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The sorption of several metal ions on a solid, iminodiacetic based material, the Empore™ chelating membrane, is considered. Determination of the acid-base properties, kinetic of metal sorption and complexing properties, in solutions with different composition is undertaken. The results are compared with those obtained using the classical iminodiacetic resin Chelex 100 in beads. In particular, Cd(II), Fe(III), Pb(II), and Zn(II) are considered. The Gibbs–Donnan, the usual model we used to explain the protonation and the metal sorption on chelating sorbent, is applied also in the present study. On the other hand, the kinetic models selected to describe our data are the two widely applied for fitting ion-exchange data: the Homogeneous Particle Diffusion Model and the Sharing Core (Shell Progressive) Model. In general no significant differences between membrane and resin are found in the thermodynamic properties, but for some metals the kinetics of the sorption on the membrane is slower.

Euphorbiaceae barks are known to contain an appreciable amount of polyphenolic compounds responsible for several biological activities. Preliminary extraction from Bridelia grandis stem bark afforded high content of polyphenols, determined by spectrophotometric methods such as Folin-Ciocalteu (for total phenols, TP) and n-butanol-HCl (for condensed tannins, CT). A preliminary Plackett-Burman screening design was used to identify the key factors that influence the TP and CT extraction. Between all the variables known to influence the extraction from vegetable matrixes, six were selected; maceration was chosen as traditional extraction methodology. To investigate the effect of solvents and extraction method, methanol, acetone 70% (v/v in water), centrifugation and ultrasound were chosen. A full factorial design 2(3) was applied to optimize the extraction procedure. The responses were obtained analyzing the extracts for their TP and CT contents determined by the above-mentioned spectrophotometric methods. The results confirm that, within the explored domain, the optimum solvent is methanol and the optimum method is one-cycle centrifugation. Finally, it was also compared with the effect of maceration on the considered responses. It has never given results better than centrifugation, whereas in the case of CT it represents an advantage to employ a three-cycle centrifugation instead of one.

The sorption of copper(II) on a solid, iminodiacetic based, chelating material, the Empore membrane, in alcoholic solutions is considered. Determination of the acid-base properties, kinetic of metal sorption and complexing properties, in solutions with different percentages of ethanol, ranging from 0 to 40% is undertaken. The results are compared with those obtained using the classical iminodiacetic resin Chelex 100 in beads. No significant differences are found in the thermodynamic properties, but the kinetics of the metal sorption on the membrane is slower and a dependence of the process rate with the alcoholic content is observed. In the present investigation, the detection of copper(II) species both in alcoholic Italian distillate "grappa" and in its intermediate product ("flemma"), is carried out by the Resin Titration (RT) method using, as competitive reagent, the Empore membrane. To validate the procedure, synthetic solutions containing different percentages of ethanol are analysed.

Objective: To test the hypothesis that there is no difference in the amounts of chromium released from new stainless steel brackets, recycled stainless steel brackets, and nickel-free (Ni-free) orthodontic brackets. Materials and Methods: This in vitro study was performed using a classic batch procedure by immersion of the samples in artificial saliva at various acidities (pH 4.2, 6.5, and 7.6) over an extended time interval (t1 = 0.25 h, t2 = 1 h, t3 = 24 h, t4 = 48 h, t5 = 120 h). The amount of chromium release was determined using an atomic absorption spectrophotometer and an inductively coupled plasma atomic emission spectrometer. Statistical analysis included a linear regression model for repeated measures, with calculation of Huber-White robust standard errors to account for intrabracket correlation of data. For post hoc comparisons the Bonferroni correction was applied. Results: The greatest amount of chromium was released from new stainless steel brackets (0.52 ± 1.083 μg/g), whereas the recycled brackets released 0.27 ± 0.38 μg/g. The smallest release was measured with Ni-free brackets (0.21 ± 0.51 μg/g). The difference between recycled brackets and Ni-free brackets was not statistically significant (P = .13). For all brackets, the greatest release (P = .000) was measured at pH 4.2, and a significant increase was reported between all time intervals (P < .002). Conclusion: The hypothesis is rejected, but the amount of chromium released in all test solutions was well below the daily dietary intake level.

Amperometric sensors for nonelectroactive substances have been obtained by contacting glassy carbon or graphite electrodes with molecularly imprinted polymeric (MIP) membranes, 300–0.6 μm thick. The thicker membranes were self standing membranes while the thinner ones were prepared by drop coating on a graphite electrode. Cyanuric acid and atrazine were the target compounds. Determinations were carried out at −850 mV (vs. Ag/AgCl(sat)) in aqueous solution at pH 1.5, followed by a step at +500. The current linearly depends on the concentration of the template molecule in aqueous solution up to 10−4 M. For atrazine the current increases with the concentration, while for cyanuric acid the current intensity decreases. Not any current variation was observed on bare carbon electrodes, nor on electrodes covered with a nonimprinted membrane. The detection limit was 9×10−7 M for atrazine and 2×10−5 M for cyanuric acid. The sensors response was very fast and selective for the corresponding template.

Different natural water samples were investigated to determine the total concentration and the distribution of species for Cu(II), Pb(II), Al(III) and U(VI). The proposed method, named resin titration (RT), was developed in our laboratory to investigate the distribution of species for metal ions in complex matrices. It is a competition method, in which a complexing resin competes with natural ligands present in the sample to combine with the metal ions. In the present paper, river, estuarine and seawater samples, collected during a cruise in Adriatic Sea, were investigated. For each sample, two RTs were performed, using different complexing resins: the iminodiacetic Chelex 100 and the carboxylic Amberlite CG50. In this way, it was possible to detect different class of ligands. Satisfactory results have been obtained and are commented on critically. They were summarized by principal component analysis (PCA) and the correlations with physicochemical parameters allowed one to follow the evolution of the metals along the considered transect. It should be pointed out that, according to our findings, the ligands responsible for metal ions complexation are not the major components of the water system, since they form considerably weaker complexes.

