Amberlite IR-120 Modified with 8-Hydroxyquinoline as Efficient Adsorbent for Solid-Phase Extraction and Flame Atomic Absorption Determination of Trace Amounts of Some Metal Ions

In this study, a solid-phase extraction method combined with atomic absorption spectrometry for extraction, preconcentration, and determination of iron (Fe³⁺), copper (Cu²⁺), and lead (Pb²⁺) ions at trace levels in water samples has been reported. The influences of effective parameters such as flow rate, pH, eluent conditions (type, volume, and concentration), sample volumes, and interference of matrix ions on metal ions recoveries were studied. Under optimized conditions, the limits of detection were found in the range of 0.7–2.2 μg L⁻¹, while preconcentration factors for Fe³⁺, Cu²⁺, and Pb²⁺ ions were found to be 166, 200, and 250, respectively, and loading half time (t _1/2) values were less than 2 min for all analyte ions. The proposed procedure was applied for the determination of metal ions in different water samples with recovery of >94.4% and relative standard deviation less than 4.4% for N = 5.     

Room Temperature Ionic Liquid-Based Dispersive Liquid Phase Microextraction for the Separation/Preconcentration of Trace Cd2+ as 1-(2-pyridylazo)-2-naphthol (PAN) Complex from Environmental and Biological Samples and Determined by FAAS

The current work develops a new green methodology for the separation/preconcentration of cadmium ions (Cd²⁺) using room temperature ionic liquid-dispersive liquid phase microextraction (RTIL–DLME) prior to analysis by flame atomic absorption spectrometry with microsample introduction system. Room temperature ionic liquids (RTIL) are considered “Green Solvents” for their thermally stable and non-volatile properties, here 1-butyl-3-methylimidazolium hexafluorophosphate [C₄mim][PF₆] was used as an extractant. The preconcentration of Cd²⁺ in different waters and acid digested scalp hair samples were complexed with 1-(2-pyridylazo)-2-naphthol and extracted into the fine drops of RTILs. Some significant factors influencing the extraction efficiency of Cd²⁺ and its subsequent determination, including pH, amount of ligand, volume of RTIL, dispersant solvent, sample volume, temperature, and incubation time were investigated in detail. The limit of detection and the enhancement factor under the optimal conditions were 0.05 μg/L and 50, respectively. The relative standard deviation of 100 μg/L Cd²⁺ was 4.3 %. The validity of the proposed method was checked by determining Cd²⁺ in certified reference material (TM-25.3 fortified water). The sufficient recovery (>98 %) of Cd²⁺ with the certified value. The mean concentrations of Cd in lake water 13.2, waste water 15.7 and hair sample 16.8 μg/L, respectively and the developed method was applied satisfactorily to the preconcentration and determination of Cd²⁺ in real samples.     

Modification of Gold Nanoparticle Loaded on Activated Carbon with Bis(4-methoxysalicylaldehyde)-1,2-Phenylenediamine as New Sorbent for Enrichment of Some Metal Ions

In this study, a new sorbent based on the gold nanoparticle loaded in activated carbon (Au-NP-AC) was synthesized and modified by bis(4-methoxy salicylaldehyde)-1,2-phenylenediamine (BMSAPD). This sorbent, which is abbreviated as Au-NP-AC-BMSAPD, has been applied for the enrichment and preconcentration of trace amounts of Co²⁺, Cu²⁺, Ni²⁺, Fe²⁺, Pb²⁺, and Zn²⁺ ions in real samples. All metal ions under study were retained on the Au-NP-AC-BMSAPD sorbent by complexation of the ions with the BMSAPD ligand, providing an efficient preconcentration fashion. The retained metal ions were then eluted from the sorbent by HNO₃ and detected by flame atomic absorption spectrometry. The analytical parameters including pH, amount of ligand, and the nature of the eluent and solid phase were evaluated to obtain the optimum condition for the preconcentration factor. Following the optimum conditions, a preconcentration factor of 200 was obtained for all the metal ions under study with detection limits of 1.4–2.6 ng mL⁻¹. The method has been successfully applied for the extraction and determination of the ion content in the same real samples with recoveries in the range of 95–99.6% and a relative standard deviation lower than 4.0%.     

