A potentiometric determination of potassium ethyl xanthate

A potentiometric determination of potassium ethyl xantbate with Cu(II)-acetate is described From the results it follows that CS₂ reacts quantitatively with etimnolic KOH to give potassium ethyl xanthate The method may therefore be used for the determination of CS₂.     

Ion-selective electrodes in organic analysis-determination of xanthate

A PVC membrane xanthate-selective electrode has been developed for the direct determination of xanthates of primary and secondary alcohols. The xanthate electrode is highly selective and exhibits a Nernstian response in the range 5.0 x 10(-2)-7.1 x 10(-5)M xanthate with a slope of 58.6 mV per concentration decade. The electrode has a wide working pH range (5.0-11.5), a fast response time (less than 30 sec) and is stable for at least two months.     

Substoichiometric determination of zinc with potassium ethyl xanthate

A rapid radiochemical method has been designed for the determination of microgram quantities of zinc, based on the substoichiometric isotope dilution, using potassium ethyl xanthate as the extraction reagent. pH 5.5 in acetate buffers and chloroform as the extractant were found to be suitable for quantitative substoichiometric extraction. The influence of the diverse ions on the extraction was studied. The zinc contents of a medicinal preparation and biological samples were determined by the present method.     

Capillary electrophoretic determination of dithiocarbamates and ethyl xanthate

A simple and sensitive capillary electrophoretic method was developed for the separation and determination of sodium methyldithiocarbamate (metham), manganese ethylenebisdithiocarbamate (maneb) and ethyl xanthate in boric acid buffer by direct UV absorbance detection at λ = 254 nm. The separation is dependent on pH and nature of the buffer. The detection limits (S/N = 3) are 1.7 × 10^–6 mol/L for ethyl xanthate, 1.3 × 10^–6 mol/L for metham and 2.1 × 10^–6 mol/L for maneb. The method has been successfully applied to the analysis of wheat samples spiked with maneb and in a commercial sample.     

Substoichiometric determination of selenium with potassium ethyl xanthate

A substoichiometric radiochemical method has been developed for the determination of selenium with potassium ethyl xanthate. The selenium ethyl xanthate complex formed was extracted into chloroform from borate buffer at pH 5. The effect of foreign ions on the extraction was studied. Microgram quantities of selenium could be conveniently determined with a fair degree of accuracy. The method has been successfully applied for the determination of selenium content in food stuffs such as Jaggery and Wheat powder.     

Capillary electrophoretic determination of dithiocarbamates and ethyl xanthate

A simple and sensitive capillary electrophoretic method was developed for the separation and determination of sodium methyldithiocarbamate (metham), manganese ethylenebisdithiocarbamate (maneb) and ethyl xanthate in boric acid buffer by direct UV absorbance detection at lambda = 254 nm. The separation is dependent on pH and nature of the buffer. The detection limits (S/N = 3) are 1.7 x 10(-6) mol/L for ethyl xanthate, 1.3 x 10(-6) mol/L for metham and 2.1 x 10(-6) mol/L for maneb. The method has been successfully applied to the analysis of wheat samples spiked with maneb and in a commercial sample.     

Determination of the flotation collector ethyl xanthate by flow-injection analysis

A flow-injection method for determination of xanthate with amperometric detection is presented. A composite carbon electrode modified with silica gel is used for detection. Very good reproducibility (1.5% r.s.d.) results from renovation of the electrode surface by three potential scans between measurements. In the analysis of flotation liquor, the interfering effect of metal complexes, formed by leaching of the ore in water, is eliminated by addition of EDTA. The method can be used to determine ethyl xanthate in the concentration range 0.10-10.0 mg/1, with a detection limit of 0.04 mg/1.     