The sorption of inorganic lead(II) on two cationic resins containing different complexing groups, the iminodiacetic Chelex 100 and the carboxylic Amberlite CG-50, was investigated. The Gibbs-Donnan model was used to describe and predict the sorption through the determination of the intrinsic complexation constants. These quantities, even though non-thermodynamic, characterize the sorption as being independent of experimental conditions. The sorption mechanism for metals on complexing resins was also studied by adding a competitive soluble ligand that shifts the sorption curves to higher pH. The ligand competes with the resin for complexation with the metal ion. Lead(II) is strongly sorbed on Chelex 100 through the formation of two complexes in the resin phase: MHL with log 10β111i=−0.3 and ML with log 10β111i=−3.7. The presence of the competitive ligand in solution allows for the determination of a third complex. Furthermore, on Amberlite CG-50 the sorption is rather strong and involves the formation of the complex ML, in more acidic solution, with log 10β110i=−2.0. In the presence of the ligand PyDA, the ML(OH) complex was characterized by log 10β11−1i=−5.6. In all the experiments the hydrolysis reactions in the aqueous phase are considered quantitatively.

We synthesized a solid sensory material for the extraction, detection and quantification of iron(III) in aqueous media. The material is a film-shaped colorless polymer membrane that exhibits gel behavior. The Fe(III) extraction and sensing characteristics are imparted by a new monomer derived from a natural product (i.e., Kojic acid), which exhibits chelating properties toward Fe(III). The sorption of Fe(III) on the membrane in water has been thoroughly characterized, including the sorption kinetics, sorption isotherms and profiles as a function of the pH. Fe(III) sorption followed pseudo first-order kinetics and required approximately 30 min to reach equilibrium. The maximum sorption capacity was approximately 0.04 mmol/g, and the sorption isotherms are well modeled by the Langmuir equation. The complexes that were found in the solid phase are in good agreement with those previously identified in the aqueous phase. Moreover, the sorption is highly specific (i.e., a recognition process) and results from the formation of a colored complex (iron(III)-Kojic acid derivative moieties). Therefore, the colorless sensory membrane turns red upon immersion in aqueous solutions containing Fe(III). The color output allows for both the qualitative visual determination of the Fe(III) concentration as well as also titration of Fe(III) using a) a UV/vis technique (limit of detection of 3.6 × 10−5 M; dynamic range of five decades, lower concentration = 1.65 × 10−6 M) and b) a computer vision-based analytical chemistry approach via color definition of the sensory membrane (RGB parameters) obtained from an image recorded with a handy device (e.g., a smartphone) (limit of detection of 2.0 × 10−5 M)., Spanish Ministerio de Economía y Competitividad-Feder(MAT2014-54137-R) and by the Consejería de Educación—Junta deCastilla y León (BU232U13).

Presented hereafter is the pilot-study of the applicability of resin titration (RT) to mixed solvents in regard to the studies of metal distribution in wines – a beverage that has attracted great attention and that has been extensively studied in the recent years. The RT method of studying the distribution of species is based on the determination of the concentration of metal ions sorbed on the iminodiacetic resin Chelex 100 at different V / w (solution volume/mass of resin). The total metal ion present in the considered solution and the free metal ion are estimated from the titration curves. The method, already applied for water solutions, was tested here in mixed solvent media, at the pH around 3, with known amounts of copper(II) and ligands with different complexing properties. Satisfactory results have been obtained and commented critically. In the application of the RT method, the protonation and the exchange reactions of copper(II) with the considered sorbent were investigated in 12% ethanol, in KCl 0.1 and 1.0 M solutions, according to a well established procedure. Finally, a white grape wine (Riesling) from a winery in Oltrepo Pavese was analyzed with RTs. In the sample obtained before processing the wine, 50% of the total Cu(II) (∼18 μM) was combined with ligands with log α M equal to 3.3; in the final product, the total Cu(II) was 4 μM, almost totally complexed. According to these findings, the ligands accountable for the copper complexation were not the major components in the wine, as they formed considerably weaker complexes.

A molecular imprinted polymer (MIP) membrane for atrazine, not containing macropores, was synthesized and implemented in a potentiometric sensor. It is expected to work like a solid ISE (where the specific carrier are the imprinted sites) the specific carrier being the imprinted site. The active ion is the protonated atrazine, positively charged. To form this species the determination is carried out in acidic solution at pH lower than 1.8, in which atrazine is prevalently monoprotonated. At these conditions the membrane potential increases with atrazine concentration over a wide concentration range (3 × 10 −5 to 1 × 10 −3 M). The slope of the function E versus log c is about 25 mV/decade, showing that the atrazine form sorbed on MIP is the biprotonated one. The detection limit is determined by the relatively high concentration of atrazine released by the membrane in the sample solution at the considered conditions. It seems to be independent of the atrazine concentration in the internal solution of the sensor, but it depends on the acidity of the solution. The response time is less than 10 s and the sensor can be used for more than 2 months without any divergence.

Very stable aluminium complexes may be present in natural waters, which can be detected only using appropriate methods. One of them is the resin titration based on the sorption of aluminium on a strongly sorbing resin, Chelex 100. It was here used to detect strong aluminium complexes, and to characterize them by determining their concentration, and the corresponding stability constant. High and low salinity waters were sampled in different sites in the North of Italy. In all the samples aluminium complexes with high stability constant, up to 10 17.4 M −1 in the less acidic solution, were detected. The stability constant depends mainly on the solution acidity, increasing with increasing pH up to 7. The concentration of the ligands responsible for the strong complexation is similar to that of aluminium (from 0.5 to 1.5 μM), or somewhat lower in the case of estuarine and sea waters. A small fraction of aluminium (from 0% to 2%) in freshwaters, higher in estuarine and sea waters (14% and 10%, respectively), is present in weakly bound forms which could also be the hydrolysis products. The conditional constants of the strong complexes were determined for the different samples examined. They were found to be slightly lower in the case of the high salinity waters, in which a value of 10 16.1 M −1 at pH 7.5 was obtained. This is probably due to the higher ionic strength in marine water, which strongly influences the complexation of trivalent metal ions, as seen for example also in the hydrolysis. It could be deduced that similar substances, but at different concentration, would be responsible for the aluminium complexation in the sea and freshwaters here examined. They could be natural organics like fulvic substances, or better some particular complexing sites in this substances with very high affinity for aluminium.

A new procedure is presented for the determination of the ligands of copper(II) in natural waters, based on titration with the metal ion, monitored by measuring the concentration of copper(II) sorb...