Application of Poly 1,8‐diaminonaphthalene/multiwalled carbon nanotubes‐COOH hybrid material as an efficient sorbent for trace determination of cadmium and lead ions in water samples

Poly 1,8‐diaminonaphthalene/multiwalled carbon nanotubes‐COOH hybrid material as an effective sorbents in solid phase extraction has been developed for the separation and preconcentration of Cd(II) and Pb(II) at trace levels in environmental water samples. The results indicate that the novel nanocomposite show a high affinity for these heavy metals due to the presence of several good extractive sites, which are introduced to the synthesized nanocomposite The maximum adsorption capacity of the synthesized sorbent for cadmium and lead ions was found to be 101.2 and 175.2 mg g^?1, respectively. The detection limits of this method were 0.09 and 0.7 ng ml^?1 for Cd(II) and Pb(II), respectively. Copyright © 2014 John Wiley & Sons, Ltd.     

Immobilization of <Emphasis Type="Italic">Pseudomonas putida</Emphasis> PT in resistant matrices to environmental stresses: a strategy for continuous removal of heavy metals under extreme conditions

The purpose of this study was to investigate the potential of immobilized lead- and cadmium-resistant Pseudomonas putida strain PT to remove heavy metals from aqueous medium under extreme conditions. The tolerance and accumulation of cadmium and lead ions by strain PT were investigated by minimal inhibitory concentration (MIC) determination and polymerase chain reaction (PCR) of cadA gene, respectively. The surface chemical functional groups of P. putida PT involved in the metal biosorption were identified by Fourier transform infrared (FTIR). Pseudomonas putida PT was immobilized in three matrices include carboxy-methyl cellulose (CMC), rice bran, and a new composite made of alginate, polyvinyl alcohol (PVA), and CaCO₃ to prepare heavy metal adsorbent. The biosorbents were analyzed by SEM, and their metal removal capability was assayed in two consecutive cycles by atomic absorption spectroscopy. The viability of immobilized bacterial cells was determined by flow cytometry during storage at 4 °C and exposure to the environmental stresses (pH and temperature). The results showed that PT strain was resistant up to 10 mM Pb²⁺ and 8 mM Cd²⁺. FTIR analysis revealed that alcohol, sulfur, phosphate, esters, and amide groups played important roles in metal biosorption process and, also change in metabolic reactions like hydration and polyesters accumulation was observed after metal biosorption. The presence of cadA gene, a heavy metal translocating pump-coding gene, indicated the ability of metals bioaccumulation by the PT strain. Immobilized cells in alginate–PVA–CaCO₃ and rice bran showed the highest metal removal efficiency for Pb²⁺ as 75% and Cd²⁺ as 96.7%, respectively. Metal adsorbents were reusable, and the highest removal efficiency in the second cycle was observed in inoculated alginate–PVA–CaCO₃ (79.5% Pb²⁺ and 45% Cd²⁺). Flow cytometric analysis represented that the immobilized cell viability was retained (<?97%) after 4 weeks storage at 4 °C. Viability under two environmental stresses in all matrices was as follows: <?96% at 25 °C, <?87% at 45 °C, <?85% at pH 4,?<?96% at pH 7, and?<?89% at pH 11. The results signify that these metal adsorbents are efficient technological tools for bioremediation even in harsh environmental conditions.     

A simple method to prepare poly(amic acid)-modified biomass for enhancement of lead and cadmium adsorption

A modified biomass of baker's yeast was prepared by grafting poly(amic acid), which was obtained via reaction of pyromellitic dianhydride (PMDA) and thiourea, onto the biomass surface at 50 °C for 4 h. This method was simpler than other reported chemical grafting methods. The presence of poly(amic acid) on the biomass surface was verified by FTIR, X-ray photoelectron spectroscopy (XPS) and microscope analyses, and the amount of carboxylate and amide groups in the biomass surface were found to be 1.36 and 0.7 mmol g⁻¹ through potentiometric titration. Compared with the pristine biomass, the adsorption capacity of the modified biomass increased 15- and 11-fold for Cd²⁺ and Pb²⁺, respectively. According to the Langmuir equation, the maximum uptake capacities (q_m) for lead and cadmium were 210.5 and 95.2 mg g⁻¹, respectively. The kinetics for cadmium and lead adsorption followed the pseudo-second-order kinetics. FTIR and XPS demonstrated that carboxyl, amide, and hydroxyl groups were involved in the adsorption of lead and cadmium, and the adsorption mechanism for the two metal ions included ion exchange, electrostatic interaction and complexation.     

