Extraction into methyl isobutyl ketone of metal complexes with ammonium pyrrolidine dithiocarbamate formed in strongly acidic media

It is shown that stable metal complexes with ammonium pyrrolidine dithiocarbamate (APDC) are formed in strongly acidic (0.5–6 M) solutions and can be extracted into methyl isobutyl ketone (MIBK), although APDC is normally used for extractions from solutions at pH 2–12. Percentage extraction curves are presented for 24 elements (Ag, As, Au, Bi, Cd, Co, Cu, Fe, Ga, Ge, Hg, In, It, Ni, Os, Pb, Pd, Pt, Rh, Ru, Sb, Sn, Tl and Zn) from solutions of hydrochloric or nitric acid with and without addition of APDC. Some elements (e.g., Fe, Ga, Ge, In and Au) show identical extractions as their chloro complexes in hydrochloric acid with or without APDC. Others (e.g., Ni, Cu, Pd, As, Ag, Sb, It, Hg and Bi) are strongly extracted (K_d ? 20), from 2 M hydrochloric or nitric acid in the presence of APDC. Palladium (K_d = 8000), Sb (K_d = 10 000), and Bi (K_d = 3500) are particularly easily extracted. The potential of the extraction system was tested by extraction and quantification of palladium from the CANMET standard ore PTC-1; the mean value found was 12.55 μg g^?1 (ppm) palladium with a relative standard deviation of 7.6% (n = 12) and a relative error of 1.2% from the recommended value of 12.70 μg g^?1.     

Composite ion exchanger for removal of sodium-24 from mineralizates of biological materials in neutron activation analysis

A composite ion exchanger containing hydrated antimony pentoxide (HAP) in polystyrene-divinylbenzene matrix has been prepared. Its sorption properties with respect to Na, As, Au, Cd, Cu, Ga, Hg, In, K, La, Mn, Mo (Tc), Pd, Pt, Sb, W and Zn have been examined. Sodium is quantitatively retained on the sorbent from 8M HCl solution as well as from a mixture of conc. H₂SO₄+ conc. HNO₃+H₂O (1+1+2). As, W, Cd and Sb are partially retained, while the remaining elements are not retained and can be quantitatively eluted. The composite ion exchanger is stable to oxidizing acid media and it can be directly applied to separation of²⁴Na from mineralizates of neutron-irradiated biological materials.     

The quantitative separation of calcium from magnesium,aluminium and other elements by cation-exchange chromatography in ethanol-hydrochloric acid

Magnesium can be separated from calcium by elution with 3.0 M hydrochloric acid containing 60% ethanol from a column of AG₅₀W-X8 cation-exchange resin. Calcium is retained and can be eluted with 3.0 M hydrochloric acid or 2.0 M nitric acid. The separation factor of (α_Mg^ca=5.6 is considerably higher than that in aqueous hydrochloric acid and comparable to those obtained with organic complexing reagents. Separations are sharp and quantitative; up to 10 mmol of magnesium can be separated from 0.01 mmol of calcium and vice versa on a 60-ml column. Al, Fe(III), Mn, Ni(II), Co(II), Zn, Cd, Cu(II), Pb(II), U(VI), Be, Ga, Ti(IV) in the presence of H₂O₂ and many other elements accompany magnesium and can be separated from calcium quantitatively. Sr, Ba, Zr, Hf, Th, Sc, La and the rare earths are retained together with Ca, but can be separated by other methods.     

Oximidobenzotetronic acid as a reagent for the separation and gravimetric determination of palladium and cobalt

Oximidobenzotetronic acid is recommended for the separation and gravimetric determination of palladium and cobalt An ethanolic solution of the reagent quantitatively precipitates palladium(II) from solutions which are 0.75 N in acid up to pH 5.1, the complex is weighed as Pd(C₉H₅NO₄)₂. Cobalt(II) can be determined in the filtrate after the precipitation of palladium. With 0.5 N acid solutions, no interference was found from Pt(IV), Ir(IV), Rh(III), Ru(III), Os(IV), Au(III), Ag(I), Cu(II), Fe(III), Ni(II), Hg(II). Pb(II), Bi(III), Cd(II), As(V), Se(VI), Te(IV), Mo(VI), Sb(III), Al(III), Cr(III), Zn(II), Ti(IV), Zr(IV). acetate, oxalate, citrate, tartrate, phosphate and fluoride.     

