Determination of trace elements in manganese metal and compounds by ion-exchange chromatography and atomic absorption spectrometry : Part 1. Determination of Li,Na, K,Be, Ti(IV), Mg,Ni, Ca and Al

Traces of the specified elements can be separated from 1-g amounts of manganese(II), using a 20-g column of AG50W-X8 cation-exchange resin. The trace elements are separated into four groups and are determined by atomic absorption spectrometry, except titanium, which is determined spectrophotometrically. With the exception of sodium, recoveries for 10 μg amounts vary between 94% (for nickel) and 101% (for magnesium). Relevant elution curves, results for the analysis of synthetic mixtures and for the determination of eight trace elements in samples of manganese metal, manganese chloride and manganese dioxide are presented.     

Quantitative separation of calcium from magnesium,aluminium, iron(III) and many other elements by cation-exchange chromatography in methanolic hydrochloric acid on a macroporous resin

Calcium can be separated from Mg, Al, Cu(II), Fe(III), Ga, Zn, Mn(II), Co(II), U(VI) and Ti(IV) by cation-exchange chromatography on a column of AG MP-50 macroporous resin. Sr, Ba, Sc, Y, the lanthanides, Zr, Hf and Th are retained together with calcium. The separation factor for the Ca—Mg pair in 3 M HCl containing 50% methanol is about 20 which is considerably larger than those obtained by other ion-exchange procedures. Separations with the cation-exchange resin are sharp and quantitative. A column containing only 2 g (5.4ml) of resin is sufficient to separate up to 0.2 mmol of calcium from 2 mmol of magnesium and larger amounts of Fe(III), Cu(II) and Zn. On a 10-g column, up to 2.5 mmol of calcium can be separated easily from similar and larger amounts of other elements. Distribution coefficients for calcium and magnesium with variation of cross-linkage and variation of methanol concentration are presented, together with relevant elution curves and results for synthetic mixtures.     

Quantitative separation of traces of lead,cadmium and many other elements from gram amounts of thallium by cation-exchange chromatography

Traces of lead and minor amounts up to 20 mg, can be separated from gram amounts of thallium by cation-exchange chromatography on a column containing only 2 g of AG50W-X4 resin. Thallium passes through the column in 0.1 M HCl in 40% acetone. The retained lead can be eluted with 3 M HCl or HNO₃. Other elements, including Cd, Zn, In, Ga, Cu(II), Fe(III). Mn(II), Co(II). Ni(II), U(VI) and Al, are retained quantitatively with lead. Only Hg(II), Au(III), the platinum metals, bismuth and elements forming oxyanions accompanying thallium. Results for the determination of trace elements in 99.999% pure thallium are presented.     

Separation of silver from zinc, cadmium, copper, nickel and other elements in nitric acid with a macroporous resin

Traces of silver and amounts up to 50 mg can be separated from up to gram amounts of Zn, Cu(II), Ni, Co(II), Mg, Be, Ti(IV), V(IV), Li and Na by eluting these with 2.0M nitric acid from a column containing 54 ml (20 g) of macroporous AG MP-50 cation-exchange resin of 100-200 mesh particle size, in the H(+)-form. Silver is retained and can be eluted with 0.5M hydrobromic acid in 9:1 v v acetone-water. Separations are sharp and quantitative and only a few microg of the other elements are found in the silver fraction. Cadmium and manganese (II) can also be separated quantitatively but show tailing and require larger elution volumes. Some typical elution curves and results of analyses of synthetic mixtures are presented.     

Quantitative separation of gallium from zinc, copper, indium, iron(III) and other elements by cation-exchange chromatography in hydrobromic acid-acetone medium

Gallium can be separated from Zn, Cu(II), In, Cd, Pb(II), Bi(III), Au(III), Pt(IV), Pd(II), Tl(III), Sn(IV) and Fe(III) by elution of these elements with 0.50M hydrobromic acid in 80% acetone medium, from a column of AG50W-X4 cation-exchange resin. Gallium is retained and can be eluted with 3M hydrochloric acid. Separations are sharp and quantitative except for iron(III) which shows extensive tailing. With 0.20M hydrobromic acid in 80% acetone as eluting agent, all the species above except iron(III) and copper(II) can be separated from gallium with very large separation factors. Only a 1-g resin column and small elution volumes are required to separate trace amounts and up to 0.5 mmole of gallium from more than 1 g of zinc or the other elements. Hg(II), Rh(III), Ir(IV), Se(IV), Ge(IV), As(III) and Sb(III) have not been investigated, but should be separated together with zinc according to their known distribution coefficients. Relevant elution curves, results for the analysis of synthetic mixtures and for amounts of some elements remaining in the gallium fraction are presented.     