The influence of activated carbon on the thermal decomposition of sodium ethyl xanthate

The thermal decomposition of SEX in a nitrogen atmosphere was studied by coupled thermogravimetry-Fourier transform infrared spectroscopy (TG-FTIR), and by pyrolysis-gas chromatography-mass spectrometry (py-GC-MS). The TG curve exhibited two discrete mass losses of 45.8% and 17.8% respectively, at 200 and 257–364°C. The evolved gases identified as a result of the first mass loss were carbonyl sulfide (COS), ethanol (C₂H₅OH), ethanethiol (C₂H₅SH), carbon disulfide (CS₂), diethyl sulfide ((C₂H₅)₂S), diethyl carbonate ((C₂H₅O)₂CO), diethyl disulfide ((C₂H₅)₂S₂), and carbonothioic acid, O, S, diethyl ester ((C₂H₅S)(C₂H₅O)CO). The gases identified as a result of the second mass loss were carbonyl sulfide, ethanethiol, and carbon disulfide. Hydrogen sulfide was detected in both mass losses by py-GC-MS, but not detected by FTIR. The solid residue was sodium hydrogen sulfide (NaSH).SEX was adsorbed onto activated carbon, and heated in nitrogen. Two discrete mass losses were still observed, but in the temperature ranges 100–186°C (7.8%) and 186–279°C (11.8%). Carbonyl sulfide and carbon disulfide were now the dominant gases evolved in each of the mass losses, and the other gaseous products were relatively minor. It was demonstrated that water adsorbed on the carbon hydrolysed the xanthate to cause the first mass loss, and any unhydrolysed material decomposed to give the second mass loss.Mr. N. G. Fisher would like to thank the A. J. Parker CRC for Hydrometallurgy for the provision of a PhD scholarship.     

Substoichiometric radiochemical determination of antimony with potassium ethyl xanthate

A rapid and sensitive substoichiometric radiochemical method has been developed for the determination of microgram amounts of antimony employing potassium ethylxanthate as a reagent and chloroform as an extractant from sulfuric acid medium. The effect of associated ions on the extraction was studied. The method developed was successfully applied to determine the antimony content in standard solutions and synthetic mixture with an average error ±2.07%     

Chloroform extraction of ethyl xanthate complexes from sulphuric acid media

The chloroform extraction of 30 elements (Fe, Co, Ni, Zn, Cd, Ge, Sn, V, As, Sb, Bi, Cu, Ag, Au, Mn, Re, Ga, In, Tl, Se, Te, Cr, Mo, U, Pt, Pd, Rh, Ir, Ru and Ce) from 0.1-8M sulphuric acid in the presence of potassium ethyl xanthate has been studied. Pd(II), Bi, As(III), Sb(III), Se(IV) and Te(IV) are completely extracted and Au(III) is largely extracted over the range of acid concentration investigated. Fe(II), Tl(I), Rh(III) and Cr(VI) are only slightly extracted and Se(VI), Te(VI), Ru(III), Cr(III), Mn(II), Zn, Ce(IV), Ir(IV) and Ge(IV) are not extracted at all. Depending on the acid concentration, the remaining elements are all partly extracted. Results are compared with those obtained in an earlier study of the extraction of xanthate complexes from hydrochloric acid media. The processes involved in the formation of some xanthate complexes and potential analytical separations are discussed.     

Liquid-liquid extraction of zinc(II) as its ethyl xanthate

A method for quantitative extraction of zinc with potassium ethyl xanthate into carbon tetrachloride is described. The optimum conditions are: pH 5-6 and Zn(II) to reagent ~1:8 mole ratio. The effects of other ions on the extraction of Zn(2+) have been investigated, and its separation from As(3+), Pb(2+), Cu(2+) and Fe(3+)is described. The possibility of repeated use of the solvent (still loaded with xanthate after the zinc has been stripped) for further extractions (after addition of a little extra xanthate) has been explored. Various stripping agents have been examined, and the optimum conditions found.     

Adsorption of ethyl xanthate anions on a silver electrode. An in-situ FTIR study

The adsorption of ethyl xanthatc ion (EX⁻) on a silver electrode in sodium sulphate, phosphate buffer (pH 6.8) and borate buffer (pH 9.2) solutions was studied in situ using Fourier transform IR reflection spectroscopy. The measurements were carried out using a thin-layer flow cell, which allows a continuous supply of the electroactive species into the thin layer. The voltammetric behaviour of the silver electrode in EX⁻-containing solution is characterized by the formation of silver ethyl xanthate (AgEX), which is preceded by a prewave due to chemisorption of ethyl xanthate. An IR band at 1220 cm ⁻¹, assigned to chemisorbed ethyl xanthate, was observed in spectra obtained in the chemisorption region. All IR bands characteristic of AgEX were observed in spectra of a silver electrode surface covered by a few monolayers of AgEX. The in-situ IR measurements also showed that the adsorption of EX⁻ starts directly on the positive side of the potential of zero charge of silver (−0.7 V/SHE).     

