Spectrophotometric determination of thallium after its extraction as an ion-pair of the chloro-complex and pyronine G

A sensitive and selective procedure for the spectrophotometric determination of thallium is described. The method is based on the formation of an ion-pair between [TlCl(4)](-) and the pyronine G cation in chloride-containing acid media. The ion-pair is extracted into benzene and permits the determination of as low as 0.3 mug of thallium in a final volume of 25 ml at 530 nm. The system obeys Beer's law in the concentration range 1-14 mug of thallium in a final volume of 25 ml. Potassium iodate was found to be highly effective for the oxidation of Tl(I) to Tl(III) and the presence of excess oxidant does not interfere. The method can be used for the determination of thallium in high purity cadmium, cadmium sponge and rock samples.     

Triton X-100存在下镉试剂分光光度法测定痕量铊(III)

本文首次提出了在Triton X-100存在下, 以镉试剂作显色剂于水相直接分光光度法测定了痕量铊, 结果表明: 该体系具有很高的灵敏度, 是目前分光光度法测定铊的最灵敏方法之一.     

Indirect determination of thallium by differential-pulse polarography

The method is based on the separation of Tl(I) as Tl(2)HPMo(12)O(40), stripping of the molybdate, and measurement of the peak current in differential-pulse polarography of the molybdenum. The calibration graph is linear over the range 2-12 ppm of thallium. The relative standard deviation is 1.2% (7 replicates each containing 500 microg of thallium). The current due to reduction of the molybdenum is three times that for reduction of the equivalent amount of Tl(I) in the thallous phosphomolybdate precipitate, making the indirect approach more sensitive than direct polarographic determination of the Tl(I).     

Indirect Speciation Analysis of Thallium in Plant Extracts by Anodic Stripping Voltammetry

A sensitive voltammetric method (DPASV) was developed for the determination of Tl(I) and Tl(III) in plant extracts. To limit the influence of the organic matrix on the measurements, UV irradiation and addition of Amberlite XAD‐7 resin was studied. The application of 0.5 g of the resin allowed defining thallium speciation in 10.0 mL of a solution containing 0.20 mL of Sinapis alba extract. The quantification limit of 0.5 ng mL^?1 Tl(I) was found for only 10 min of preconcentration, and is low enough to allow dilution of the sample before thallium determination. The procedure was validated using the recovery study and intermethod comparison with HPLC ICP MS.     

Radiometric trace analysis of lead with diethyldithiocarbamate and 204T1

Two methods for the determination of submugram amounts of lead are described. (A) Lead is selectively extracted with carbon tetrachloride from an alkaline solution containing exccss diethyl-dithiocarbamatc (DDC) and cyanide. Traces of DDC arc back-extracted. The lead in the DDC complex is exchanged with ²⁰⁴Tl and the amount of ²⁰⁴Tl in the organic layer acts as a measure for the lead. The limit of sensitivity is 0.1 mg; the standard deviation is 11% (for 0. 1μg). Bismuth and thallium interfere; their influence can be accounted for with the help of EDTA, however. (B) Excess cyanide is added to the alkaline sample solution and lead is exchanged selectively with ²⁰⁴Tl by shaking with a CHCl₃ solution containing ²⁰⁴T1(DDC)₁. As the process is not 100% effective (with a reasonable excess of the thallium complex) isotope dilution with ²¹⁰Pb is also carried out. The amount of ²⁰⁴Tl in the aqueous layer acts as a measure for the exchanged lead. The limit of sensitivity is 0.05 μg and the standard deviation is 12% (for 0.05 μg). Bismuth and thallium must be removed in advance, e.g. by anion exchange.     