The detection and investigation of metal ions bound in strong complexes in natural waters is a difficult task, due to low concentration of the metal ions themselves, and also of the strong ligands, which, moreover, are often not of a well-defined composition. Here, a method is proposed for the investigation of the speciation of metal ions in natural waters.It is based on the sorption of metal ions on strongly sorbing ion exchange resins, i.e. complexing resins. For this reason the method is called Resin Titration. It has been shown in previous investigations that the concentration of metal ion totally sorbed by a particular resin, and its reaction coefficient in the solution phase in the presence of the resin, can be determined from the sorption data using a simple relationship. Here, a data treatment (the Ruzic linearization method) is proposed for also determining the concentration of the ligands responsible for the complex in equilibrium with the resin.The method was applied to data obtained by Resin Titration of a freshwater and a seawater. Copper(II) and aluminium(III) were considered, using Chelex 100 as a titrant, due to its strong sorbing properties towards these metal ions. The results were: the total metal concentration in equilibrium with the resin, the side reaction coefficients, and the concentration of ligands. In all these cases the ligands forming very strong complexes were found to be at concentration lower than that of the metals.The Ruzic linearization method allows the determination of the concentration of the ligands forming very strong complexes in equilibrium with Chelex 100. The reaction coefficient was better determined by the calculation method previously proposed for RT. The ligands responsible for the strong complexes were found to be at low concentration, often lower than that of the metal ions considered. The metal in the original sample is partly bound to these ligands, since the complexes are very strong. Only a part of the metal is linked to weaker ligands, or free.

The sorption of uranium(VI) on two cationic resins containing different complexing groups, the iminodiacetic resin Chelex 100 and the weak carboxylic resin Amberlite CG-50, was investigated. The Gibbs-Donnan model was used to describe and to predict the sorption through the determination of the intrinsic complexation constants. These quantities, even though non-thermodynamic, characterize the sorption as being independent of experimental conditions. The sorption mechanism of the metal on the complexing resins was also studied by adding a competitive soluble ligand that shifts the sorption curves to higher pH values. The ligand competes with the resin for the complexation with the metal ion. Uranium is also strongly sorbed on Chelex 100 at very acid pH, through formation of two complexes in the resin phase: ML with log beta(110i)=-1.16, in more acidic solution, and ML(2 )with log beta(120i)=-5.72. Only the presence of the competitive ligand in solution makes the determination of the second complex possible. Also on Amberlite CG-50 the sorption is strong and involves the formation of the complex ML(2), in more acidic solution, with log beta(120i)=-3.16. In the presence of the ligand EDTA, the complex ML(2)(OH)(2 )was characterized with log beta(12-2i)=-5.15. In all the experiments the hydrolysis reaction in the aqueous phase was quantitatively considered.

The complexation properties of some drinking waters for U(VI), Al(III) and Cu(II) are determined by ligand titration (LT) with the metal ions, using a new method for monitoring, i.e. the sorpion of metal ion on complexing resins. The concentration of the free metal ion in solution is evaluated from the concentration of sorbed metal ion and from the quantity K * , which is the ratio of the concentration of the metal ion sorbed on the resin to the concentration of free metal ion in solution, and can be independently evaluated. The concentration of the ligands in solution (c I ) and the conditional stability constant (K M(I) ) are obtained by the Ruzic linearization. Different resins, i.e. the iminodiacetic resin Chelex 100, the carboxylic resin Amberlite CG 50 and the anion exchange resin AG1X8 were used for monitoring the titration, since they have different sorbing properties, and in principle they allow the detection of different ligands. Ligands at low concentration and with very high complexation constants were detected in the considered samples. Particularly in the case of U(VI), they are able to complex the metal ion much more strongly than the ligands that are usually considered in aqueous solution, i.e. carbonate and hydroxyl.

The solid-phase extraction (SPE) of copper(II) and aluminium(III) from fresh waters on an ion-exchange complexing resin containing iminodiacetic groups (Chelex 100) has been examined. Quantitative recovery of the metal ions was related to the breakthrough profile that, for some samples, could not be evaluated directly. A method is suggested for evaluation, instead, of the sorption curves, on the basis of passing different volumes of sample through the column. This enables evaluation of important properties, for instance the central point of the breakthrough curve, V t . The column used was a small one, containing 0.10 g dry Chelex 100. The metal ion was eluted with a small volume of acid solution, 10 mL of 0.5 mol L -1 HNO 3 ; this resulted in good preconcentration factors. For copper(II) it was found that fresh waters of similar composition could have different V f in the same column. This was ascribed to different reaction coefficients (α M(I) ) of copper(II) in the considered samples, which affects V f . By use of the proposed SPE procedure it is possible to evaluate the reaction coefficient of copper(II). The values of α M(I) for two different drinking waters at pH 7.7 were found to be 3.70 x 10 12 and less than 4.40 x 10 11 . Similar results were obtained for aluminium(III).

A number of reports have appeared in literature calling attention to the depletion of essential metal ions during chelation therapy on β-thalassaemia patients. We present a speciation study to determine how the iron chelators used in therapy interfere with the homeostatic equilibria of essential metal ions. This work includes a thorough analysis of the pharmacokinetic properties of the chelating agents currently in clinical use, of the amounts of iron, copper and zinc available in plasma for chelation, and of all the implied complex formation constants. The results of the study show that a significant amount of essential metal ions is complexed whenever the chelating agent concentration exceeds the amount necessary to coordinate all disposable iron —a frequently occurring situation during chelation therapy. On the contrary, copper and zinc do not interfere with iron chelation, except for a possible influence of copper on iron speciation during deferiprone treatment.

The development of a sensor based on the functionalization of common filter paper with deferoxamine (DFO) is proposed with the prospect to produce a solid phase for iron(III) and vanadium(V) sensing. The main features of this sensor are the simplicity of operation, good sensitivity and feasible applicability to real samples without the need of pre-treatment procedures. DFO was selected not only for it is easily anchored to the solid support, but also because it forms colored complexes with iron(III) and vanadium(V); hence, the developing of a simple colorimetric sensor can be considered. In particular, an innovative and economic way to perform colorimetric measurements using a desktop scanner is described. A complete characterization of the functionalized material is also reported.

A competion method is proposed to characterize natural metal complexes present in a high salinity spring water. The competitor is a strong complexing resin containing the iminodiacetic group, Chelex 100. Its sorbing properties towards the metal ions here considered, Cu(II), Mn(II) and Al(III), are well known and could be quantified through K*, the ratio of the concentration of the metal in the resin phase to that of the free metal in solution. It can be calculated for the considered metal ion for the particular experimental conditions. From the fraction of metal experimentally sorbed on the resin it is possible to obtain information about the distribution of the metal in the original water solution. Two different methods are proposed. In the resin titration (RT), different volumes of sample are treated with the same amount of resin. RT allows to determine the total metal concentration and the reaction coefficient of that metal in solution. In the ligand titration (LT), the free metal is added stepwise into the original sample, and the ligand concentration and the complexation constant are determined. This was done by the Ruzic linearization method, modified to take unto account the variation of the pH of the solution. Also the data from RT were elaborated by the modified Ruzic linearization. The study of metal ions distribution among different chemical species by the combined methods is discussed in detail. The three metal ions in the considered high salinity water were found to be mainly combined in complexes with high complexation constant. The concentration of the strong ligands involved was near to that of the metals.