Separation of alkaline earth elements by cation-exchange chromatography in ammonium malonate media

Be(II), Mg(II), Ca(II), Sr(II) and Ba(II) can be separated by elution from a cation-exchange column in the ammonium form with increasing concentrations of ammonium malonate. A typical elution sequence for a 60-ml column (volume in H⁺-form) of AG₅₀-X8 resin is: 200 ml of 0.20 N ammonium malonate plus 0.10 N malonic acid for Be(II); 300 ml of 0.50 N, 450 ml of 0.70 N, 350 ml of 1.10 N ammonium malonate for Mg(II), Ca(II) and Sr(II), respectively, and 200 ml of 3.0 N nitric acid for Ba(II). Separations are sharp and quantitative for element pairs in weight ratios from 1:1000 to 1000:1. Distribution coefficients, elution curves and quantitative separations are presented.     

Separation of 90Y from 90Sr using sequential multiple column extraction chromatography

The distribution coefficient measurements on Y(III) and Sr(II) were performed using ditertiarybutyl dicyclohexano 18-crown-6 (Sr-selective resin) and N,N,N′,N′-tetraoctyldiglycolamide (Y-selective resin) in HNO₃, HCl and HClO₄ media. Separation factors (⁹⁰Y/⁹⁰Sr) based on distribution coefficient data suggested that perchloric acid is distinctly better medium as compared to nitric acid/hydrochloric acid. The mechanism of extraction changes with the nature and concentration of acid and is responsible for the high selectivity in perchloric acid medium. Sequential column studies were carried out on tracers (radioactive/stable) employing Sr-selective/Y-selective extraction chromatographic resins as stationary phases. The final elution of ⁹⁰Y was done in 0.01 M EDTA at pH 4.0 which can be used for clinical applications after radiochemical processing.     

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.     

Determination of arsenic and antimony in niobium by radiochemical neutron activation—γ-spectrometry

A method for the determination of arsenic and antimony in niobium, with simultaneous determinations of Au, Cu and Mo, is described. The samples are irradiated for 12 h in a thermal neutron flux of 8 × 10¹³ n cm^-2 s^-1 and then dissolved in hydrofluoric —nitric acid. After addition of various masking agents, and reduction with potassium iodide, As(III) and Sb(III) are extracted with diethylammoniumdiethyldithiocarbamate in chloroform. Before reduction, Au, Cu and Mo can be extracted as dithiocarbamates and determined. For samples of about 100 mg, the limits of detection are 10 pg g^-1 for As, 20 pg g^-1 for Sb, 0.8 pg g^-1 for Au, 10 pg g^-1 for Cu and 25 ng g^-1 for Mo. Results are given for niobium samples of different grades of purity.     

Assessment of the sequential principal component analysis chemometric tool to identify the soluble atmospheric pollutants in rainwater

In this study a new method of principal component (PC) analysis, sequential PC analysis (SPCA), is proposed and assessed on real samples. The aim was to identify the atmospheric emission sources of soluble compounds in rainwater samples, and the sample collection was performed with an automatic sampler. Anions and cations were separated and quantified by ion chromatography, whereas trace metals and metalloids were determined by inductively coupled plasma mass spectrometry. SPCA results showed eight interfering PCs and ten significant PCs. The interfering cases originated from different atmospheric sources, such as resuspended crustal particles, marine aerosols, urban traffic and a fertilizer factory. The significant PCs explained 84.6% of the total variance; 28.1% accounted for the main contribution, which was resuspended industrial soil from a fertilizer factory containing NO₂^-, NH₄⁺, NO₃^-, SO₄^2-, F^-, Al, K⁺, Mn, Sb and Ca²⁺ as indicators of the fertilizer factory. Another important source (15.0%) was found for Na⁺, Mg²⁺, K⁺, Cl^- and SO₄^2-, which represents the marine influence from south and southwest directions. Emissions of Ba²⁺, Pb, Sr²⁺, Sb and Mo, which represent a traffic source deposited in soils, were identified as another abundant contribution (12.1%) to the rainwater composition. Other important contributions to the rainwater samples that were identified through SPCA included the following: different urban emissions (Cu, As, Cd, Zn, Mo and Co, 18.1%), emissions from vegetation (HCOO^-, 7.7%) and emissions from industrial combustion processes (Ni, V 15.6%). The application of SPCA proved to be a useful tool to identify the complete information on rainwater samples as indicators of urban air pollution in a city influenced mainly by vehicle traffic emissions and resuspended polluted soils.     