Thallium(I) Tropolonates: Synthesis,Structure, Spectral Characteristics,and Antimicrobial Activity Compared to Lead(II) and Bismuth(III) Analogues

Synthesis, single-crystal X-ray determination diffraction and FT-IR, NMR (¹H, ¹³C, ¹⁹F and ²⁰⁵Tl), UV–vis, and luminescence spectra characteristics were described for series of thallium(I) compounds: thallium(I) triflate (Tl(OTf)), 1:1 co-crystals of thallium(I) triflate and tropolone (Htrop), Tl(OTf)·Htrop, as well as simple thallium(I) chelates: Tl(trop) (1), Tl(5-metrop) (2), Tl(hino) (3), with Htrop, 5-methyltropolone (5-meHtrop), 4-isopropyltropolone (hinokitiol, Hhino), respectively, and additionally more complex {Tl@[Tl(hino)]₆}(OTf) (4) compound. Comparison of their antimicrobial activity with selected lead(II) and bismuth(III) analogs and free ligands showed that only bismuth(III) complexes demonstrated significant antimicrobial activity, from two- to fivefold larger than the free ligands.     

Speciation analysis of thallium using electrothermal AAS following on-line pre-concentration in a microcolumn filled with multiwalled carbon nanotubes

The enrichment ability of carbon nanotubes (CNTs) was investigated and a new method established for the determination of trace thallium species in environmental samples using electrothermal atomization-atomic absorption spectrometry (ETAAS). The CNTs were employed as sorbent substrate in a continuous flow system coupled to ETAAS. Parameters influencing the recoveries of thallium were optimized. Under optimal conditions, the detection limit and precision of the method were 0.009 µg L^?1 and 3.9%, respectively. The method was applied to the determination of thallium in real environmental samples and the recoveries were in the range from 96 to 100%. This system was able to separate thallium (I) from the matrix, which allowed its selective determination. The total thallium content was then determined by reducing Tl(III) with hydroxylamine. All these experimental results indicated that this new procedure can be applied to the determination of trace thallium in drinking water samples.     

A novel tetrachlorothallate (III)-PVC membrane sensor for the potentiometric determination of thallium (III)

A novel tetrachlorothallate (III) (TCT)-selective membrane sensor consisting of tetrachlorothallate (III)-2,3,5-triphenyl-2-H-tetrazolium ion pair dispersed in a PVC matrix plasticized with dioctylphthalate is described. The electrode shows a stable, near-Nernstian response for 1×10⁻³-4×10⁻⁶ M thallium (III) at 25 °C with an anionic slope of 56.5±0.5 over the pH range 3-6. The lower detection limit and the response time are 2×10⁻⁶ M and 30-60 s, respectively. Selectivity coefficients for Tl(III) relative to a number of interfering substances were investigated. There is negligible interference from many cations and anions; however, iodide and bromide are significantly interfere. The determination of 0.5-200 μg ml⁻¹ of Tl(III) in aqueous solutions shows an average recovery of 99.0% and a mean relative standard deviation of 1.4% at 50.0 μg ml⁻¹. The direct determination of Tl(III) in spiked wastewater gave results that compare favorably with those obtained by the atomic absorption spectrometric method. The electrode was successfully applied for the determination of thallium in zinc concentrate. Also the tetrachlorothallate electrode has been utilized as an end point indicator electrode for the determination of thallium using potentiometric titration.     

Hochselektive spektralphotometrische Bestimmung von Thallium mit Natriumdi?thyldithiocarbamidat

Zusammenfassung Bei der Bestimmung des Tl(III) mit Natriumdiäthyldithiocarbamidat konnte durch Überführung des mit Tetrachlorkohlenstoff extrahierten Thalliumdiäthyldithiocarbamidat-Komplexes in den Kupferdiäthyldithiocarbamidat-Komplex eine etwa 20 fache Verbesserung der Empfindlichkeit erreicht werden. Es wurde eine Vorschrift ausgearbeitet, welche die spezifische Bestimmung des Tl in vielen Materialien erlaubt. Von 60 untersuchten Kationen und 13 Anionen stört nur Bi.

---

Highly selective spectrophotometric determination of thallium by sodium diethyldithiocarbamate

The spectrophotometric determination of thallium as Tl(III)-diethyldithiocarbamate can be improved substantially by transformation of the Tl-complex (extracted in CCl₄) into the Cu-complex. By this modification the sensitivity of the method is enhanced by a factor of about 20. A procedure has been worked out, which allows the specific determination of Tl in many materials. Of 60 cations and 13 anions tested only Bi interferes with the Tl determination.