Successful in vivo chelation treatment of iron(III) overload pathologies requires that a significant fraction of the administered drug actually chelates the toxic metal. Increased mobilization of the iron(III) in experiments on animals or humans, most often evaluated from urinary output, is usually used as an assessment tool for chelation therapy. Alternatively, the efficiency of a drug is estimated by calculating the complexing ability of a chelating agent towards Fe(III). The latter is calculated by the pFe value, defined as the negative logarithm of the concentration of the free metal ion in a solution containing 10 μM total ligand and 1 μM total metal at a physiological pH of 7.4. In theory, pFe has to be calculated taking into account all the complexation equilibria involving the metal and the possible ligands. Nevertheless, complexation reactions in complex systems such as serum and urine may hardly be accurately modelled by computer software. The experimental determination of the bioavailable fraction of iron(III) in biological fluids would therefore be of the utmost relevance in the clinical practice. The efficiency of the therapy could be more easily estimated as well as the course of overload pathologies. In this context, the aim of the present work was the development of a sensor to assess the free iron directly in biological fluids (urine) of patients under treatment with chelating agents. In the proposed device (DFO-MS), the strong iron chelator deferoxamine (DFO) is immobilized on the MCM-41 mesoporous silica. The characterization of the iron(III) sorption on DFO-MS was undertaken, firstly in 0.1 M KNO3, then directly in urine samples, in order to identify the sorption mechanism. The stoichiometry of the reaction in the solid phase was found to be: with an exchange constant (average value) of log βex = 40(1). The application of DFO-MS to assess pFe in SPU (Simulating Pathology Urine) samples was also considered. The results obtained were very promising for a future validation and subsequent application of the sensor in samples of patients undergoing chelation therapy.

In this work we present a multichannel chemical sensor based on Surface Plasmon Resonance (SPR) in a Plastic Optical Fiber (POF), for the detection of metal ions. The SPR sensing platform was realized removing the cladding of a plastic optical fiber along half circumference, spin coating on the exposed core a buffer of Microposit S1813 photoresist, and finally sputtering a thin gold film by using a sputtering machine. The planar gold layer can be employed for the preparation of a Self Assembled Monolayer (SAM) with specific binding receptor. In the present study two different ligands for Fe(III) and Cu(II) are linked on the gold surface obtaining two SAM-POF sensors. © 2014 AEIT.

Sorption mechanism of bivalent metal ions on a weak cationic resin containing the carboxylic group is studied. The Gibbs-Donnan model is used to describe and then to predict the sorption through the determination of the intrinsic complexation constants. These quantities characterize the sorption being independent of experimental conditions. They are determined according to a well established procedure and using a recently proposed iterative method for calculation of counter ion concentration in the resin phase. Sorption mechanisms are also studied adding appropriate soluble ligands whose complexing properties are exactly known to the solution containing the resin and the metal ion. Competing with the resin for the complexation of the metal, they shift the sorption curve to higher pH and often this allows detecting other complexes between the metal and the resin. In this way for Mn(II), besides the 1:1 complex formed in the more acidic solution, with logbeta(110)=-4.55, the complex ML(2), characterized by logbeta(120)=-9.80, is found; for Cd(II), besides the ML complex, with logbeta(110)=-3.01, at pH higher than 7, the specie MLOH with logbeta(11-1)=-8.28. For Cu(II) the complex ML(2) is detected, confirming previous findings, with logbeta(120)=-7.24. In the presence of two different ligands, sulphosalicylic and malonic acid, a different complex, ML(2)OH, is identified, with the same intrinsic complexation constant for the two ligands, logbeta(12-1)=-13.35. As expected from the model, the intrinsic complexation constants, especially for the 1:1 complex, are in a good agreement with the complexation constants of acetic acid.

The deprotonation of quinolic resin P-127 and iminodiacetic resin Amberlite IRC-718 has been studied. The process of salt transfer into the resin phase is considered to be an important contributor to the deprotonation process. Estimation of the salt transfer was based on the principle of equal activity of the salt in both phases at equilibrium. Two assumptions were made: sorbed alkali metal ions are not associated with functional groups, while all hydrogen ions are associated with functional groups. The associated hydrogen ions and functional groups do not contribute to the internal ionic strength value. Two thermodynamic models, describing the deprotonation of ion-exchange resin, were used and compared: the Gibbs−Donnan-based model of Bukata and Marinsky and the model proposed by Erik Hogfeldt. Thermodynamic characteristics of the resins' deprotonation are obtained using two different thermodynamic approaches. Hogfeldt's three-parameter model provides a better agreement with experimental data. The fitt...

The intrinsic protonation and complexation constants of an ion-exchange complexing resin, previously determined in condition of trace metal ions on the basis of the Gibbs–Donnan model of ion-exchange resins, were here used to evaluate the concentration of metal ions sorbed on the resin when the metal ion is in excess. The resin considered was a commercial one, containing carboxylic groups at a concentration of 10 mmol g−1 of dry resin. Metal ions complexable by the active groups present in the resin phase, i.e. alkaline earth metals and cadmium(II), were investigated, together with a not complexable metal ion, sodium, which enters in the resin phase only by diffusion and ion-exchange. The calculation method is an iterative one, taking into account the diffusion and ion-exchange in the case of the not complexable metals, and the complexation in the case of the complexable metal ions. The concentration of metals in the resin phase calculated by the proposed procedure was compared with that obtained experimentally in some representative solutions at different composition and acidity. The agreement was acceptable, showing that the intrinsic complexation constants are of help not only in conditions of trace metal, but also for evaluations at completely different conditions. In the case of complexable metal ions it was shown that the complexation in the resin phase is the most important sorption mechanism, even if ion-exchange takes place at high acidity, when the complexation is negligible.