The Use of Fungal Biomass Agaricus bisporus Immobilized on Amberlite XAD-4 Resin for the Solid-Phase Preconcentration of Thorium

Solid-phase extraction method was developed for the preconcentration of thorium (Th). Fungal biomass Agaricus bisporus was immobilized to Amberlite XAD-4 as solid-phase sorbent. The critical parameters such as pH of the sample solution, flow rate of the sample, volume of the sample, and the effect of major ions that affect the preconcentration of thorium in this system were evaluated. The optimum pH for the sorption of Th is 6.0, and quantitative elution occurs with 1.0 mol L^?1HCl. The loading capacity was determined as 0.079 mmol g^?1. The optimized method was validated through analysis of the certified reference material of tea leaves (NCS ZC73014) and successfully applied to the determination of Th in a real ore sample with satisfactory results.     

Silver Nanoparticles as a New Solid-Phase Adsorbent and Its Application to Preconcentration and Determination of Lead from Biological Samples

A new, simple, and fast method for preconcentration and determination of trace amount of lead from biological samples was developed by modified silver nanoparticle-based solid-phase extraction technique and graphite furnace atomic absorption spectrometry. In this study, morin was used as a complexing agent. Some factors influencing the recovery of lead including pH, sample flow rate, type, flow rate, and least amount of the eluent for elution of the lead from silver nanoparticles were studied and optimized. Under the optimum conditions, the detection limit of this method was 68 ng L⁻¹, and the relative standard deviation was 4.1% (n = 10, c = 20 μg L⁻¹). The developed procedure was validated by the analysis of certified reference material and applied to the recovery and determination of lead in biological samples.     

Resting Eggs as New Biosorbent for Preconcentration of Trace Elements in Various Samples Prior to Their Determination by FAAS

In this study, the resting eggs of aquatic creatures living in freshwater (Daphnia, Cladocera, Crustacean) ecosystems were used as a novel biosorbent extractant for synchronous preconcentration of trace Cd(II), Co(II), Cu(II), Mn(II), and Ni(II) previous to measurement by flame atomic absorpiton spectrometry (FAAS). Using column procedures, optimization studies were conducted to realize the effective adsorption of the analyte ions such as the solution pH, amount of the biosorbent, volume of the sample, interfering ions, etc. A high preconcentration factor of 67 and low relative standard deflection of ≤4.1 % (n?=?8) were obtained. The invention constrains based on the 3 s/b criterion were 2.4 for Cd(II), 41.4 for Co(II), 4.2 for Cu(II), 3.0 for Mn(II), and 9.6 μg L^?1 for Ni(II). The accuracy of the method was verified by analysis of a certified standard reference material. The used procedure was applied to the definition of the analytes in diverse environmental samples with convincing results. Consequently, the resting eggs of Daphnia can be used as a biosorbent for preconcentration and biosorption studies.     

Effect of heavy metals (Cu,Cd and Pb) on aspartate and alanine aminotransferase in Ruditapes philippinarum (Mollusca: Bivalvia)

The accumulation of cadmium, copper and lead and their effects on aspartate and alanine aminotransferases in digestive gland, gills, foot and soft body in the clam Ruditapes philippinarum were examined. The animals were exposed to different concentrations: Cd (200–600 μg·l⁻¹), Pb (350–700 μg·l⁻¹) and Cu (10–20 μg·l⁻¹) for 7 days. The highest concentrations were found in digestive gland for cadmium and copper, and in gills for lead, and the lowest values were observed in the foot. Aspartate aminotransferase activity (AST), in general, was not inhibited by cadmium, lead or copper during the exposure. Only in clams exposed to cadmium (600 μg·l⁻¹, 7 days) and copper (20 μg·l⁻¹, 5 days) were observed significant differences (P<0.05) in foot and gills, respectively, with respect to control. In the case of alanine aminotransferase activity (ALT), significant differences were observed for cadmium and lead in treated animals with respect to control. With regard to copper, a decrease in ALT was observed in gills and foot exposed to 20 μg·l⁻¹. A significant correlation (P<0.05) was observed between ALT and metal accumulation for cadmium, copper and lead in gills. In the case of soft body, only cadmium and lead showed a significant correlation. In summary, R. philippinarum can be considered a bioindicator species for cadmium and lead accumulation and ALT could be useful as biomarker of sublethal stress for these metals in soft tissues and gills. Only gills can be considered an adequate target tissue for copper.     