---

---

Für die Überprüfüng des Manuskriptes bin ich Herrn Dr. P. Baertschi zu Dank verpflichtet.     

Determination of indium and thallium by hydride generation and atomic-absorption spectrometry

Hydride generation coupled with atomic-absorption spectrometry was applied to the determination of indium and thallium. The hydrides were generated in 1M HCl (In) and 1-1.5M HCl or HNO(3) (Tl) with 1% NaBH(4) solution, and were flushed with argon into an electrically heated silica tube. The characteristic mass for indium and thallium were 0.13 and 0.12 mug, respectively.     

Determination of thallium in bismuth by differential pulse anodic-stripping voltammetry without preliminary separation

The determination of trace levels of thallium in bismuth and bismuth salts by differential pulse anodic-stripping voltammetry has been made possible by using a surfactant as an electrochemical masking agent, in addition to a complexing agent. In 0.2M EDTA at pH 4.5 as supporting electrolyte in the absence of surfactant, bismuth at concentrations below 10(-4)M does not interfere. When the electrolyte also contains tetrabutylammonium ions at 0.01 M concentration, bismuth can be tolerated at concentrations up 0.05M, and the height of the thallium peak is unaffected. It is thus possible to determine 1 nM Tl(I) in the presence of 0.05M Bi(III), i.e., Tl at the 1 x 10(-6)% level in bismuth. The precision of the determination and the recovery are satisfactory. Neither an 800-fold ratio of Cu(II) nor a 10(7)-fold ratio of Pb(II) to Tl(I) interferes in the determination. Other cations such as Zn(2+), Cd(2+), In(3+), Hg(2+), Fe(3+), Sb(3+) and Sn(4+) in 10(4)-fold molar ratio to Tl(I) have no effect on the determination. Thallium has been determined in bismuth metal and in bismuth nitrate of various degrees of purity.     

Extraction-fluorimetric determination of microgram amounts of thallium with 2-phenylbenzo[8,9]quinolizino[4,5,6,7-fed]phenanthridinylium perchlorate

In 0.5 M hydrochloric acid medium, thallium(III) forms with 2-phenylbenzo [8,9]quinolizino[4,5,6,7-fed]phenanthridinylium perchlorate (PQPP) an ion-association compound which is extractable in isoamyl acetate. The extracted ion-pair has a mole ratio Tl/PQPP in 1:1 and has been used for the spectrofluorimetric determination of thallium in the concentration range 0.06–1.6 μg per 5 ml of organic layer. The interference of a large number of foreign ions has been investigated. The method is sensitive, accurate, precise, and specially useful for the determination of thallium in different materials with low contents of this element.     

Speciation Analysis of Thallium by Reversed‐phase Liquid Chromatography ‐ Inductively Coupled Plasma Mass Spectrometry

An inductively coupled plasma mass spectrometer (ICP‐MS) was used as a liquid chromatographic detector for the speciation analysis of thallium in environmental samples. In this study, ionic thallium species, namely Tl(I) and Tl(III) were well separated by reversed‐phase high performance liquid chromatography (RP‐HPLC) with a C8‐HPLC column as the stationary phase and 1 mmol L^?1 tetrabutylammonium phosphate (TBAP), 2 mmol L^?1 diethylenetriamine pentaacetic acid (DTPA) in 1% v/v methanol solution (pH 6) as the mobile phase. Effluent from the HPLC column was delivered to the nebulizer of the ICP‐MS for the determination of thallium. The separation was complete in less than 3 min. Detection limit was 0.002 μg L^?1 for both Tl(I) and Tl(III) compounds based on peak height. The relative standard deviation of the peak areas for five injections of a mixture containing 1 μg Tl L^?1 was better than 3.4%. The concentrations of Tl compounds were determined in standard reference materials, including NIST SRM 1643e Trace Elements in Water and NRCC NASS‐5 Open Ocean Seawater and water samples collected in Kaohsiung area, Taiwan. The HPLC‐ICP‐MS results of the reference samples agreed with the reference values. This method has also been applied to determine Tl(I) and Tl(III) compounds in custard apple (Annona squamosa) leaves collected from Chai‐shan Mountain, Kaohsiung and Taitung City, Taiwan. The thallium species were quantitatively leached from the leaves with a 5 mmol L^?1 DTPA in 100 mmol L^?1 ammonium acetate solution in an ultrasonic bath during a period of 30 min. The HPLC‐ICP‐MS result that was obtained after the analysis of leaves sample showed a satisfactory agreement with the total thallium concentration obtained by ICP‐MS analysis of completely dissolved sample.     

