Retention of radionuclides on metal sulphide precipitates

The retention of various radionuclides on metal sulphide precipitates has been studied. The sulphide precipitates quantitatively retained the common radionuclides. The condition for 100% retention in a thin layer is small particle size (a few μm) in the precipitate. This can be ensured by pulverization of the dried precipitate of metal sulphide. ²⁰³Hg²⁺ is retained by mercury sulphide and ⁶⁵Zn²⁺ by zinc sulphide by isotopic exchange. The retention of foreign radioactive ions can be reduced or even eliminated by counter-carrier technique in cases where the retention is not due to chemical reaction, precipitate exchange. The isotopic exchange with mercury(II) sulphide and zinc sulphide enables mercury and zinc ions to be separated rapidly and determined in the presence of a number of interfering ions.     

Separation radiochimique rapide des ions argent par reduction sur le mercure

A rapid separation .of silver on mercury is proposed in order to utilize shortlived isotopes for the determination of silver by activation. The conditions allowing quantitative reduction of silver were studied; a. kinetic study showed that after 90 sec, 97% of silver could be transferred to the mercury. The spectrometric analysis of ¹¹⁰Ag was also examined. Only metals with a redox potential greater than that of mercury form amalgams, and under the irradiation conditions these metals produce virtually no activity.     

Détermination de traces de mercure dans les systèmes biologiques par activation de neutrons

Résumé Une méthode simple et rapide de détermination de traces de mercure est présentée utilisant l'activation de neutrons. Le mercure 197 sous forme de complexe (HgCl₄ ^2–) est retenu sur une résine échangeuse d'anion qui est comptée directement. La méthode est appliquée à des milieux biologiques très divers. Les échantillons contiennent des quantités de mercure allant de 10 p. p. b. à 200 p. p. m. La déviation standard dans ces cas est de ± 10%.

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Determination of traces of mercury in biological material by neutron activation

Summary A simple and rapid technique for the trace analysis of mercury by neutron activation is presented. The activated mercury, as an HgCl₄ ^2– complex, is retained on an anion exchange resin which is counted directly. Results obtained for biological samples containing 10 p. p. b. to 200 p. p. m. are given. In this range, results had a ± 10% standard deviation.

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Zusammenfassung Ein einfaches und rasches Verfahren zur Bestimmung von Spuren Quecksilber durch Neutronenaktivierung wurde beschrieben. Das aktivierte Quecksilber wird als HgCl₄ ^2– an einem Anionenaustauscherharz adsorbiert und seine Aktivität direkt gemessen. Biologische Proben mit 10 ppb bis 200 ppm Hg wurden analysiert. In diesem Bereich betrug die Standardabweichung ± 10%.

     

Séparation de traces métalliques sur goutte de mercure; application à la préconcentration de Cu(II) et Cu(I)

A method for the rapid separation of copper(II) traces on metallic mercury is proposed. The separation is rendered possible by the reduction of Cu(II) to Cu(I) on mercury in the presence of iodide ions followed by the adsorption of the uncharged complex, Cu(I), on Hg⁰. After a minute of agitation, this adsorption is quantitative (90–100%) for initial concentrations of Cu(II) between 10^?4 to 10^?6 M and iodide cone, of 10^?2 to 10^?3 M at pH 3. The volumes of the aqueous solutions are of the order of 3–10 ml and those of the drops of mercury between 0.5–1 ml. The tests were made using the isotope ⁶⁴Cu (T _1/2 = 12.8 h).     

Determination of mercury by radiochemical displacement

2–15 g of mercury has been determined by exchange with zinc in⁶⁵Zn labelled zinc sulphide. The influence of various ions which are likely to interfere in the determination of mercury has also been studied.     

Indicator Tubes and Indicator Powders for Determining Fluoride and Chloride Ions

Noncovalent immobilization of Arsenazo I, Alizarin Red, Xylenol Orange, and diphenylcarbazone by incorporation into silicic acid xerogels and modification of silica gels was studied, and procedures for determining fluoride and chloride ions by solid-phase spectrophotometry and test methods were developed. Reactions of immobilized reagents with aluminum(III), zirconium(IV), and mercury(II) were studied. The possibility of using immobilized reagent–metal ion–halide ion systems for the determination of halide ions was assessed. Indicator powders were proposed for determining 0.5–10 mg/L fluoride ions and 1–30 mg/L chloride ions, and indicator tubes were developed for determining 20–200 mg/L chloride ions. The determination of fluoride and chloride ions is based on exchange complexation reactions proceeding in the systems immobilized Xylenol Orange–zirconium(IV) and immobilized diphenylcarbazone–mercury(II), respectively. Performance characteristics of the developed procedures were estimated. The procedures were verified by determining halide ions in Narzan mineral water.     