A chelating resin containing iminodiacetic groups, Chelex 100 which is often employed for sorbing metal ions from complex matrices, was used for separating and preconcentrating heavy metal ions from seawater samples. The resin titration method was applied for determining the total concentration. The experimental procedure consists of measuring the concentration of the metal sorbed on Chelex 100 from solutions with different ratios volume of aqueous phase/amount of resin. The total metal ion concentration is obtained from the experimental data by a model for the sorption on the resin, the parameters of which are obtained by a non-linear regression procedure. In this way not only the total metal ion concentration can be determined, but also the side reaction coefficient α M(I) , if the sorption equilibria of the considered metal ion on the resin are exactly known, as is the case of Chelex 100 considered here. The resin titration with Chelex 100 was utilized for determining the total metal ion concentration in certified seawater samples and real samples from the Ligurian Sea. It allowed the simultaneous determination of the total concentration of manganese(II), cadmium(II), nickel(II) and copper(II), in acceptable agreement with the certified values. Moreover, the side reaction coefficients of some complex species could be evaluated. They were very high, and strongly dependent on the acidity of the sample solution. For instance, values varying from 10 9 to 10 11 were obtained for copper (II) in the different samples considered, at pH around 7. Chelex 100 is such a strong sorbing substance that it is able to compete with the stable complexes for the combination with the heavy metal ions considered here.

A macroporous resin containing iminodiacetic groups (Lewatit) was investigated for its sorption properties towards proton and nickel(II) and cadmium(II). Different compositions of the aqueous phase, and different temperatures were examined. The stoichiometry, the exchange coefficients and the intrinsic constants of the sorption equilibria were obtained from the experimental data by using the Gibbs-Donnan model for the ion exchange resin. The intrinsic constants were found to be independent of the composition of the solution, so that they were used for characterizing the sorption equilibria. While the first intrinsic protonation constant of the active groups in the resin was found to depend on the temperature, the second one was independent. The sorption equilibrium of nickel in the resin was different from that of cadmium, being ascribable respectively to the formation of the complexes NiL and Cd(HL)(2). inside the resin. Their intrinsic complexation constants were found to be 10(-1.84) and 10(-3.64) at 25 degrees C. Compared to those of another resin with the same active groups, but not macroporous, they are higher. The dependence of the intrinsic constant on the temperature was also different for the two metals, allowing to evaluate a DeltaH degrees of +30.9 and of +13.7 kJ mol(-1) respectively. When a comparison is possible, these values are near to those in aqueous solution for the complexation with ligands of similar structure. These results can be used to achieve metal ion separation based on temperature variations.

The sorption properties of the strong anion exchange resin AG1X8 towards aluminium(III) were investigated in view of the study of the speciation of this metal ion in drinking waters. This was done by determining the side reaction coefficients of the metal ion in the sample solution in the presence of the resin. It was found that aluminium(III) is sorbed on AG1X8 by the formation of Al(OH)3 and Al(OH)−4. The exchange coefficients were determined at different conditions and the intrinsic complexation constants were evaluated on the basis of the Gibbs–Donnan model. From the exchange coefficients the ratio of metal ion sorbed on the resin to the free metal ion in solution, K* was evaluated. It is a measure of the sorbing properties of a resin towards a metal ion at a given pH. AG1X8 was used for the determination of total aluminium(III) concentration in drinking water samples by the resin titration (RT) method at pH 7.5 and 6.2. In the first case the total concentration obtained by RT was equal to that determined directly, showing that all aluminium is either quantitatively sorbed or in equilibrium with AG1X8. The side reaction coefficient αM(I) was evaluated to be around 1012 in the considered drinking water samples at this pH. Not any aluminium(III) was sorbed on AG1X8 from the considered drinking water samples at pH=6.2 suggesting that aluminium is present here as species with αM(I)>107. These results were compared with those obtained using Chelex 100, which is able to sorb aluminium(III) also at pH 6.2. More information about the speciation of aluminium can be obtained by comparing the results from two different sorbing resins.

The Gibbs-Donnan model for ion-exchange resins is used to describe and predict the sorption equilibria of metal ions on chelating resins. These are characterized by their intrinsic complexation constants, which, according to thel model, are related to the complexation constants in solution with ligands having structure similar to that of the active groups in the resin. The intrinsic complexation constants are independent of the experimental conditions, for instance the composition of the solution phase. The model is applied to two different kind of chelating resins: a strong anion exchanger loaded with sulfonated azo dyes, and a weak cation exchanger with iminodiacetic groups (Chelex 100) covalently linked to the mainframe. In most cases the complexation inside the resin exactly corresponds to that in aqueous solution, while sometimes the formation of 1-to-2 complexes is promoted inside the resin. In any case the intrinsic complexation constants allow us to evaluate the exchange coefficients, holding at the particular conditions, by the Gibbs-Donnan model. Thus the sorption and elution of a metal ion by a batch procedure can be predicted. A particular application is described, which is useful in the field of analytical chemistry. It is the determination of total and free metal-ion concentration in an aqueous solution of unknown composition, at very low concentration of metal. This also is made possible by the knowledge of the exchange coefficients at the particular conditions.

A method for the determination of the total metal ion concentration in samples of unknown composition after separation on a chelating resin was applied to the determination of aluminium(III) concentration in real freshwater samples, using Chelex 100 as a sorbing resin. The method, called chelating resin titration, was previously tested on synthetic samples, and allows also the evaluation of the side reaction coefficient [αM(I)] of the metal ion in the presence of the resin, which is useful for the study of metal speciation. To obtain this information, the sorption equilibria of aluminium(III) on Chelex 100 under the experimental conditions must be exactly known. These equilibria were investigated according to a previously reported method, based on the determination of the sorption curves of aluminium on Chelex 100 from solutions of known composition, sometimes containing chelating substances. It was found that the sorption of aluminium on Chelex 100 takes place by formation of three species, AlL, AlL(OH) and Al(OH)3. The corresponding exchange coefficients were determined. Despite the fact that Chelex 100 sorbs aluminium(III) strongly, it was found that the sorption from fresh waters was not quantitative, which was ascribed to the strong complexation of aluminium in the samples considered. The values of αM(I) of aluminium in some freshwater samples at natural pH and acidified up to pH 3 were determined. They were found to be much higher than those ascribable to hydrolysis or to inorganic and organic ligands present in natural waters, being for instance 1012.1 at pH 7.48 and 107.5 at pH 4.88. A similar determination carried out in a 10–3 mol kg–1 sodium chloride solution containing a known amount of aluminium at pH ≈ 8 gave log αM(I) = 14, completely ascribable to hydrolysis, showing that an accurate evaluation can be obtained by the proposed method.