Inhibitory effects of cadmium on carbonic anhydrase activity and ionic regulation of the estuarine crab Chasmagnathus granulata (Decapoda,Grapsidae)

This work was aimed at evaluating the gill carbonic anhydrase (CA) activity of the estuarine crab Chasmagnathus granulata exposed in vivo to cadmium, at different salinities. The in vivo effect of the specific inhibitor acetazolamide (AZ) was also assayed. Besides, the inhibition of CA activity by different heavy metals (cadmium, copper, zinc) and AZ were evaluated under in vitro conditions. For the in vivo assays, adult males were acclimated to salinities of 2.5 or 30‰. The corresponding 96-h LC₅₀ of cadmium was 2.69 mg l⁻¹ at 2.5‰, and >50 mg l⁻¹ at 30‰. Cadmium only caused a significant lower CA activity than control at 2.5‰. EC₅₀ for CA inhibition was estimated to be 1.59 mg l⁻¹ at 2.5‰. Statistical differences in Na⁺ hemolymphatic levels (P<0.05) were only detected at 2.5‰, between 0 and 1.25 mg l⁻¹ of cadmium, but no statistical differences were observed for Cl⁻ levels at any assayed salinity. As CA inhibition registered at 2.5‰ was followed by only changes in Na⁺ concentration, it is likely that cadmium exposure could differentially affect ions permeability, among others factors. The concentrations that inhibited in vitro 50% of enzymatic activity (IC₅₀) were 2.15×10⁻⁵, 1.62×10⁻⁵, 3.75×10⁻⁶ and 4.4×10⁻¹⁰ M for cadmium, copper, zinc and AZ, respectively. The comparison with IC₅₀ values of other aquatic species, indicates a higher CA sensitivity for C. granulata to pollutants.     

Crystal structure and thermal characterization of cadmium oxalate [CdC2O4 · 3H2O] and barium-doped cadmium oxalate [Ba0.5Cd0.5(C2O4)2 · 5H2O] single crystals grown in silica gel

Pure cadmium oxalate trihydrate (COT) and barium added cadmium oxalate (BCO) single crystals were grown by controlled diffusion of Cd²⁺ and Ba²⁺ ions in silica gel at ambient temperature. A single test tube technique coupled with gel aging conferred maximum size crystals by controlling the nucleation rate. It was found that the pH and age of the gel greatly influenced the crystal quality, their size and transparency. Grown crystals CdC₂O₄ · 3H₂O and Ba_0.5Cd_0.5(C₂O₄)₂ · 5H₂O were characterized by X-ray diffraction, Fourier transform infrared spectroscopy and thermal analysis. Effect of barium dopant on the growth and morphology of cadmium oxalate was studied. Pure cadmium oxalate crystallized in triclinic system and the barium-doped cadmium oxalate crystallized in hexagonal system with massive changes in their unit cell parameters. The infrared spectrum revealed the presence of oxalate ligands and water of hydration in both the pure and barium-doped crystals. Thermal analysis showed that the grown crystals were dehydrated thermally even from lower temperatures and the doped crystals were found more stable.     

Hyperaccumulator Oilcake Manure as an Alternative for Chelate-Induced Phytoremediation of Heavy Metals Contaminated Alluvial Soils