Voltammetric methods for determination of mercury in domestic waste and compost

A voltammetric method for the determination of mercury in domestic waste, compost produced from it and in water extracts of these samples is described. The solid samples have been digested with concentrated acids and the extracts by UV irradiation. Conditions for the voltammetric determination of mercury with a gold disc electrode in samples of very complicated composition have been worked out. To avoid the disturbing influence of copper a special potential — time program has been applied, whereas the disturbing effect of iron has been removed by complexation of Fe(III) with fluoride ions or by medium exchange. The procedure proposed suits very well for determination of mercury in the samples studied. A very low leachability of mercury from compost was found.     

On solute-mercury interactions in dilute amalgams of main group metals

The paper challenges the concept of intermetallic compound formation in dilute (mole fraction <10⁻³) amalgams of s-block metals. Although the formation of these amalgams is strongly exothermic the generated energy is much lower than the Fermi level difference between pure solutes and mercury. Thermodynamic considerations suggest that the energy of metal ions is higher in amalgams than in pure s-block metals. Repulsive interactions between the cores of these metals and mercury ions are responsible for abnormally low diffusion coefficients of alkali and alkaline earth metals in mercury. The mercurophobic character of alkali metal ions demonstrates itself in the strong adsorption of these metals on the Hg-vacuum interface, and in the high rates of ion exchange between electrolytic solutions and amalgams.     

Etude de la séparation de traces de mercure ionique par adsorption,en milieu aqueux,sur verre sodocalcique. Application à la séparation Hg2+-organomercuriels

The separation conditions of traces of ionic mercury from aqueous solution on microbeads of soda lime are studied theoretically and established experimentally. The formation of a stable complex of the ion with ethylene diamine allows to operate at pH 7–8. The efficiency of the exchange is close to 96%. The methods allows the separation and essay of ionic mercury in presence of various organomercuric compounds.     

Electrochemical growth of single mercury droplets under joint ohmic, diffusion, and charge transfer limitations

Growth kinetics of single mercury droplets electrochemically deposited on a platinum single crystal electrode was investigated. Potentiostatic current transients were recorded at different electrode potentials. The experimental data were interpreted on the basis of a general theoretical model accounting for joint ohmic, diffusion and charge transfer limitations. Information is obtained on two important growth parameters: the exchange current density at the mercury/solution interface boundary and the diffusion coefficient of mercury ions. Published in Russian in Elektrokhimiya, 2006, Vol. 42, No. 6, pp. 756–759. The text was submitted by the authors in English.     

Preparation and properties of a new chelating resin containing imidazolyl azo groups

 A new chelating resin incorporating imidazolyl azo groups into a matrix of polystyrene divinylbenzene has been prepared. The exchange capacity of the resin for the ions mercury(II), silver(I) and lead(II) as a function of pH has been determined. The resin exhibits no affinity to alkali, or alkaline earth metals. It is highly selective for only mercury(II) and silver(I). In column operation it has been observed that mercury(II) in trace quantities is very effectively removed from river water spiked with mercury(II) at the usual pH of natural waters. Received: 2 January 1996/Revised: 11 April 1996/Accepted: 16 April 1996     

Influence of the interaction between adsorbed organic ions and supporting electrolyte ions on the kinetic current of protonation reaction

The paper presents an ionite model of a mercury electrode covered with adsorbed organic ions, and points out that the kinetic current of protonation in the presence of ionic surfactants depends on the process of ion exchange with the participation of the so-called ionite layer formed during the adsorption of organic ions, which have long carbon chains (C10).     

Composés de solvatation des halogenures de mercure II avec quelques amines aliphatiques

Addition compounds of anhydrous mercury(II) halides were prepared with propylamine, isopropylamine, butylamine and isobutylamine. These solyates have the general formula HgX₂, 2RNH₂. A study of their thermal stability by TG and DTA methods has shown that some stable intermediates are produced in the course of decomposition. The standard enthalpies of formation have been determined by dissolution in acidic medium and the variation of enthalpy based on the evolution of the molecules of amine was determined by this way and by means of a differential enthalpic analyser. The interpretation of their infrared spectra is discussed.     