Chloroform extraction of metal ethyl xanthates from hydrochloric acid media

The chloroform extraction of 32 elements (Fe, Co, Ni, Zn, Cd, Ge, Sn, Pb, V, As, Sb, Bi, Cu, Ag, Au, Mn, Re, Ga, In, Tl, Ce, Se, Te, Cr, Mo, U, Pt, Pd, Rh, Ir, Ru and Os) from O.1-10M hydrochloric acid media in the presence of potassium ethyl xanthate has been studied. The oxidation states in which some elements react, and potential analytical separations, are discussed. Pd(II), As(III) and Se(IV) are completely extracted as ethyl xanthate complexes, Te(IV) is almost completely extracted, and Au(III) is largely extracted over the range of acid concentration investigated. Mn(II), Zn, Rh(III), Ir(IV), Ru(III), Os(IV), Cr(III), Cr(VI), Ce(III) and Ce(IV) are not extracted. Ge is partly extracted from 6-10M media as the chloro-complex. Depending on the acid concentration, the remaining elements are all partially extracted as xanthate complexes.     

The separation of palladium and platinum by ion flotation

Differences in the ion flotation properties of palladium(II) and platinum(IV) chloro complexes in aqueous solutions are used to achieve separations of these metals. The anionic chloro complex PtCl^2-₆ is floated selectively with cationic surfactants of the type, RNR'₃Br, from solutions of PdCl^2-₄ and various concentrations of hydrochloric acid. The palladium(II) does not float from solutions of ? 3.0 M HCl and the platinum(IV) floated from these solutions can be recovered free of palladium. However, the separation is incomplete as much of the platinum(IV) is also unfloated from these solutions. Quantitative separations are obtained by conversion of the palladium(II) to the cationic ammine, Pd(NH₃)₄²⁺ with aqueous ammonia prior to flotation. The anionic chloro complex of platinum(IV) is unaffected by the presence of ammonia and is floated quantitatively with the surfactant n-hexadecyltri-n-propylammonium bromide from 0.01 M ammonia solutions.     

Distribution coefficients and ion exchange behaviour of some elements with Purolite S-950 in hydrochloric acid

Equilibrium distribution coefficients, K_d, are presented for some elements in hydrochloric acid using the phosphonated polystyrene ion exchange resin Purolite S-950. A few possible separations using this resin are demonstrated by elution curves and separations of synthetic mixtures of some elements (Ru, Rh, Mo, I, Li, Te, Si, Y).     

Anion-exchange behavior of various metals in hydrazoic acid media

The adsorption characteristics for 43 metals on a strongly basic ion-exchange resin Bio-Rad AG1 were examined in 0.5 M hydrazoic acid solution. The distribution coefficients for V(IV), Fe(III), Cu(II), Zn, Se(IV), Mo(VI), Pd(II), Cd, In(III), Rc(VII), Hg(II) and U(VI), which showed very strong adsorption except for Cd, were measured as a function of hydrazoic acid concentration over the range 0.05–0.5 M. Favorable differences in the distribution coefficients allow useful two- and three-component separations such as Co(II)-Fe(III), As(III)-V(IV), Cd-Zn, Cd- Hg(II), Te(IV)-Se(IV), Th-U(VI), Mn(II)-Mo(VI)-Re(VII), to be achieved on a small column.     