The ability of hyperaccumulator oilcake manure as compared to chelates was investigated by growing Calendula officinalis L for phytoremediation of cadmium and lead contaminated alluvial soil. The combinatorial treatment T₆ [2.5 g kg^?1oilcake manure + 5 mmol kg^?1 EDDS] caused maximum cadmium accumulation in root, shoot and flower up to 5.46, 4.74 and 1.37 mg kg^?1and lead accumulation up to 16.11, 13.44 and 3.17 mg kg^?1, respectively at Naini dump site, Allahabad (S₃). The treatment showed maximum remediation efficiency for Cd (RR = 0.676%) and Pb (RR = 0.202%) at Mumfordganj contaminated site (S₂). However, the above parameters were also observed at par with the treatment T₅ [2.5 g kg^?1oilcake manure +2 g kg^?1 humic acid]. Applied EDDS altered chlorophyll–a, chlorophyll–b, and carotene contents of plants while application of oilcake manure enhanced their contents in plant by 3.73–8.65%, 5.81–17.65%, and 7.04–17.19%, respectively. The authors conclude that Calendula officinalis L has potential to be safely grown in moderately Cd and Pb-contaminated soils and application of hyperaccumulator oilcake manure boosts the photosynthetic pigments of the plant, leading to enhanced clean-up of the cadmium and lead-contaminated soils. Hence, the hyperaccumulator oilcake manure should be preferred over chelates for sustainable phytoremediation through soil-plant rhizospheric process.     

Phallus impudicus loaded with γ-Fe2O3 as solid phase bioextractor for the preconcentrations of Zn(II) and Cr(III) from water and food samples

We investigated the application of fungus Phallus impudicus loaded γ-Fe₂O₃ nanoparticles as a biosorbent for magnetic solid phase extractions of trace levels of Zn(II) and Cr(III) ions from natural samples before their measurements by inductively coupled plasma optical emission spectrometry. The characterization of magnetized P. impudicus was performed using the scanning electron microscope, the energy dispersive X-ray and Fourier transform infrared spectroscopy. Important experimental factors were investigated. The experimental results fitted well to the Langmuir adsorption model and pseudo-second order kinetic model. Limit of detections of targeted ions by magnetic solid phase extraction method based on use of P. impudicus were found as 10.5 ngL⁻¹ and 12.6 ngL⁻¹ respectively for Cr(III) and Zn(II). The sorption capacities of the biosorbent were 22.8 mgg⁻¹ for Cr(III) and 25.6 mgg⁻¹ for Zn(II). The preconcentration factors were achieved as 100 for both of ions. RSDs for inter- and intraday precisions were found as lower than 2.0% and 2.1% respectively for both of targeted ions. The accuracy of the recommended process was tested by recovery measurements on the certificated reference materials and successfully applied for quantification recoveries of Cr(III) and Zn(II) ions from water and food samples.     

Osteotoxicity of cadmium and lead in HOS TE 85 and ROS 17/2.8 cells: relation to metallothionein induction and mitochondrial binding

Epidemiological, experimental and clinical data indicate that cadmium and lead are osteotoxins in man and other species. The relative sensitivities of a clonal human osteosarcoma cell line (HOS TE 85) and a clonal rat osteosarcoma cell line (ROS 17.28) to the cytotoxic effects of cadmium and lead were tested in serum-free media without added growth factors. The rat osteosarcoma cells were more sensitive to cadmium with cytotoxicity and inhibition of proliferation at 0.25 versus 0.75 and 1.0 mol l^– cadmium, respectively, for human osteosarcoma cell lines. The lower sensitivity to cadmium of human osteosarcoma cells is attributed, at least partly, to induction of metallothionein synthesis by cadmium and zinc in this cell line; in the rat osteosarcoma cell line, they do not induce metallothionein synthesis. Human osteosarcoma cells were more sensitive than rat osteosarcoma cells to lead with inhibition (IC₅₀) of proliferation at 4 mol l^– lead and cytotoxicity at 20 versus 6 and over 20 moll^– lead, respectively, for these variables in rat osteosarcoma cells. Both cells lines attained the highest lead concentration in the 15 000 × g (mitochondrial) fraction. The lead in the mitochondrial, microsomal, nuclear and cytosolic fractions of the human cell line did not decrease during 24 h post-washout. Binding of lead was much less stable in the less sensitive rat cells, with 50–100% loss of mitochondrial, microsomal and nuclear lead during 24 h post-washout.     