Iron(II) titration of some metal ions, with oxazine dyes as redox indicators

The use of oxazine dyes as redox indicators in the determination of uranium(VI), copper(II), osmium(VIII), iridium(IV) and thallium(III) with iron(II) as reductimetric titrant in phosphoric acid medium has been investigated. The determination of copper in brass and the analysis of the binary mixtures of U(VI) and U(IV), and of Tl(III) and Tl(I) with this reductant and these indicators have been studied.     

Anodic stripping voltammetric determination of thallium as [TlBr4]-rhodamine B complex

The anodic stripping voltammetric behaviour of the [TlBr₄]-rhodamine B complex is described and compared with that of thallium(I) and thallium(III) ions. The electrolyte composition, the best potential for the deposition of thallium from the complex in the selected electrolyte, the duration of the electrolysis, and the possibility of reduction of thallium in the [TlBr₄]-rhodamine B complex before the electrolysis with ascorbic acid were investigated. The results showed good reproducibility of the measurements of thallium as [TlBr₄]-rhodamine B complex and are similar to those obtained for thallium as Tl(I) and Tl(III) ions. As the [TlBr₄]-rhodamine B complex is strongly adsorbed on polyethylene, a previous preconcentration step on a column, packed with polyethylene powder, allowed the voltammetric determination of thallium as [TlBr₄]-rhodamine B complex in samples of KCl and NaCl as solid salts after the separation of the matrix. With this procedure it was possible to reach enrichment factors of 25 with recoveries from 96.7 to 107.9% for thallium concentrations from 5 to 40 μg L^–1 and RSD between 4.2 and 9.2%. The procedure was used to determine thallium traces in KCl and in sea salt. The results of these determinations were compared with the results obtained by graphite furnace atomic absorption spectrometry.     

泡沫塑料富集–石墨炉原子吸收光谱法测定贝类水产品中痕量铊

采取微波消解的前处理手段消解样品,经泡沫塑料分离富集后,用石墨炉原子吸收光谱法测定贝类水产品中痕量铊。以1.5 mL Fe3+,2 mL H2O2和5%王水介质作为吸附体系将样品中铊分离富集,再以硝酸钯、抗坏血酸作为基体改进剂进行测定。铊的质量浓度在0～50μg/L范围内线性良好,相关系数为0.999 7,方法的检出限可达0.07μg/g。测定结果的相对别准偏差为1.53%～4.01%(n=7),加标回收率为87.1%～98.3%。泡沫塑料富集–石墨炉子吸收光谱法测定贝类水产品中痕量铊是一种准确、安全、便捷的检测方法。     

A mercury-free electrochemical sensor for the determination of thallium(I) based on the rotating-disc bismuth film electrode

A bismuth film electrode was tested and proposed as an environmentally friendly sensor for the determination of trace levels of Tl(I) in non-deoxygenated solutions. Determination of thallium was made by anodic stripping voltammetry at a rotating-disc bismuth film electrode plated in situ, using acetate buffer as the supporting electrolyte. The stripping step was carried out by a square wave potential-time excitation signal. A univariate optimisation study was performed with several experimental parameters as variables. Under the selected optimised conditions, a linear calibration plot was obtained in the submicromolar concentration range, allowing the electrochemical determination of thallium in trace amounts; the calculated detection limit was 10.8 nM and the relative standard deviation for 15 measurements of 0.1 μM Tl(I) was ±0.2%, for a 120 s accumulation time. Interference of other metals on the response of Tl(I) was investigated. Application to real environmental samples was tested. The bismuth film electrode appears to be a promising tool for electroanalytical purposes, ensuring the use of clean methodology.     

