?1 and 4.50 × 10^?7 mol L^?1, respectively. The proposed method had a wider linear range and was proved to be very sensitive, rapid and simple. The method was applied successfully to the determination of chromium (III) in the synthetic samples and real water samples. Moreover, the reaction mechanism was discussed through the fluorescence lifetime and proved to be dynamic quenching behavior. Copyright © 2010 John Wiley & Sons, Ltd.     

Binding study of lysozyme with Al(III) using chemiluminescence analysis

The binding behavior of lysozyme with Al(III) is described using luminol as a luminescence probe by flow injection–chemiluminescence (FI–CL) analysis. It was found that the CL intensity of the luminol–lysozyme reaction could be markedly enhanced by Al(III), and the increase in CL intensity was linear with the Al(III) concentration over the range 0.3–30.0 pg mL^?1, with a detection limit of 0.1 pg mL^?1 (3σ). Based on the interaction model of lysozyme with Al(III), lg[(I ? I₀)/(2I₀ ? I)] = lgK + nlg[M], the binding constant K = 6.84 × 10⁶ L mol^–1 and the number of binding sites (n) = 0.76. The relative standard deviations were 3.2, 2.4 and 2.0% for 10.0, 20.0 and 30.0 pg mL^?1 Al(III) (n = 7), respectively. This new method was successfully applied to continuous, quantitative monitoring of picogram level Al(III) in human saliva following oral intake of compound aluminum hydroxide tablets. It was found that Al(III) in saliva reached a maximum of 101.2 ng mL^?1 at 3.0 h. The absorption rate constant k_a, elimination rate constant k and half‐life time t_1/2 of Al(III) were 1.378 h^?1, 0.264 h^?1 and 2.624 h, respectively. Copyright © 2013 John Wiley & Sons, Ltd.     

Highly sensitive spectrofluorimetric determination of trace amounts of prulifloxacin using the aluminium(III)–prulifloxacin system

The fluorescence of the prulifloxacin (PUFX)–Al(III) system was investigated . Experiments indicated that the fluorescence intensity of prulifloxacin could be greatly enhanced by Al(III) and sensitized by sodium dodecylbenzene sulphonate (SDBS). Accordingly, a sensitive spectrofluorimetric method for the determination of prulifloxacin was established. While excited at 275 nm, the enhanced fluorescence intensity at 412 nm of the system (ΔF) showed a good linear relationship with the concentration of prulifloxacin within the range 4.0 × 10^–8–3.0 × 10^–6 mol/L. The regression equation was ΔF = 9.83 + 10.8 × 10⁷c (mol/L); the correlation coefficient and detection limit (3σ/k) were 0.99901 and 2.0 × 10^–8 mol/L, respectively. The proposed method has been successfully applied to determine prulifloxacin in real pharmaceutical samples. The luminescence mechanism of the system is also discussed in detail. Copyright © 2008 John Wiley & Sons, Ltd.     

Fe(III) complexes of d-glucose and d-fructose

Fe(III)-saccharide complexes of d-glucose and d-fructose have been synthesized from methanol using stoichiometric quantities of sodium salts of the corresponding saccharides. Both the compounds were isolated in the solid state and characterized by various analytical, spectroscopic, magnetic and cyclic voltammetric methods. Both the complexes were found to be stable, in solution, in the pH range 2.5–12.0.This paper is dedicated to Professor Richard H. Holm on his 60th birthday.     

Determination of sulpiride in pharmaceutical preparations and biological fluids using a Cr (III) enhanced chemiluminescence method

A highly sensitive and simple method for identifying sulpiride in pharmaceutical formulations and biological fluids is presented. The method is based on increased chemiluminescence (CL) intensity of a luminol–H₂O₂ system in response to the addition of Cr (III) under alkaline conditions. The CL intensity of the luminol–H₂O₂–Cr (III) system was greatly enhanced by the addition of sulpiride and the CL intensity was proportional to the concentration of sulpiride in a sample solution. Various parameters affecting the CL intensity were systematically investigated and optimized for determination of the sulpiride in a sample. Under the optimum conditions, the CL intensity was proportional to the concentration of sulpiride in the range of 0.068–4.0 µg/mL, with a good correlation coefficient of 0.997. The limit of detection (LOD) and limit of quantification (LOQ) were found to be 8.50 × 10^‐6 µg/mL and 2.83 × 10^‐5 µg/mL, respectively. The method presented here produced good reproducibility with a relative standard deviation (RSD) of 2.70% (n = 7). The effects of common excipients and metal ions were studied for their interference effect. The method was validated statistically through recovery studies and successfully applied for the determination of sulpiride in pure form, pharmaceutical preparations and spiked human plasma samples. The percentage recoveries were found to range from 99.10 to 100.05% for pure form, 98.12 to 100.18% for pharmaceutical preparations and 97.9 to 101.4% for spiked human plasma. Copyright © 2012 John Wiley & Sons, Ltd.     