Substoichiometric radiochemical determination of silver with potassium ethyl xanthate in photofilm washings

An accurate and rapid radiochemical method has been developed for the determination of microgram amount of silver employing potassium ethyl xanthate as a substoichiometric radiochemical reagent. The light yellow coloured silver ethyl xanthate formed was extracted into nitrobenzene from sulphuric acid media. The effect of foreign ions on the extraction was studied. The method was applied to the determination of silver content in photofilm washings.     

Utilization of potassium ethyl xanthate as a substoichiometric reagent for the determination of indium

A sensitive and rapid radiochemical method has been developed for the determination of microgram amounts of indium(III) based on the substoichiometric extraction of its 13 complex with potassium ethyl xanthate from pH 7 ammonia buffer into chloroform. 5–50 g of indium was determined with an average error of 1.56%. The effect of associated species on the extraction was studied.     

Flow injection analysis of ethyl xanthate by in-line dialysis and UV spectrophotometric detection

A simple and sensitive spectrophotometric flow method for determination of low concentrations of the flotation collector O-ethyldithiocarbonate (ethyl xanthate, CH₃CH₂-O-CS₂⁻) in solutions is described. The method is based on ethyl xanthate detection at 301 nm in medium of NaOH 50 mmol L⁻¹. By injection of 200 μL of sample, the analytical method shows linear response for the ethyl xanthate concentration from 0.5 up to 500 μmol L⁻¹. Successive injections of 4 μmol L⁻¹ ethyl xanthate (n = 23) show a coefficient of variation lower than 0.6%, denoting high repeatability. The detection limit is 0.3 μmol L⁻¹. At a flow rate of 2.0 mL min⁻¹, a frequency of 120 injections/h of ethyl xanthate can be attained. By introduction of a tangential dialysis cell in the FIA system, the manual sample filtration step with 0.22 μm filter was eliminated and the residual interference of suspended material, was completely overcome even for unfiltered sludge suspension samples, an important advantage that compensates for the frequency reduction to 25 injections/h elevation and detection limit elevation to 2 μmol L⁻¹, still outreaching for many applications. Potential applications of the method embrace the at line determination of ethyl xanthate in the ore processing industry, control of the concentration at its optimal level during the flotation process, as well as monitoring of residues in the effluents.     

Release of copper from commercial solid-state copper ion-selective electrodes

The release of copper from two commercial solid-state cupric ion-selective electrodes [Orion 94-29 Cupric Electrode (I) and Radiometer F1112 Selectrode (II)] was measured by immersion in the following media: 0.1M potassium nitrate (pH = 4.7), 0.5M sodium chloride (pH = 4.7) and 0.1M nitric acid. In the 0.1M potassium nitrate medium, the amount of copper released from both electrodes causes interference when they are used for the determination of cupric ion at the 10⁻⁷M level. In comparison with the 0.1M potassium nitrate medium, the copper release in the 0.5M sodium chloride and 0.1M nitric acid media was increased for electrode II but not for electrode I. The release of copper was not affected by removal of oxygen from the media but can be substantially lowered by coating the electrodes with a thin cation-exchange membrane (Nafion). The mechanism of copper dissolution is investigated.     

Ion-selective electrodes based on p-tert-butyl-homooxacalixarene di(ethyl)amides

The diethyl amides of p-tert-butyldihomooxacalix[4]arene (1), p-tert-butylhexahomotrioxacalix[3]arene (2) and p-tert-butylcalix[4]arene (3) were used as active materials in ion-selective membrane electrodes to check the detection of different kinds of cations (Na⁺, K⁺, Cs⁺, Mg^2 + , Ca^2 + , Mn^2 + , Cu^2 + , Zn^2 + , Cd^2 + , Pb^2 +  and tetramethylammonium cation). The electrode characteristics and selectivity coefficients were determined and compared. Optimisation of the PVC membrane composition was achieved using three different plasticisers (bis(2-ethylhexyl) adipate, o-nitrophenyl octyl ether and bis(2-butylpentyl) adipate). Amide 3 shows selectivity for Na⁺, whereas compounds 1 and 2 exhibit the highest selectivity for Pb^2 +  among all the studied cations. The X-ray crystal structure of dihomooxacalix[4]arene tetra(diethyl)amide (1) was determined, revealing it to be in the cone conformation.