Cations and Anions as Modifiers of Ryanodine Binding to the Skeletal Muscle Calcium Release Channel

Rate and equilibrium measurements of ryanodine binding to terminal cysternae fractions of heavy sarcoplasmic reticulum vesicles demonstrate that its activation by high concentrations of monovalent salts is based on neither elevated osmolarity nor ionic strength. The effect of the ions specifically depends on their chemical nature following the Hofmeister ion series for cations (Li⁺ < NH⁺ ₄ < K⁻∼ Cs⁺≤ Na⁺) and anions (gluconate⁻ < Cl⁻ < NO₃ ⁻∼ ClO₄ ⁻∼ SCN⁻) respectively, indicating that both are involved in the formation of the salt-protein complex that can react with ryanodine. Activation by rising salt concentrations exhibits saturation kinetics with different dissociation constants (25–11 m) and different degrees of cooperativity (n= 1.5–4.0) for the respective salts. Maximal second order binding rates between 40,000 and 80,000 (m ⁻¹· sec⁻¹) were obtained for chlorides and nitrates of 1a group alkali ions with the exception of lithium supporting only rates of maximally 10,000 (M⁻¹· sec⁻¹). The nitrogen bases, NH⁺ ₄ and Tris⁺, in combination with chloride or nitrate, behave divergently. High maximal binding rates were achieved only with NH₄NO₃. The dissociation constants for the ryanodine–protein complexes obtained by measurements at equilibrium proved to depend differently on salt concentration, yet, converging to 1–3 nm for the applied salts at saturating concentrations. The salts do not affect dissociation of the ryanodine protein complex proving that the effect of salts on the protein's affinity for ryanodine is determined by their effect on the on-rate of ryanodine binding. ATP and its analogues modify salt action resulting in elevated maximal binding rates and reduction or abolition of binding cooperativity. Linear relations have been obtained by comparing the rates of ryanodine binding at different salt concentrations with the rates or the initial amplitudes (15 sec) of salt induced calcium release from actively loaded heavy vesicles indicating that the various salts promote specifically and concentration dependently channel opening and its reaction with ryanodine. Received: 9 February 1998/Revised: 24 April 1998     

Characterisation of acidic sites of Pseudomonas biomass capable of binding protons and cadmium and removal of cadmium via biosorption

Summary The ability of Pseudomonas aeruginosa to accumulate Cd(II) ions from wastewater industries was experimentally investigated and mathematically modelled. From the potentiometric titration and non-ideal competitive analysis (NICA) model, it was found that the biomass contains three acidic sites. The values of proton binding (pK _i =1.66±3.26×10⁻³, 1.92±1.63×10⁻⁴ and 2.16±3.79×10⁻⁴) and binding constant of cadmium metal ions (pK _M1=1.99±2.45×10⁻³ and pK _M2=1.67±4.08×10⁻³) on the whole surface of biomass showed that protonated functional groups and biosorption of Cd(II) ions could be attributed to a monodentate binding to one acidic site, mainly the carboxylic group. From the isothermal sorption experimental data and Langmuir model, it was also found that the value of Langmuir equilibrium (pK _f) constant is 2.04±2.1×10⁻⁵ suggesting that the carboxyl group is the main active binding site. In addition, results showed that the maximum cadmium capacity (q _max) and affinity of biomass towards cadmium metal ions (b) at pH 5.1 and 20 min were 96.5±0.06 mg/g and 3.40×10⁻³± 2.10×10⁻³, respectively. Finally, interfering metal ions such as Pb(II), Cu(II), Cr(III), Zn(II), Fe(II), Mn(II), Ca(II) and Mg(II) inhibited Cd(II) uptake. Comparing the biosorption of Cd(II) by various Pseudomonas isolates from contaminated environment samples (soil and sewage treatment plant) showed that maximum capacities and equilibrium times were different, indicating that there was a discrepancy in the chemical composition between biomasses of different strains.     

Determination of trace amounts of total dissolved cationic aluminium species in environmental samples by solid phase extraction using nanometer-sized titanium dioxide and atomic spectrometry techniques