Separation of traces and minor amounts of lead from large amounts of zinc,indium, gallium and other elements on a low cross-linked anion-exchange resin

Lead is separated from gram amounts of Zn, In, Ga, Fe(III), Cu(II), Co(II), Mn(II), U(VI), Ca and Ba on a short column of AG1-X4 anion-exchange resin in the bromide form. Lead is retained from 0.2 M hydrobromic acid while the other elements are eluted completely with this reagent. Lead is then eluted with 2 M nitric acid. Separations are sharp and quantitative and, especially for gram amounts of zinc, much better than those obtained with an 8% cross-linked resin; up to 10 mg of lead can be separated from 2 g of zinc. Results are given for synthetic mixtures and lead is determined in several analytical grade chemicals.     

Improved separation of cadmium from indium,zinc, gallium and other elements by anion-exchange chromatography in hydrobromic nitric acid mixtures

The separation of cadmium from indium, zinc and many other elements is considerably improved by eluting these elements with 0.1 M hydrobromic–0.5 M nitric acid solution from a column of AG1-X8 resin. Cadmium is retained very strongly and can be eluted with 2 M nitric acid or 1 M ammonia–0.2 M ammonium nitrate solution. Separations are sharp and quantitative and from microgram amounts up to 2 g of indium and zinc are separated from amounts of cadmium ranging from micrograms up to 100 mg on a 2-g (4.6 ml) resin column. Ga(II), Fe(III). Mn(II), Co(II), U(VI) and Ni(II) can be separated quantitatively from cadmium in the same way. The behaviour of numerous elements is discussed, with special attention to lead, and relevant elution curves and results from the analysis of synthetic mixtures are presented.     

Quantitative separation of gold from cadmium, indium, zinc and other elements by cation-exchange chromatography in hydrochloric acid-acetone medium

Gold(III) can be separated from Cd, In. Zn, Ni, Cu(II), Mn(II), Co(II), Mg, Ca, Al, Fe(III), Ga and U(VI) by adsorbing these elements on a column of AG50W-X8 sulphonated polystyrene cation-exchange resin from 0.1M HCl containing 60% v v acetone, while Au(III) passes through and can be eluted with the same reagent. Separations are sharp and quantitative. The amounts of gold retained by the resin are between 1 and 2 orders of magnitude lower than encountered during adsorption from aqueous 0.1M HCl. Recoveries for mg amounts of gold are 99.9% or better and for ng amounts are still better than 99%, as shown by radioactive tracer methods. Hg(II), Bi, Sn(IV), the platinum metals and some elements which tend to form oxy-anions in dilute acid accompany gold. All other elements, though not investigated in detail, should be retained, according to their known distribution coefficients. Relevant elution curves, results of quantitative separations of binary mixtures and of recovery tests are presented.     

Determination of trace elements in manganese metal and compounds by ion-exchange chromatography and atomic absorption spectrometry : part 2. Determination of Bi,Cd, In,Zn, Pb,Fe(III), Ga,Cu(II), Co and U(VI)

Traces of the specified elements are separated from 1 g of manganese (II), using a 30- g column of AG50W-X8 cation-exchange resin and mixtures of hydrochloric acid and acetone as eluents. The trace elements are separated into three groups and are determined by atomic absorption spectrometry, except uranium for which spectrophotometry is used. Recoveries for 10 μg amounts (20 μg for gallium) vary between 94% (for gallium) and 103% (for uranium). A combined elution curve, results for the analysis of synthetic mixtures and for the determination of ten trace elements in samples of manganese metal, chloride and dioxide are presented.     

Separation of nickel from other elements by cation-exchange chromatography in dimethylglyoxime/hydrochloric acid/acetone media

Nickel can be separated from Zn, Co, Cu(II), Mn(II), Fe(III), U(VI) and other elements which readily form chloro complex ions, by eluting them with 0.5 M HCl/93% acetone from AG50W-X4 resin. Nickel is then eluted selectivity with 0.5 M HCl/95% acetone containing 0.1 M dimethylglyoxime, while the alkali and alkaline-earth elements, Al, Ti(IV), Sc, Y, La, lanthanides, Zr, Hf and Th are still retained. Separations are sharp and quantitative.     