Spectrophotometric determination of microamounts of mercury(II) and sulfide ions in aqueous solution

Ammonium (2′,3′-dihydroxy pyridyl-4′-azo)benzene-4-arsonate (DHP-4A) provides a simple, rapid, and sensitive spectrophotometric microdetermination of mercury(II) in aqueous solution. The magenta colored 1:2 metal to ligand complex formed has a molecular extinction coefficient 6.25 × 10⁴ liters mol^?1 cm^?1 at the maximum absorption of 535 nm in highly alkaline medium. Beer's law is obeyed up to 3.8 ppm and Sandell's sensitivity (for an absorbance of 0.001) is 0.0032 μg of mercury(II)/cm². The mercury(II) complexed with DHP-4A has also been used in microdetermination of sulfide ions using ligand exchange reaction. The optimum concentration range of sulfide ions which can reproducibly be determined is 0.16-5.05 μg/10 ml and sensitivity of sulfide ions determination (for an absorbance 0.001) is 7.3 × 10^?4 μg/cm².     

Schnelle isotopische Trennungsmethode zum selektiven Nachweis von kurzlebigen Radioisotopen

Zusammenfassung Es wird ein neues radiochemisches Trennverfahren beschrieben, in welchem metallisches Quecksilber oder dessen verdünnte Amalgame als Extraktionsmittel fungieren. Dabei unterscheidet man einen isotopischen und einen redoxierenden Austausch, je nachdem die ausgetauschten Partikel chemisch gleich oder verschieden sind. Auf Grund elektro-kinetischer und metallurgischer Überlegungen wird der Anwendungsbereich der Methode abgegrenzt.Die Kinetik und der Einfluß des chemischen Milieus auf den Isotopenaustausch von Hg ₂ ²⁺ - und Hg²⁺-Ionen und den redoxierenden Austausch von Ag⁺-, Au³⁺- und Pt⁴⁺-Ionen gegen reines Quecksilber werden im einzelnen untersucht. In Gegenwart eines ionischen Austauschträgers wird selbst organisch gebundenes Quecksilber in weniger als 3 min quantitativ ausgetauscht. Der Einfluß von Komplexbildungskonstanten auf das Austauschgleichgewicht wird für Silberionen demonstriert. Der Austausch, der in saurem oder neutralem Milieu bei ca. 80% ein Gleichgewicht erreicht, wird in Gegenwart eines Ammoniakpuffers quantitativ. Es wird ferner gezeigt, wie aus dem gleichen Grund in Gegenwart von Cyanidionen der Austausch für Quecksilberionen hochselektiv wird.Als erste Anwendung der Methode wird die Bestimmung von 0,09 ppm Gold in Pyritproben (Bestrahlung 30 min bei 10¹³ n · cm^–2 · sec^–1) beschrieben.

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Summary A new method of radiochemical separation is proposed in which metallic mercury or its diluted amalgams are employed as extraction agents. The method is denoted by isotopic exchange when the particles exchanged are of the same chemical nature, or by redox exchange, when the separation is controlled by redox phenomena. By means of electrokinetic and metallurgical considerations the field of application of this method has been demarcated.Kinetics and influence of medium in the isotopic exchange of mercury ions, and in the redox exchange of silver, gold, and platinum ions with mercury of high purity were examined. Even in labelled organic compounds covalently bound mercury is exchanged in less than 3 min when a ionic exchange scavenger is added. The influence of complex formation constants on the exchange equilibrium has been demonstrated for the case of silver ions. It will be quantitative only in presence of an ammonia buffer. Furthermore, it could be shown, that for the same reason the exchange will be highly selective for mercury ions in the presence of cyanide ions.The determination of 0.09 ppm of gold in pyrite samples (irradiation: 30 min at 10¹³ n · cm^–2 · sec^–1) has been mentioned as a first application of the new separation method.