The sorption of some bivalent metal ions on the iminodiacetic resin Chelex 100 was examined in artificial seawater as an example of a complex matrix, and in the presence of an organic chelating substance in the aqueous phase. The curves reporting the fraction of sorbed metal ions in function of the solution pH were determined experimentally under different conditions and the exchange coefficients were calculated. The intrinsic complexation constants, which are independent of the conditions, were evaluated on the basis of the Gibbs-Donnan model for the resin and agree with those previously obtained in the case of the sorption of the same metals on Chelex 100 from solutions of simpler composition. In some instances the intrinsic complexation constants were similar to the corresponding complexation constants in aqueous solution, while in other cases they were different, depending on the activity coefficient ratio of the species inside the resin. It has been demonstrated that the method derived from the Gibbs-Donnan model can be used for describing and predicting the sorption equilibria also from complex solutions, if all the equilibria set up in the considered system are known.

Ion selective electrodes (ISE) for organic ions are in principle suitable for rapid in situ determinations. A critical point in the development of ISEs is to find out specific receptors. In this investigation the possibility of developing solid state ISEs with molecularly imprinted acrylic polymers (MIP) as a recognition element was investigated. As a proof case, an all-solid-state ISE for dopamine (DAH+) was prepared. In order to attain a real miniaturization of the whole measuring device, the reference electrode too was an all-solid-state one, based on the same polymer used for the working electrode but in the absence of template. A screen printed graphite electrode modified with multiwalled carbon nanotubes as an ion to electron transducing layer was used as conducting substrate. The cell potential linearly increases at dopamine concentration higher than 10−4 M, but the sensibility is less than nernstian (16 mV/dec). The sensor is very selective for the template.

The chelating properties toward iron(III) and aluminium(III) of variously substituted salicyl-aldehydes and salicylic acids have been evaluated, together with the effect of methoxy and nitro substituents in ortho and para position with respect to the phenolic group. The protonation and iron and aluminium complex formation equilibria have been studied by potentiometry, UV-visible spectrophotometry and (1)H NMR spectroscopy. The overall results highlight that salicyl-aldehydes present good chelating properties toward iron(III), with pFe ranging from 14.2 with nitro to 15.7 with methoxy substituent, being ineffective toward aluminium; the pFe values for salicylic acids are generally lower than those for salicyl-aldehydes, and about 4 units higher than the corresponding pAl values. The effect of the two substituents on the chelating properties of the ligands can be rationalized in terms of the Swain-Lupton treatment which accounts for the field and resonance effects. The structural characterization of the 1:2 iron complex with p-nitro salicylic acid shows that iron(III) ion exhibits an octahedral surrounding where two salicylate chelating ligands supply two O-phenolate and two O-carboxylate donor atoms in a roughly equatorial plane. The trans-apical sites are occupied by two aqua ligands.

A method for determining the total concentration of a metal ion originally present in a solution (c tot ) and the ratio of total to free metal ion (Z M ) is proposed. It consists of putting different aliquots of the sample (V) in contact with the resin (w) in batch, by keeping the acidity constant, and determining the concentration of the sorbed metal ion c. Then 1/c is plotted against V/w, and c tot and Z M are calculated from the straight line obtained. The chemical model that allows evaluation of the ratio of total to free metal ion is illustrated and discussed. Some synthetic systems are examined to demonstrate the validity of the procedure.

New methods for determination of explosive substances as, for example, 2,4,6-trinitrotoluene (TNT), in a rapid way and at low cost are highly required. An electrochemical platform has been here developed with good characteristics of low dimension, fast response, low cost, and high selectivity. It is based on a commercially available screen printed cell with graphite ink working and auxiliary electrodes and a silver ink quasi-reference electrode. The whole cell is covered with a thick layer of cation exchanging acrylic polymer molecularly imprinted with 2,4,6-trinitrotoluene. The polymeric layer acts at the same time as electrolytic medium and selective receptor. It has been demonstrated that, in this medium, 2,4,6-trinitrotoluene is electroactive at graphite electrode, being reduced by a non-reversible reaction. The peak current (differential pulse voltammogram) is proportional to TNT concentration with limit of detection for TNT around 5 × 10(-7) M and linearity range up to 2 × 10(-5) M. The selectivity for TNT relative to other reducible compounds as, for example, nitroaromatic derivatives, and to other possible interfering substances, as negatively charged ions, is good. Measurements can be performed in not de-aerated solution and in small volumes (20 μl), so that the proposed platform is very promising for in situ determinations.

The use of solid wastes as a way to produce energy and chemicals is one of the frontiers in chemistry. One of these methods is the biomass gasification. In this thermal treatment the biomass is heated in a partially oxidising environment using different process conditions. The variability of both biomass composition and process conditions can lead the thermal treatment to several different results. In order to find a methodology for the classification of all the involved data a dataset containing biomass characterization, gasification process conditions and obtained syngas properties have been gathered from the literature. This dataset has been analysed through multivariate analysis. Principal component analysis (PCA) and a partial least square analysis (PLS) have been performed. Several correlations among different biomass and their gasification products have been found among input parameters, such as biomass properties and process conditions, and output variables like products composition and properties.

The assessment of the integrity of the DNA primary structure and the identification of canonical and modified bases are useful tools in medical, pharmaceutical, and forensic applications. In this article we report on the first microwave-assisted hydrolyses of deoxyribonucleoside-triphosphates (dNTPs) and human DNA using "Design of Experiments" methodology. We use hydrophilic interaction chromatography (HILIC) and UV detection at 260 nm for the determination of purinic and pyrimidinic bases at levels of 0.5 μM. We use a ZIC-HILIC 150mm × 2.1 mm i.d., 5 μm particle size column and ammonium formate buffers in acetonitrile for gradient separation of the analytes. We then compare the final concentrations of Thymine, Adenine, Cytosine, and Guanine with the nominal amounts of such bases in the dNTPs and DNA submitted to hydrolysis. After optimization of the hydrolysis (11.5 min, 0.15 M aqueous HCl, 150 °C), the method turns out to be suitable for the determination of products released from quantities of human DNA as low as 500 ng with precision (RSD10%) and accuracy (REC 97-104%). These results confirm that the kinetics of the release of the bases depends on their molecular structure and show that the concentration of the substrate plays a relevant role. We conclude with a discussion of the method and a comparison to the methods described in previous studies.