Separation of traces and larger amounts of bismuth from gram amounts of thallium, mercury, gold and platinum by cation-exchange chromatography on a macroporous resin

Traces and larger amounts of bismuth (up to 50 mg) can be separated from gram amounts of thallium, mercury, gold and platinum (up to 5 g) by sorption from a mixture of 0.1M hydrochloric acid and 0.4M nitric acid on a column containing just 3 g (8.1 ml) of AGMP-50, a macroporous cation-exchange resin. This resin retains bismuth much more strongly than does the usual microporous resin (styrene-DVB with 8% cross-linkage). Other elements are eluted with the same acid mixture as that used for sorption, and bismuth is finally eluted with 1.0M hydrochloric acid. Separations of bismuth are sharp and recoveries quantitative. Only microgram amounts of the other elements remain in the bismuth fraction. Amounts of bismuth as little as 5 mug have been separated from 5 g of thallium, and determined (r.s.d. = 2%) by flame atomic-absorption. Only 100-mug amounts of bismuth have been separated from gram amounts of mercury, gold, and platinum, but there is no reason to believe that smaller or larger amounts of bismuth cannot be separated from these elements and recovered with the same accuracy as that for the separation from thallium. The lower limit of the method is determination of 0.4 mug of bismuth in 10 ml of solution (0.004 absorbance). An elution curve, the relevant distribution coefficients and the results of analysis of synthetic mixtures and two practical samples [thallium metal and mercury(II) nitrate] are presented.     

Distribution coefficients and ion-exchange selectivities for 46 elements with a macroporous cation-exchange resin in hydrochloric acid-acetone medium

Distribution coefficients with the macroporous cation-exchange resin AG MP-50 in HCl-acetone mixtures ranging from 0.2 to 4.0M HCl and from 0 to 95% acetone have been determined for 46 elements. The ion-exchange behaviour of the elements is discussed, some possible separations are indicated, and elution curves demonstrating separations of the combinations Au(III)BiZnPbSr; Rh(III)InGaCuNi and CdFe(III)LiAlYb are presented.     

Quantitative separation of lanthanides and scandium from barium,strontium and other elements by cation-exchange chromatography in nitric acid

The lanthanides plus yttrium and scandium are separated from Ba, Sr, Ca, Mg, Pb(II), Bi(III), Zn, Mn(II) and U(VI) by eluting these elements with 2.0 M nitric acid from a column of AG50W-X8 cation exchange resin (200-400 mesh). The lanthanides are retained and can then be eluted with 4 M nitric or hydrochloric acid. Separations are quantitative and applicable to microgram and millimolar amounts of the lanthanides and the other elements. Elements such as Cu(II), Co(II), Ni(II), Cd. Hg(II), T1(I). Ag, Be, Ti(IV) and the alkali metals should accompany barium quantitatively according to their known distribution coefficients. Relevant elution curves and results of analysis of synthetic mixtures are presented.     

Separation of bismuth from gram amounts of thallium and silver by cation-exchange chromatography in nitric acid

Traces and small amounts of bismuth can be separated from gram amounts of thallium and silver by successively eluting these elements with 0.3M and 0.6M nitric acid from a column containing 13 ml (3 g) of AG50W-X4, a cation-exchanger (100-200 mesh particle size) with low cross-linking. Bismuth is retained and can be eluted with 0.2M hydrobromic acid containing 20% v/v acetone, leaving many other trace elements absorbed. Elution of thallium is quite sharp, but silver shows a small amount of tailing (less than 1 gmg/ml silver in the eluate) when gram amounts are present, between 20 and 80 mug of silver appearing in the bismuth fraction. Relevant elution curves and results for the analysis of synthetic mixtures containing between 50 mug and 10 mg of bismuth and up to more than 1 g of thallium and silver are presented, as well as results for bismuth in a sample of thallium metal and in Merck thallium(I) carbonate. As little as 0.01 ppm of bismuth can be determined when the separation is combined with electrothermal atomic-absorption spectrometry.     

Separation of trace amounts of indium, gallium and aluminium from each other by cation-exchange chromatography on AG50-X4 resin

Traces and minor amounts of indium, gallium and aluminium can be separated from gram amounts of thallium and from each other by cation-exchange chromatography on a column containing as little as 2 g of AG50W-X4, a cation-exchange resin with low cross-linking. An elution sequence of 0.1 M HBr in 40% acetone [for Tl(III)], 0.2M HBr in 80% acetone for In, 0.3M HCl in 90% acetone for Ga and 3M aqueous HCl for Al is used. The separations are very sharp and even 10-mug amounts of In, Ga and Al in synthetic mixtures are recovered quantitatively, with a standard deviation of 0.3 mug. The separation factors between neighbouring ions are extremely large (> 5000).     