Synthesis and characterization of Cu,Ni and Zn binding capability of some amino- and imidazole hydroxamic acids: Effects of substitution of side chain amino-N for imidazole-N or hydroxamic-N-H for -N-CH3 on metal complexation

Solution equilibrium studies on Cu(II)-, Ni(II)- and Zn(II)-N-Me-β-Alaninehydroxamic acid (N-Me-β-Alaha), -N-Me-α-alaninehydroxamic acid (N-Me-α-Alaha), -Imidazole-4-carbohydroxamic acid (Im-4-Cha), -N-Me-imidazole-4-carbohydroxamic acid (N-Me-Im-4-Cha) and -Imidazole-4-acetohydroxamic acid (Im-4-Aha) systems have been performed by pH-potentiometry, UV–Vis spectrophotometry, EPR, CD, ESI-MS and ¹H NMR methods. According to the results: (i) the amino-N atoms are more basic in N-Me-α-Alaha and N-Me-β-Alaha than the hydroxamate function, but the trend is just the opposite between the imidazole-N(3) and hydroxamate. (ii) The metal ion anchor is always the hydroxamate part in the amino acid derivatives, while it is always the imidazole-N(3) in the studied imidazolehydroxamic acids. (iii) The three studied N-Me derivatives do not form metallacrowns. Only hydroxamate type chelate is formed with N-Me-β-Alaha, but with N-Me-α-Alaha a new type of coordination mode (via amino-N and hydroxamate-O) also exists. N-Me-Im-4-Cha also forms a dinuclear complex, [M₂L₃], with Cu(II) and Ni(II) (but not with Zn(II)). In this complex, one of the three ligands might bridge the two metal ions (five-membered hydroxamate-(O,O) plus five-membered (N_im, O_carb) bridging bis-chelating mode), while each of the additional two ligands binds to one metal. (iv) The two studied N–H derivatives, having dissociable proton on the hydroxamic-N, are able to form metallacrown species. A pentanuclear complex, [M₅L₄H₋₄], is exclusively formed above pH 4 between Cu(II) and Im-4-Aha. Interestingly, this 12-metallacrown-4 type complex, although together with various mononuclear binding isomers, appears also with Ni(II) and Zn(II). Unfortunately, the complexes of Im-4-Cha are not soluble in water at physiological pH at all.     

Preconcentration of antimony(III) from water with thionalide loaded on glass beads with the aid of collodion

2-Mercapto-N-2-naphthylacetamide (thionalide) loaded on glass beads with the aid of collodion is used for preconcentration of microgram levels of antimony(III) from aqueous solution. Antimony is quantitatively retained on the loaded beads from 0.4–0.8 mol l^?1 hydrochloric acid solutions; equilibration is achieved within 1 min. The retention capacity of the beads is 0.2 μml Sb g^?1 at 0.6 mol l^?1 hydrochloric acid. The maximum flow rate for quantitative retention is 1.27 ml min^?1 cm^?2. Antimony retained on the column is completely eluted with 10 ml of 6.0 mol l^?1 hydrochloric acid at flow rates<1.9 ml min^?1 cm^?2.     

Spectral properties and solution behavior of gold(III) coordination compounds with water-soluble porphyrins

Gold(III) coordination compounds with three water-soluble porphyrins―5,10,15,20-tetrakis(4-sulfonatophenyl)porphyrin (H₂TSPP^4–), 5,10,15,20-tetrakis(4-N-methylpyridyl)porphyrin (H₂TMPyP⁴⁺), and 5,10,15,20-tetrakis(4-N,N,N-trimethylaminophenyl)porphyrin (H₂TTMAPP⁴⁺)―have been studied. Complex [Au(TTMAPP)]⁵⁺ has been prepared for the first time. The analysis of coordination-induced shifts of proton signals in NMR spectra and intensities of Q bands in absorption spectra indicates the high degree of bond covalence in the studied metal porphyrins and a partial transfer of electron density from porphyrin to gold ion. The cationic complexes [Au(TMPyP)]⁵⁺ and [Au(TTMAPP)]⁵⁺ in aqueous solutions has been found to exist in monomeric form, while anionic complex [Au(TSPP)]^3– undergoes dimerization upon growth of concentration and solution ionic strength. Equilibrium constant for dimerization has been calculated, the constant has been found to decrease when temperature rises. Thermodynamic parameters of dimerization process have been determined: ΔH° =–31.8 kJ/mol and ΔS° =–13.8 J/mol K.     