Geovibrio ferrireducens,a phylogenetically distinct dissimilatory Fe(III)-reducing bacterium

A new, phylogenetically distinct, dissimilatory, Fe(III)-reducing bacterium was isolated from surface sediment of a hydrocarbon-contaminated ditch. The isolate, designated strain PAL-1, was an obligately anaerobic, non-fermentative, motile, gram-negative vibrio. PAL-1 grew in a defined medium with acetate as electron donor and ferric pyrophosphate, ferric oxyhydroxide, ferric citrate, Co(III)-EDTA, or elemental sulfur as sole electron acceptor. PAL-1 also used proline, hydrogen, lactate, propionate, succinate, fumarate, pyruvate, or yeast extract as electron donors for Fe(III) reduction. It is the first bacterium known to couple the oxidation of an amino acid to Fe(III) reduction. PAl-1 did not reduce oxygen, Mn(IV), U(VI), Cr(VI), nitrate, sulfate, sulfite, or thiosulfate with acetate as the electron donor. Cell suspensions of PAL-1 exhibited dithionite-reduced minus air-oxidized difference spectra that were characteristic of c-type cytochromes. Analysis of the 16S rRNA gene sequence of PAL-1 showed that the strain is not related to any of the described metal-reducing bacteria in the Proteobacteria and, together with Flexistipes sinusarabici, forms a separate line of descent within the Bacteria. Phenotypically and phylogenetically, strain PAl-1 differs from all other described bacteria, and represents the type strain of a new genus and species, Geovibrio ferrireducens. Received: 26 September 1995 / Accepted: 28 February 1996     

Adhesion of Dissimilatory Fe(III)-Reducing Bacteria to Fe(III) Minerals

The metabolism of dissimilatory iron-reducing bacteria (DIRB) may provide a means of remediating contaminated subsurface soils. The factors controlling the rate and extent of bacterial F(III) mineral reduction are poorly understood. Recent research suggests that molecular-scale interactions between DIRB cells and Fe(III) mineral particles play an important role in this process. One of these interactions, cell adhesion to Fe(III) mineral particles, appears to be a complex process that is, at least in part, mediated by a variety of surface proteins. This study examined the hypothesis that the flagellum serves as an adhesin to different Fe(III) minerals that range in their surface area and degree of crystallinity. Deflagellated cells of the DIRB Shewanella algae BrY showed a reduced ability to adhere to hydrous ferric oxide (HFO) relative to flagellated cells. Flagellated cells were also more hydrophobic than deflagellated cells. This was significant because hydrophobic interactions have been previously shown to dominate S. algae cell adhesion to Fe(III) minerals. Pre-incubating HFO, goethite, or hematite with purified flagella inhibited the adhesion of S. algae BrY cells to these minerals. Transposon mutagenesis was used to generate a flagellum-deficient mutant designated S. algae strain NF. There was a significant difference in the rate and extent of S. algae NF adhesion to HFO, goethite, and hematite relative to that of S. algae BrY. Amiloride, a specific inhibitor of Na + -driven flagellar motors, inhibited S. algae BrY motility but did not affect the adhesion of S. algae BrY to HFO. S.algae NF reduced HFO at the same rate as S. algae BrY. Collectively, the results of this study support the hypothesis that the flagellum of S. algae functions as a specific Fe(III) mineral adhesin. However, these results suggest that flagellum-mediated adhesion is not requisite for Fe(III) mineral reduction.     