Selective separation of uranium from other elements by cation-exchange chromatography in hydrobromic acid and hydrochloric acid-acetone mixtures

U(VI) can be separated from Ga, Fe(III), Bi, Pb, Cd, Zn, Cu(II) and Au(III) by quantitative elution with 0.50M HBr in 86% acetone or with 0.35M HBr in 90% acetone from a column of AG50W-X4 cation-exchange resin of 200-400 mesh particle size. U(VI) and many other ions are retained. U(VI) then can be eluted selectively with 0.50M HCl in 83% acetone or with 0.35M HCl in 85% acetone. Co(II), Mn(II), Mg, Ca, Ti(IV), Al, Zr, Th and La are quantitatively retained by the column. These elements then can be eluted with 5M HNO(3). At the higher acid concentration (0.50M) the separation between U(VI) and Li is not satisfactory but is excellent at the lower acid concentration; the U(VI) peak is sharper at the higher acid concentration. Separations are sharp and quantitative, as is demonstrated by results for some synthetic mixtures. Distribution coefficients and elution curves are presented.     

Quantitative separation of beryllium from magnesium,calcium, aluminium,iron and other elements by cation-exchange chromatography in nitric acid-methanol

Beryllium is separated from Mg, Ca, Mn(II), Fe(III), Al, Co(II). Zn. U(VI), La and Gd by elution with 2.0 M nitric acid in 70 % methanol from a column of AG50W-X8 sulphonated polystyrene cation exchanger, while the other elements are retained quantitatively. Sr, Ba, Sc, Y, the other lanthanides, Zr, Hf, Th, Ga, In, Cd and Ni(II) should also be separated according to their distribution coefficients or elution behaviour. Separations are sharp and recoveries quantitative from millimolar amounts down to 10 μg of beryllium. The separation of Ti(IV) and Cu(II) from beryllium is not satisfactory and requires rather large columns. Bi(III), Pb(II), Hg(II) and the alkali metals are eluted together with beryllium, but can be separated by other methods. Typical elution curves and results for the quantitative separation of binary synthetic mixtures are presented.     

Accurate determination of trace amounts of thorium in silicate rocks by cation-exchange chromatography and spectrophotometry

Thorium in four of the South African NIMROC standards and in four secondary standards is determined accurately by means of spectrophotometry with arsenazo-III after a selective cation-exchange separation on an AG50W-X4 resin column. All other elements are eluted with 6 M hydrobromic acid before the final elution of thorium with 5 M nitric acid. Small amounts of zirconium which may be present in the thorium eluate, are effectively complexed with oxalic acid which also eliminates the spectrophotometric interferences caused by organic material leached from the resin column. The accuracy and precision of the method are demonstrated by the analysis of synthetic mixtures containing various amounts of thorium. Amounts of 10 and 100 μg of thorium can finally be determined with coefficients of variation of 1% and 0.2%, respectively.     

Improved separation of iron from copper and other elements by anion-exchange chromatography on a 4% cross-linked resin with high concentrations of hydrochloric acid

Iron(III) can be separated from copper(II) and many other elements by eluting these from a column of AG1-X4 anion-exchange resin with 8M hydrochloric acid, while iron(III) is retained and can be eluted with 0.1M hydrochloric acid. The separation is much better than the customary one with 3.5M hydrochloric acid. Columns containing only 8.8 ml (3 g) of resin can separate traces or up to more than 1 mmole of iron(III) from more than 1 g of copper. Mn(II), Ni, Al, Mg and Ca are quantitatively eluted together with copper(II). Lead, the alkali metals, Be, Sr, Ba, Ra, Sc, Y and the lanthanides, Ti(IV), Zr, Hf, Th and Cr(III) have not been investigated in detail but should be separated according to their known distribution coefficients. Separations are sharp and quantitative, less than 1 mug of copper remaining in the iron fraction when more than 1 g was present originally. Relevant elution curves and results of the quantitative analysis of synthetic mixtures are presented.     

Distribution coefficients and cation-exchange behaviour of 45 elements with a macroporous resin in hydrochloric acid/methanol mixtures

Cation-exchange distribution coefficients are presented for 45 elements with the macroreticular (macroporous) cation-exchange resin AG MP-50 in mixed hydrochloric acid/methanol media, with acid concentrations ranging from 0.5 to 6.0 M, and methanol concentrations from 0 to 90%. The ion-exchange behaviour of the elements is discussed, some possible separations are indicated, and 3 multi-element elution curves are presented, demonstrating the separations of the combinations In-Zn-Ga-Al-Yb; Cd-Li-Cu(II)-Mg-Ca; and Pt(IV)-Te(IV)-V(IV)-Fe(III)-Mn(II).