The sorption properties of a commercial resin containing a carboxylic active group, Amberlite® CG-50, for magnesium, calcium, copper and zinc were investigated on the basis of the Donnan model. It is assumed that the main driving force for the sorption of divalent metal ions is the complexation by the carboxylic groups inside the resin. Under typical batch conditions (large excess of ligand) only the 1:2 complexes are formed for all metal ioas considered, whereas in aqueous solution only 1:1 complexes are reported for calcium and magnesium and the monomeric analogues of the active group of Amberlite® CG-50. The intrinsic complexation constants obtained from the batch experiments agree well with those in aqueous solution. The same holds for the intrinsic complexation constant evaluated from Chromatographic experiments. This confirms some previous results obtained with a chelatteg resin containing an iminodiacetic group, Chelex 100. The values of the complexation constants for the carboxylic groups found with Chelex 100 are in agreement with those found with Amberlite® CG-50.

The sorption of metal ions on chelating resins is believed to take place through complexation by the active groups. Thus the selectivity of the resin for different metals is expected to be comparable to the complexing properties of a monomer having a structure similar to that of the active groups. This correlation can be done in a quantitative way on the basis of the Gibbs-Donnan model, which allows prediction of the extraction coefficients of metal ions on a chelating resin from the complexation constants, and other quantities, such as the concentration of the counterion in solution. In the case of chelating resins containing iminodiacetic groups, the selectivity toward some divalent metal ions is much worse than expected from the complexation by iminodiacetate in aqueous solution

Euphorbiaceae barks are known to contain an appreciable amount of polyphenolic compounds responsible for several biological activities. Preliminary extraction from Bridelia grandis stem bark afforded high content of polyphenols, determined by spectrophotometric methods such as Folin-Ciocalteu (for total phenols, TP) and n-butanol-HCl (for condensed tannins, CT). A preliminary Plackett-Burman screening design was used to identify the key factors that influence the TP and CT extraction. Between all the variables known to influence the extraction from vegetable matrixes, six were selected; maceration was chosen as traditional extraction methodology. To investigate the effect of solvents and extraction method, methanol, acetone 70% (v/v in water), centrifugation and ultrasound were chosen. A full factorial design 2(3) was applied to optimize the extraction procedure. The responses were obtained analyzing the extracts for their TP and CT contents determined by the above-mentioned spectrophotometric methods. The results confirm that, within the explored domain, the optimum solvent is methanol and the optimum method is one-cycle centrifugation. Finally, it was also compared with the effect of maceration on the considered responses. It has never given results better than centrifugation, whereas in the case of CT it represents an advantage to employ a three-cycle centrifugation instead of one.

The efficiency of the metal ion recovery by solid phase extraction (SPE) in complexing resins columns is predicted by a simple model based on two parameters reflecting the sorption equilibria and kinetics of the metal ion on the considered resin. The parameter related to the adsorption equilibria was evaluated by the Gibbs–Donnan model, and that related to the kinetics by assuming that the ion exchange is the adsorption rate determining step. The predicted parameters make it possible to evaluate the breakthrough volume of the considered metal ion, Cu(II), from different kinds of complexing resins, and at different conditions, such as acidity and ionic composition.

The sorption of a number of metal ions on the strong-base resin AG 1 × 8 containing the azo-dye Chromotrope 2B has been studied using conventional analytical methods. While lead, cadmium, zinc and magnesium are not sorbed, copper, lanthanum and nickel are. The sorption of nickel was unexpected because complexation in water is negligible. In the resin phase a 1:2 complex was found. For copper both the 1:1 and 1:2 complexes are formed depending on the ligand concentration in the resin. Evidently, the high ligand concentration in the resin promotes the formation of the 1:2 complex. For lanthanum also 1:1 and 1:2 complexes are formed. The experimentally determined extraction coefficients can be related to the intrinsic formation constants with the aid of the Donnan equilibrium. A good agreement is found for the 1:1 complexes of copper and lanthanum, but not for the 1:2 complex of lanthanum, probably due to large differences in the activity coefficients.

Different experimental approaches have been suggested in the last few decades to determine metal species in complex matrices of unknown composition as environmental waters. The methods are mainly focused on the determination of single species or groups of species. The more recent developments in trace elements speciation are reviewed focusing on methods for labile and free metal determination. Electrochemical procedures with low detection limit as anodic stripping voltammetry (ASV) and the competing ligand exchange with adsorption cathodic stripping voltammetry (CLE-AdCSV) have been widely employed in metal distribution studies in natural waters. Other electrochemical methods such as stripping chronopotentiometry and AGNES seem to be promising to evaluate the free metal concentration at the low levels of environmental samples. Separation techniques based on ion exchange (IE) and complexing resins (CR), and micro separation methods as the Donnan membrane technique (DMT), diffusive gradients in thin-film gels (DGT) and the permeation liquid membrane (PLM), are among the non-electrochemical methods largely used in this field and reviewed in the text. Under appropriate conditions such techniques make possible the evaluation of free metal ion concentration.

Introduction The aim of this study was to compare the nickel released from 3 kinds of orthodontic brackets: new conventional stainless steel, recycled stainless steel, and nickel-free brackets. Methods This in-vitro study was performed by using a classic batch procedure. Samples were immersed in artificial saliva at various acidities (pH 4.2, 6.5, 7.6) over an extended time interval (0.25, 1, 24, 48, and 120 hours). The amount of nickel released was determined by using an atomic absorption spectrophotometer and an inductively coupled plasma atomic emission spectrometer. Statistical analysis included a linear regression model for repeated measures, with calculation of Huber White robust standard errors to account for intrabracket correlation of data. For post-hoc comparisons, the Bonferroni correction was applied. Results The recycled brackets released the most nickel (74.02 ± 170.29 μg per gram); the new stainless steel brackets released 7.14 ± 20.83 μg per gram. The nickel-free brackets released the least nickel (0.03 ± 0.06 μg per gram). All the differences among the groups were statistically significant (P = 0.000). Conclusions Reconditioned brackets released the most nickel. Moreover, the highest nickel release was recorded in the 2 experiments performed at pH 4.2; it was lower at pH 6.5 and 7.6. Conversely, no relevant differences were observed overall between the maxillary and mandibular arches.