Neutron activation of traces in electrolytic zinc sulphate solutions : Simultaneous determination of mercury,uranium and ytterbium

A neutron activation determination of traces of mercury, uranium and ytterblum in electrolytic zinc sulphate solutions has been devised The isotope ¹⁹⁷Hg was measured by means of its 68-and 77-keV photopeaks Uranium was determined by measurements of the 106-keV photopeak of the ²³⁹Np daughter activity The 50- and 53-keV X-rays of ytterbium isotopes ¹⁹⁹Yb and ¹⁷⁵Yb were counted using a 1-mm thick Nal(Tl) wafer crystal The chemical separation was performed on anion-exchange resin. The matrix activities were eliminated in 185N hydrofluoric acid while the neptunium and ytterbium activities were desorbed with 5N hydrochloric acid Mercury was eluted from the column with 0.5 M thourea-0.005 N hydrochloric acid and precipitated as sulpinde     

Ion exchange resins in steel analysis

The metals vanadium, chromium and molybdenum may be separated from the other constituents of steel by passing an acetate buffered solution of the steel through a strongly basic onion exchanger and selectively eluting the above metals from the resin column with aqueous solutions of 0.6 N sodium hydroxide, 8 N hydrochloric acid and 1 N hydrochloric acid, respectively.     

Preconcentration and Determination of Copper(II) by Novel Solid-Phase Extraction and High-Resolution Continuum Source Flame Atomic Absorption Spectrometry

Amberlite XAD-4 modified with N-para-anisidine-3,5-di-tert-butylsalicylaldimine was investigated as a new chealting sorbent for the selective separation and preconcentration of Cu(II). The metal ion was retained by chemical sorption on the modified resin, eluted by hydrochloric acid, and determined by high-resolution continuum source flame atomic absorption spectrometry. The prepared resin was characterized for the solid-phase extraction of Cd²⁺, Co²⁺, Cr³⁺, Cu²⁺, Fe³⁺, Mn²⁺, Ni²⁺, Pb²⁺, and Zn²⁺ in a column. The influence of the pH, the mass of solid phase, eluent, flow rate, and sample volume was optimized. Using the optimum conditions, only Cu(II) showed quantitative sorption at the 95% confidence level, and the recoveries of the other metal ions were below 80%. A preconcentration factor 125 was obtained for Cu(II) with a limit of detection of 0.56?µg?L^?1. The method was used for the determination of Cu(II) in tap water, river water, tomato leaves, and fish. The relative standard deviation and the relative error were lower than 7%.     

Selective separation of indium from zinc, lead, gallium and many other elements by cation-exchange chromatography in hydrohalic acid-acetone medium

Indium can be separated from Zn, Pb(II), Ga, Ca, Be, Mg, Ti(IV), Mn(II), Fe(III), Al, U(VI), Na, Ni(II) and Co(II) by selective elution with 0.50M hydrochloric acid in 30% aqueous acetone from a column of AG50W-X8 cation-exchange resin, all the other elements being retained by the column. Lithium is included in the elements retained by the column when 0.35M hydrochloric acid in 45% aqueous acetone is used for eluting indium, but the elution of indium is slightly retarded. Ba, Sr, Zr, Hf, Th, Sc, Y, La and the lanthanides, Rb and Cs should also be retained according to their distribution coefficients. Cd, Bi(III), Au(III), Pt(IV), Pd(II), Rh(III), Mo(VI) and W(VI) can be eluted with 0.20M hydrobromic acid in 50% aqueous acetone before the elution of indium, and Ir(III), Ir(IV), As(III), As(V), Se(IV), Tl(III), Hg(II), Ge(IV), Sb(III) and Sb(V), though not investigated in detail, should accompany these elements. Relevant distribution coefficients and elution curves and results for analyses of synthetic mixtures of indium with other elements are presented.