     

A Hg(II)-specific probe for imaging application in living systems and quantitative analysis in environmental/food samples

Mercury ions are highly toxic and can accumulate along food chains in water, soil, crops and animals. Effective detection of mercury ions in various media is of great significance for maintaining the ecological environment and protecting people’s health. In this work, a mercury ions specific fluorescent probe was developed by a simple one-step reaction of commercial substrates of 4-chloro-7-nitro-2,1,3-benzoxadiazole and 1-(2-aminoethyl)-4-methylpiperazine. Investigation on sensing behavior showed that this probe had high sensitivity and selectivity towards mercury ions. Furthermore, this probe could be used as a tool to track the level of mercury ions in living system. In living cells, the probe with green emission emitted a bright red fluorescence when it was bound to mercury ions. In Arabidopsis thaliana, similar red emission could be detected from the root tip and stalk when A. thaliana was grown in culture medium containing mercury ions. The imaging in zebrafish showed that mercury ions were mainly concentrated in the stomach and head of zebrafish. Especially, this probe could be applied in quantitative analysis of mercury ions in tap water, green tea, sea shrimp and soil. This work provided a practical tool for the detection of mercury ions in living systems and quantitative analysis in real samples.     

Microdetermination of mercury using silver and copper ion selective electrodes with silver-dithiooxamide and copper-diethyldithiocarbamate loaded polyurethane foams

Summary Microdetermination of Mercury Using Silver and Copper Ion Selective Electrodes with Silver-Dithiooxamide and Copper-Diethyldithiocarbamate Loaded Polyurethane Foams Low levels of mercury(II) are determined by passing their aqueous solutions at pH 1–3 through a column containing silver-dithiooxamide or copper-diethyldithiocarbamate loaded polyurethane foam, followed by monitoring the silver(I) and copper(II) ions released in the effluent with the solid state silver and copper ion selective electrodes, respectively. The rate of the exchange reactions is fast (<3 min) and the efficiency of displacing silver(I) and copper(II) ions is high (>98%). The calibration plots show slopes of 59 and 29 mV/concentration decade of mercury on using the silver and copper sensors, respectively. Determination of 20 ng/ml to 200/ml of mercury(II) in aqueous solutions shows an average recovery of 98.4% and a mean standard deviation of 2%. Many cations and anions do not interfere. Some organomercury compounds are similarly determined after a prior decomposition in an oxygen-filled flask. Results with an average recovery of 98.4% (mean standard deviation 1.9%) are obtained with 10 structurally different mercury compounds.     

A colorimetric and fluorescent chemosensor for detection of Hg2+ using counterion exchange of cationic polydiacetylene

In this study, a colorimetric and fluorescent chemosensor for mercury ions (Hg²⁺) was developed. Cationic polydiacetylene (PDA) vesicles with a quaternary ammonium cation and iodide as a counterion show a blue-to-red color transition; the color change is accompanied by a fluorescence enhancement in selective response to Hg²⁺ ions because of a perturbation of the ene–yne conjugated backbone induced by counterion exchange. It allows for selective detection of Hg²⁺ with the naked eye and the sensor is used to determine Hg²⁺ concentrations in tap water samples.     

Separations radiochimiques rapides par echange sur le mercure : Échange redox de l'or et du platine et dosage très sélectif de ces éléments par activation aux neutrons thermiques

A rapid extraction method of platinum and gold ions by means of a mercury drop is proposed. This is based on the different redox potentials of the various couples present and gives a separation from most other elements. The phenomenon is rapid and quantitative between defined concentration limits. The selectivity is good; silver interferes but this can be avoided. The sensitivity is excellent; with neutron activation in a flux of 7.7·10¹² n.cm^-2.sec^-1 for 2 h, the lower limit is about 5 ng/ml.     

Determination of mercury ions on a diphenylcarbazone bulk modified graphite electrode

A bulk modified electrode prepared by pressing a mixture of carbon powder and diphenylcarbazone at 15.2 MPa was used for the determination of mercury in aqueous solutions. Mercury(II) ions are concentrated by complexation with the modifier in acidic (HNO₃) solution. After exchange of the medium for 1 M HCl and 1 M CaCl₂, mercury is reduced at ?0.8 V vs. SCE. The signal is generated by anodic stripping in the differential-pulse mode. The calibration graph is linear in the range 5×10^?8?5× 10^?6 M with a relative standard deviation of 7%. After enrichment for 10 min the detection limit is 5×10^?8 M. Silver, chromate and strong complexing agents interfere. The use of the electrode to determine the labile fraction in mercury speciation is discussed.