Determination of copper, cadmium and lead in seawater and mineral water by flame atomic absorption spectrometry after coprecipitation with aluminum hydroxide

An aluminum hydroxide coprecipitation method for the determination of cadmium, copper and lead by flame atomic absorption spectrometry in aqueous solutions, seawater and mineral water samples has been investigated. The coprecipitation conditions, such as the effect of the pH, the amount of carrier element, the effect of possible matrix ions and the time were examined in detail for the studied elements. It was found that cadmium, copper and lead are co-precipitated quantitatively (≥95%) with aluminum hydroxide at pH 7 with low R.S.D. values of around 2 to 3%. Detection limits (38) were 6 ng ml⁻¹ for Cd, 3 ng ml⁻¹ for Cu and 16 ng ml⁻¹ for Pb. The method proposed was validated by the analysis of HPS 312205 seawater standard reference material and spiked mineral water samples.     

Determination of indium by graphite furnace atomic absorption spectrometry after coprecipitation with chitosan.

A sensitive and simple method for the determination of trace amounts of indium in water samples by graphite furnace atomic absorption spectrometry (GFAAS) after coprecipitation with chitosan was investigated. Indium was quantitatively preconcentrated from water samples by coprecipitation with chitosan at pH 7.0-9.0. The coprecipitant was easily dissolved with acetic acid, and indium in the resulting solution was determined by GFAAS. The addition of lanthanum as a chemical modifier was more effective for the atomic absorbance of indium. The detection limit (S/N > or = 3) for indium was 0.04 microg dm(-3), and the relative standard deviations (n = 5) were 3.5-4.5% at 1.0 microg/100 cm3. The results obtained in this study indicate that the proposed method can be successfully applied to the determination of trace indium in water samples.     

Coprecipitation with lanthanum phosphate as a technique for separation and preconcentration of iron(III) and lead

The usefulness of coprecipitation with lanthanum phosphate for separation and preconcentration of some heavy metals has been investigated. Although lanthanum phosphate coprecipitates iron(III) and lead quantitatively at pH 2.3, iron(II) can barely be collected at this pH. This coprecipitation technique was applicable to the separation and preconcentration of iron(III) before inductively coupled plasma atomic-emission spectrometric (ICP-AES) determination; the recoveries of iron(III) and iron(II) from spiked water samples were 103-105% and 0.2-0.7%, respectively. The coprecipitation was also useful for separation of 20 microg lead from 100 mL of an aqueous solution that also contained 1-100 mg iron. Coprecipitation of iron was substantially suppressed by addition of ascorbic acid, which enabled recovery of 97-103% of lead added to the solution, bringing the recovery to within 1.6-5.0% of the relative standard deviations. Lanthanum phosphate can also coprecipitate cadmium and indium quantitatively, although chromium(III), cobalt, and nickel and large amounts of sodium, potassium, magnesium, and calcium are barely coprecipitated at pH approximately/= 3.     

Determination of trace iron in indium phosphide wafer by on-line matrix separation and inductively coupled plasma mass spectrometry

A method for the determination of iron in indium phosphide (InP) wafer is proposed. In the present experiment, an on-line matrix separation system using an ion exchange column was combined with inductively coupled plasma mass spectrometry (ICP-MS) for the determination of ng g⁻¹ level of iron. In the on-line matrix separation, indium and iron in the sample solution was passed through a strongly-basic anion exchange resin column with the 9 M HCl carrier solution, where indium was eluted from the column and iron was adsorbed on it. Then, iron was eluted with the carrier solution of 0.3 M HCl containing 1 ng ml⁻¹ cobalt, and it was directly introduced into the ICP-MS nebulizer. In ICP-MS measurement, cobalt in the carrier solution was used as an internal standard to correct the change in sensitivity due to matrix effect, and the peak area integration was performed to quantify iron and cobalt in the integration time range of 20-60 s from the start of the cobalt solution flow. The detection limit (3σ) for iron was 3 ng g⁻¹, and the recoveries for iron in the 0.8, 2.4, and 8.0% indium solutions were almost 100%. The method was applied to the determination of iron in commercially available iron-doped InP wafers. The obtained results for InP wafer samples with the high iron concentration were in good agreement with those obtained by graphite furnace atomic absorption spectrometry (GFAAS).     

Application of internal standardization to rapid coprecipitation technique using lanthanum phosphate for flame atomic absorption spectrometric determination of iron and lead.

By applying an internal standardization, we could use a rapid coprecipitation technique using lanthanum phosphate as a coprecipitant for preconcentration of iron(III) and lead in their flame atomic absorption spectrometric determination. Indium as an internal standard was added to the initial sample solution together with lanthanum and phosphoric acid; the coprecipitation of iron(III) and lead was then carried out at pH about 3. After measuring the atomic absorbances of iron, lead, and indium in the final sample solution, we determined the contents of iron(III) and lead in the original sample solution by using the internal standardization with indium. In this method, complete collection of the precipitate was not required after the coprecipitation of iron(III), lead, and indium, because the ratio of the recovery of iron(III) or lead to that of indium was almost constant regardless of the recovery of the precipitate. This method was simple and rapid, and was available for the determination of 2-300 micrograms L-1 of iron(III) and 5-400 micrograms L-1 of lead in some water samples.     