Absence of gradients and Nernstian equilibrium stripping (AGNES) is an emerging electroanalytical technique designed to measure free metal ion concentration. The practical implementation of AGNES requires a critical selection of the deposition time, which can be drastically reduced if the contribution of the complexes is properly taken into account. The resin titration (RT) is a competition method based on the sorption of metal ions on a complexing resin. The competitor here considered is the resin Chelex 100 whose sorbing properties towards Pb(II) are well known. The RT is a consolidated technique especially suitable to perform an intercomparison with AGNES, due to its independent physicochemical nature. Two different ligands for Pb(II) complexation have been analyzed here: nitrilotriacetic acid (NTA) and pyridinedicarboxylic acid (PDCA). The complex PbNTA is practically inert in the diffusion layer, so, for ordinary deposition potentials, its contribution is almost negligible; however, at potentials more negative than −0.8 V vs. Ag/AgCl the complex dissociates on the electrodic surface giving rise to a second wave in techniques such as normal pulse polarography. The complex PbPDCA is partially labile, so that its contribution can be estimated from an expression of the lability degree of the complex. These new strategies allow us to reduce the deposition time. The free Pb(II) concentrations obtained by AGNES and by RT are in full agreement for both systems here considered. The main advantage of the use of AGNES in these systems lies in the reduction of the time of the experiment, while RT can be applied to non-amalgamating elements and offers the possibility of simultaneous determinations.

The distribution of copper(II) in species of different stability in some estuarine and sea water samples (Adriatic Sea) was investigated by a method based on the sorption of the metal ion on a strongly sorbing resin, Chelex 100, whose sorbing properties have been previously characterized. From them, it is possible to predict very high values of detection windows at the considered conditions, for example side reaction coefficient as high as 10(10) at pH 7.5. Strong copper(II) species in equilibrium with Chelex 100 were detected, at concentration 2-20nM, with a reaction coefficient approximately 10(10.6) at pH 7.45 in sea water, strictly depending on the acidity. They represent 50-70% of the total metal ion and are the strongest copper(II) complexes found in sea water. Weak complexes too were detected in all the samples, with reaction coefficient lower than ca. 10(9) at the same pH. The method applied, named resin titration (RT), was described in a previous investigation, and is here modified in order to be carried out on oceanographic boat during a cruise in the Adriatic Sea.

The aluminium species in different tea infusions were investigated, by determining their stability constants and concentration. This was done for some particular samples using a simple experimental method based on the sorption of aluminium on the strongly sorbing resin Chelex 100, by a batch procedure. From the thermodynamic information obtained it is possible to calculate the concentration of the different species, and in particular that of the free metal ion, which is very important for evaluating the adsorption of aluminium on biological membranes. It was found that aluminium in the tea infusions here considered is present at high total concentration, approximately 0.1 mM, but mainly linked to strong complexes, for instance with side reaction coefficient higher than 10(5.11) at pH 3.95 in one case (tea 1). This could be the reason for the low toxicity of aluminium in tea. These strong complexes were not dissociated even in the presence of Chelex 100. In this case only a limiting value of the reaction coefficient could be evaluated. The presence of the very strong complexes was found in all the tea sample here considered. In two of the considered samples (one black and one green tea) a part of Al(III) was linked to less strong complexes, for example with a reaction coefficient 10(4.14) (tea 2, pH 4.20). The presence in the considered tea infusions of other substances able to complex aluminium was also detected, by the well known ligand titration procedure, at concentration ranging from 0.65 to 3.37 mM in three tea infusions, and at somewhat higher concentration in the case of the ready drink, which was also considered for comparison.

The synthesis and the physico-chemical characterisation of a novel solid phase, designed for iron(iii) sorption, are presented. The solid (indicated in the following as DFO-SAMMS) is made with a hydroxamate siderophore, the deferoxamine (DFO), covalently bound on a self-assembled monolayer on mesoporous silica (SAMMS). The data demonstrate that the DFO molecules are bound to the solid material, grafted on the surface and do not enter the silica pores. A new one-pot synthesis is presented in which DFO is dissolved in DMSO, and left to react with GPTMS with stirring overnight. In the same mixture, SAMMS is added to get the final product. The optimisation of experimental conditions of this novel one-pot synthesis is presented, with results indicating that a temperature of 90 °C, for the reaction between DFO and GPTMS, and the use of MCM-41 silica are the most convenient conditions. The kinetics of sorption reveals that the iron uptake is relatively fast, around 100 min at pH = 2.5, and from the sorption profile of iron(iii), the estimated capacity of the product obtained under optimized conditions was higher than 0.3 mmol g(-1). The results found in the present research are very promising for application in real biological samples.

The distribution of some metal ions in seawater samples among different species was investigated by the resin titration (RT) procedure, based on the separation of the metal ion on resins with different sorbing properties. Two complexing resins were used for the titration of four metal ions (Cu(II), Cd(II), Ni(II) and Mn(II)): Amberlite CG 50 and Chelex 100. The first one is a weak resin, able to sorb only the metal ion combined in weak complexes, or free, while Chelex 100 is a strongly sorbing resin, able to sorb also the metal ion combined in strong complexes. The concentration of the total metal ion completely sorbed and/or in equilibrium with the resin is obtained by RT. Also the reaction coefficient, i.e. the fraction of total to free metal ion in the solution phase, in the presence of the resin, can be calculated. By comparing the titration with the two resins, three groups of species for each metal ion can be detected. For each of these, the reaction coefficients are evaluated, or at least their limiting values. For example, the complexes detected with Chelex 100 in the seawater samples here examined had very high reaction coefficients: in the case of copper in one Ligurian Sea sample at pH=7.1, log α ( M(I) ) =9.7 was found, for a complex concentration corresponding to 62% of the total metal ion. The rest of Cu(II) was linked to complexes with log α(M(I)) near to 1, weak enough to be dissociated and sorbed on Amberlite CG 50. The proportion of the groups of complexes was different in the different samples examined, while the reaction coefficients were similar.

New solid-phases for the binding, separation and extraction of perrhenate and pertechnetate (ReO(4)(-) and TcO(4)(-)) from water solutions have been developed from a selective molecular receptor. Host compounds being capable of encapsulating these oxoanions are of great interest. The azacryptand, containing two tripodal tetra-amine subunits covalently linked by p-xylyl spacers, is known to display high affinity for ReO(4)(-) and TcO(4)(-) in water. The syntheses of new solid phases, obtained by fixing the receptor on mesoporous silica MCM-41 and Amberlite CG50 supports, are here described. FT-IR, micro-Raman, elemental analysis (CHN), sorption isotherms, (29)Si MAS NMR, and SEM/EDS were employed for solids characterisation. Promising performances were found for silica derivatives, for which the amount of the receptor fixed on silica ranged from 0.2 to 0.3 mmol g(-1). The perrhenate sorption mechanism was investigated with the aim to select the conditions for application in batch and fixed bed column systems.