Nanometer-sized titanium dioxide was used as a solid-phase extractant for the separation and preconcentration of trace amounts of Al(III) prior to its determination by electrothermal atomic absorption spectrometry (ET AAS) and inductively coupled plasma optical emission spectrometry (ICP OES). The optimal conditions for the proposed solid phase extraction (SPE; 50 mg TiO₂, 10 min extraction time, pH 6.0, HCl and HNO₃ as eluents) and ET AAS measurement (1500 °C pyrolysis and 2600 °C atomization temperatures, Mg(NO₃)₂ as matrix modifier) were obtained. The adsorption capacity of TiO₂ was 4.1 mg Al g⁻¹ TiO₂. Two modes of the proposed procedure were compared, (I) batch and elution mode with the elution of Al from TiO₂ phase by nitric or hydrochloric acid, and (II) batch and slurry mode (without elution) with the direct TiO₂ phase-slurry sampling. Finally, the batch and slurry mode of nanometer-sized TiO₂ SPE with slurry ET AAS detection and quantification was preferred and used for the determination of trace amounts of total dissolved cationic Al species in synthetic and natural water samples. The method accuracy was checked by the analysis of lake water CRM TMDA-61 and by the technique of analyte addition (sample spiking). Under the optimal conditions, the calibration curve for batch and slurry TiO₂ SPE with a 10-fold preconcentration was linear up to 40 μg L⁻¹ Al. The limit of detection (LOD) and the limit of quantification (LOQ) was 0.11 μg L⁻¹ Al and 0.35 μg L⁻¹ Al, respectively, with a preconcentration factor of 20 and a relative standard deviation (RSD) lower than 5%.     

Synthesis of coordination compounds via dehalogenation of zinc bromoacetate in presence of some amines

The dehalogenation reactions of pure zinc bromoacetate and its mixtures with hexamethylenetetramine, 2,2′-bipyridine, 1,10-phenanthroline were studied in water solutions. Due to the decomposition of hexamethylenetetramine during reaction, the cadmium bromoacetate-hexamethylenetetramine system was also studied. The four new coordination compounds, catena-[bis(μ₂-α-hydroxyacetato-κ³O¹,O²:O^1′)-zinc], catena[μ₂-1-(8-carboxylateethyl)-1,3,5,7-tetra-aza-adamantan-1-ium-N,O′]-dibromo-cadmium, dibromo-(2,2′-bipyridine-N,N′)-zinc, dibromo-(1,10-phenanthroline-N,N′)-zinc were synthesised and characterised by elemental and thermal analysis, IR and UV-vis spectroscopy, and X-ray crystallography. All compounds are air stable and well soluble in water. The zinc hydroxyacetate creates two-dimensional 4-c uninodal net. The zinc atoms are four and six coordinated and the cadmium atom is five coordinated. The coordination polyhedra of central atoms can be described as octahedron and trapezoidal pyramid for Zn and Cd polymers, respectively, and as trigonal pyramid for ZnBr₂ complexes. The bond valences considerations show that the chelating amines are bonded almost two times stronger to the central atoms than the chelating carboxylate groups. In the structures of polymeric compounds exist O-H?O, C-H?O, C-H?N and C-H?Br hydrogen bonds. The IR spectra show typical vibrations for chelating amine molecules. The thermal decomposition of studied compounds proceeds via multiple steps with gradual evolution of ligands.     

Trace metals complexation behavior with root exudates induced by salinity from a mangrove plant Avicennia marina (Forsk.) Vierh

This study investigated the characteristics of exudates from mangrove plant Avicennia marina seedling roots under 0, 200 and 600?mM NaCl treatments and their complexation behavior with trace metals using excitation emission matrix (EEM) fluorescence spectrometry. Two fulvic-like fluorescence peaks, namely peak A (Em = 440?nm, Ex = 250?nm, UV fulvic-like compounds) and peak B (Em = 440?nm, Ex = 340?nm, visible fulvic-like compounds) were identified. The fluorescence intensities of peak A and peak B were enhanced by increasing salinity. Furthermore, the fluorescence of both peaks could be quenched by the ions of copper (Cu²⁺), manganese (Mn²⁺) and cadmium (Cd²⁺). Conditional stability constant (logK_a) exhibited that binding capacity of both peak A and peak B with trace metals are Cu²⁺?>?Mn²⁺?>?Cd²⁺ in the range from 2.21 to 4.01. Besides, Hill coefficient (n) >1 for Cu²⁺ but n?<?1 for Mn²⁺ and Cd²⁺. The results of high n and high logK_a for Cu²⁺ rather than Mn²⁺ and Cd²⁺ indicate that the fulvic-like compounds in root exudates of A. marina have maximum potential for Cu²⁺ complexation compared to Mn²⁺ and Cd²⁺, suggesting the fulvic acids in root exudates of A. marina have strong complexation with Cu²⁺ rather than Mn²⁺ and Cd²⁺.