Effects of some surface-active substances on polarographic waves of thallium(I), lead(II), antimony(III) and uranium(VI) in acetate medium: Determination of Thallium with Electrochemical Masking by Dioctyl Sulphosuccinate

The effects of some surface-active substances on the polarographic waves of Tl(I), Pb(II), Sb(III) and U(VI) in an acetate medium are described. The shifts observed in half-wave potentials offer several possibilities for the selective polarographic determination of these species. A method for the determination of thallium(I) in the presence of large amounts of Sb(III) and U(VI) and commensurate amounts of Pb(II). with dioctyl sulpho-succinate, is proposed.     

6-phenyl-2,3-dihydro-assym-triazine-3-thione and 5,6-diphenyl-2,3- dihydro-asym-triazine-3-thione as gravimetric reagents for the determination of thallium and palladium

The analytical use of 6-phenyl-2,3-dihydro-asym-triazine-3-thione (PDTT) and 5,6-diphenyl-2,3-dihydro-asym-triazine-3-thione (DDTT) has been investigated. PDTT proved to be suitable for the determination of thallium(I) in the presence of cyanide whereas DDTT is more selective than PDTT in alkaline tartrate solution and is applied for the selective gravimetric determination of palladium. The method is more sensitive than the dimethylglyoxime method. The only metal ions interfering are Hg(II), Ag and Tl(I).     

Solubility, complex formation, and redox reactions in the Tl2O3-HCN/CN(-)-H2O system. Crystal structures of the cyano compounds Tl(CN)3.H2O, Na[Tl(CN)4].3H2O, K[Tl(CN)4], and Tl(I)[Tl(III)(CN)4] and of Tl(I)2C2O4

Thallium(III) oxide can be dissolved in water in the presence of strongly complexing cyanide ions. Tl(III) is leached from its oxide both by aqueous solutions of hydrogen cyanide and by alkali-metal cyanides. The dominating cyano complex of thallium(III) obtained by dissolution of Tl2O3 in HCN is [Tl(CN)3(aq)] as shown by 205Tl NMR. The Tl(CN)3 species has been selectively extracted into diethyl ether from aqueous solution with the ratio CN-/Tl(III) = 3. When aqueous solutions of the MCN (M = Na+, K+) salts are used to dissolve thallium(III) oxide, the equilibrium in liquid phase is fully shifted to the [Tl(CN)4]- complex. The Tl(CN)3 and Tl(CN)4- species have for the first time been synthesized in the solid state as Tl(CN)3.H2O (1), M[Tl(CN)4] (M = Tl (2) and K (3)), and Na[Tl(CN)4].3H2O (4) salts, and their structures have been determined by single-crystal X-ray diffraction. In the crystal structure of 1, the thallium(III) ion has a trigonal bipyramidal coordination with three cyanide ions in the equatorial plane, while an oxygen atom of the water molecule and a nitrogen atom from a cyanide ligand, attached to a neighboring thallium complex, form a linear O-Tl-N fragment. In the three compounds of the tetracyano-thallium(III) complex, 2-4, the [Tl(CN)4]- unit has a distorted tetrahedral geometry. Along with the acidic leaching (enhanced by Tl(III)-CN- complex formation), an effective reductive dissolution of the thallium(III) oxide can also take place in the Tl2O3-HCN-H2O system yielding thallium(I), while hydrogen cyanide is oxidized to cyanogen. The latter is hydrolyzed in aqueous solution giving rise to a number of products including (CONH2)2, NCO-, and NH4+ detected by 14N NMR. The crystalline compounds, Tl(I)[Tl(III)(CN)4], Tl(I)2C2O4, and (CONH2)2, have been obtained as products of the redox reactions in the system.