Biomineralization of Poorly Crystalline Fe(III) Oxides by Dissimilatory Metal Reducing Bacteria (DMRB)

Dissimilatory metal reducing bacteria (DMRB) catalyze the reduction of Fe(III) to Fe(II) in anoxic soils, sediments, and groundwater. Two-line ferrihydrite is a bioavailable Fe(III) oxide form that is exploited by DMRB as a terminal electron acceptor. A wide variety of biomineralization products result from the interaction of DMRB with 2-line ferrihydrite. Here we describe the state of knowledge on the biotransformation of synthetic 2-line ferrihydrite by laboratory cultures of DMRB using select published data and new experimental results. A facultative DMRB is emphasized ( Shewanella putrefaciens ) upon which most of this work has been performed. Key factors controlling the identity of the secondary mineral suite are evaluated including medium composition, electron donor and acceptor concentrations, ferrihydrite aging/recrystallization status, sorbed ions, and co-associated crystalline Fe(III) oxides. It is shown that crystalline ferric (goethite, hematite, lepidocrocite), ferrous (siderite, vivianite), and mixed valence (magnetite, green rust) iron solids are formed in anoxic, circumneutral DMRB incubations. Some products are well rationalized based on thermodynamic considerations, but others appear to result from kinetic pathways driven by ions that inhibit interfacial electron transfer or the precipitation of select phases. The primary factor controlling the nature of the secondary mineral suite appears to be the Fe(II) supply rate and magnitude, and its surface reaction with the residual oxide and other sorbed ions. The common observation of end-product mineral mixtures that are not at global equilibrium indicates that microenvironments surrounding respiring DMRB cells or the reaction-path trajectory (over Eh-pH space) may influence the identity of the final biomineralization suite.     

Online column preconcentration for speciation and selective determination of Cr(III) in natural water samples using flow injection with chemiluminescence detection

A simple, rapid, sensitive and inexpensive approach is described in this work based on a combination of solid-phase extraction of 8-hydroxyquinoline (8HQ), for speciation and preconcentration of Cr(III) and Cr(VI) in river water, and the direct determination of these species using a flow injection system with chemiluminescence detection (FI–CL) and a 4-diethylamino phenyl hydrazine (DEAPH)–hydrogen peroxide system. At different pH, the two forms of chromium [Cr(III) and Cr(VI)] have different exchange capacities for 8HQ, therefore two columns were constructed; the pH of column 1 was adjusted to pH 3 for retaining Cr(III) and column 2 was adjusted to pH 1 for retaining of Cr(VI). The sorbed Cr(III) and Cr(VI) species were eluted from columns using 3.0 ml of 0.1 N of HCl and 3.0 ml of 0.1 N of NaOH, respectively. The flow injection–chemiluminescence (FI–CL) method is based on light emitted due to the oxidation of DEAPH by the H₂O₂ in the presence of Cr(III), which catalyzes the reaction. The flow cell is a transparent coiled tube made from glass (2.0 × 4.0, inner and outer diameter) and located close to the photodetector. The flow parameters: flow rate, sample volume, flow cell length, and distance to the CL detector were studied and optimized. Under optimum flow conditions, the Cr(III) concentration can be determined over the range 5–350 μg L⁻¹ with a limit of detection of 1.2 μg L⁻¹, as the Cr(III) concentration is proportional to the intensity of the CL signal. The relative standard deviations (%) for 10 and 50 μg L⁻¹ Cr(III) were 1.2% and 3.2%, respectively. The effects of Al(III), Cd(II), Zn(II), Hg(II), Pb(II), Co(II), Cu(II), Ni(II), Mn(II), Ca(II), and Fe(III) were investigated. The proposed method is highly selective and sensitive, enabling a rapid determination of the Cr(III) amount in the presence of other interfering metals. Finally, the FI–CL method was examined in five river water samples with excellent recoveries.     

Complexation study of europium(III) and curium(III) with urea in aqueous solution investigated by time-resolved laser-induced fluorescence spectroscopy

The complex formation of europium(III) and curium(III) with urea in aqueous solution has been studied at I = 0.1 M (NaClO₄), room temperature and trace metal concentrations in the pH-range of 1-8 at various ligand concentrations using time-resolved laser-fluorescence spectroscopy. While for curium(III) the luminescence maximum is red shifted upon complexation, in case of europium(III) emission wavelengths remain unaltered but a significant change in peak splitting occurs. Both heavy metals form weak complexes of the formulae ML³⁺ and MLOH²⁺ with urea. Stability constants were determined to be log β₁₁₀ = −0.12 ± 0.05 and log β_11-1 = −6.86 ± 0.15 for europium(III) and log β₁₁₀ = −0.28 ± 0.12 and log β_11-1 = −7.01 ± 0.15 for curium(III).