电感耦合等离子体原子发射光谱(ICP-AES)法测定再生锌原料中铜、铅、铁、铟、镉、砷、钙、铝

采用硝酸、盐酸、氢氟酸(氟化氢铵)、高氯酸分解样品,电感耦合等离子体原子发射光谱法测定了再生锌原料中铜、铅、铁、铟、镉、砷、钙、铝的量。其测定范围:ω(Cu):0.01%～0.60%;ω(Pb):0.10%～5.00%;ω(Fe):0.10%～5.00%;ω(In):0.0100%～0.200%;ω(Cd):0.010%～3.00%;ω(As):0.10%～2.00%;ω(Ca):0.10%～10.00%;ω(Al):0.10%～4.00%。各元素的加标回收率为93%～113%。方法准确、快速、可靠,适用于再生锌原料中铜、铅、铁、铟、镉、砷、钙、铝量的同时测定。     

Direct determination of cadmium and copper in seawater using a transversely heated graphite furnace atomic absorption spectrometer with Zeeman-effect background corrector

Methods for the direct determination of copper and cadmium in seawater were described using a graphite furnace atomic absorption spectrometer (GFAAS) equipped with a transversely heated graphite atomizer (THGA) and a longitudinal Zeeman effect background corrector. Ammonium nitrate was used as the chemical modifier to determine copper. The mixture of di-ammonium hydrogen phosphate and ammonium nitrate was used as the chemical modifier to determine cadmium. The matrix interference was removed completely so that a simple calibration curve method could be applied. This work is the first one with the capability of determining cadmium in unpolluted seawater directly with GFAAS using calibration curve based on simple aqueous standards. The accuracy of the methods was confirmed by analysis of three kinds of certified reference saline waters. The detection limits (LODs), with injection of a 20-mul aliquot of seawater sample, were 0.06 mug l(-1) for copper and 0.005 mug l(-1) for cadmium.     

Studies on extraction of Cu(II), Ga(III), In(III) and Tl(III) with 1-phenyl-3-methyl-4-benzoylpyrazol-5-one Separation and spectrophotometric determination of copper and gallium

The extraction of Cu(II), Ga(III), In(III) and Tl(III) with 1-phenyl-3-methyl-4-benzoylpyrazol-5-one (HPMBzP) from aqueous solutions has been investigated. The mechanism of extraction and the composition of the species extracted has been determined. The effect of equilibration time, various organic solvents and salting-out agents on the extraction of copper and gallium has also been investigated. The green Cu(PMBzP)₂ chelate has absorption maxima at 298 and 670 nm, and PMBzP has maximum absorbance at 290 nm. A new and sensitive spectrophotometric method for copper has been devised, based on the absorbance at 670 nm. The presence of excess of reagent does not interfere and no special treatment is necessary to destroy it. The proposed method has some advantages and has been applied for the determination of copper in various soil samples. Gallium has been separated from indium, thallium, copper, iron and many other elements. The recovery of gallium and copper was 100 ± 0.2%.     

Electrosurface Properties of Hydr(oxides) and Oxide Nanostructures in 1 : 1 Electrolyte Solutions: 1. Adsorption Characteristics of Boehmite, Goethite, and Silicon Dioxide

The adsorption of potential-determining ions on aluminum and iron hydroxides and silicon dioxide was measured in KCl and NaCl background solutions. It was shown that dependences of the adsorption on pH and the concentration of a background 1 : 1 electrolyte (NaCl) have the shape characteristic of oxide surfaces; the of values pH_PZCwere determined. Results of adsorption measurements were used for the determination of constants of surface reactions and adsorption potentials of ions in terms of the 2-pK model.     

Determination of some trace elements in food and soil samples by atomic absorption spectrometry after coprecipitation with holmium hydroxide

The determination of trace elements in food and soil samples by atomic absorption spectrometry was investigated. A coprecipitation procedure with holmium hydroxide was used for separation-preconcentration of trace elements. Trace amounts of copper(II), manganese(II), cobalt(II), nickel(ll), chromium(lll), iron(Ill), cadmium(ll), and lead(ll) ions were coprecipitated with holmium hydroxide in 2.0 M NaOH medium. The optimum conditions for the coprecipitation process were investigated for several commonly tested experimental parameters, such as amount of coprecipitant, effect of standing time, centrifugation rate and time, and sample volume. The precision, based on replicate analysis, was lower than 10% for the analytes. In order to verify the accuracy of the method, the certified reference materials BCR 141 R calcareous loam soil and CRM 025-050 soil were analyzed. The procedure was successfully applied for separation and preconcentration of the investigated ions in various food and soil samples. An amount of the solid samples was decomposed with 15 mL concentrated hydrochloric acid-concentrated nitric acid (3 + 1). The preconcentration procedure was then applied to the final solutions. The concentration of trace elements in samples was determined by atomic absorption spectrometry.     

Rapid coprecipitation-separation and flame atomic absorption spectrometric determination of lead and cadmium in water with cobalt (II) and ammonium pyrrolidine dithiocarbamate

A coprecipitation technique which does not require complete collection of the precipitate was proposed for the determination of trace lead and cadmium in water with flame atomic absorption spectrometry (FAAS) after preconcentration of lead and cadmium by using cobalt (II) and ammonium pyrrolidine dithiocarbamate (Co-APDC) as coprecipitant and known amount of cobalt as an internal standard. Since lead, cadmium and cobalt were well distributed in the homogeneous precipitate, the concentration ratio of lead to cobalt, and cadmium to cobalt remained unchanged in any part of the precipitate. The amount of lead and cadmium in the original sample solution can be calculated respectively from the ratio of the absorbance values of lead and cadmium to cobalt in the final sample solution that is measured by FAAS and the known amount of the lead and cadmium in the standard series solutions. The optimum pH range for quantitative coprecipitation of lead and cadmium is from 3.0 to 4.5. The 16 diverse ions tested gave no significant interferences in the lead and cadmium determination. Under optimised conditions, lead ranging from 0 to 40?µg and cadmium ranging from 0 to 8?µg were quantitatively coprecipitated with Co-APDC from 100?mL sample solution (pH?～?3.5). This coprecipitation technique coupled with FAAS was applied to the determination of lead and cadmium in water samples with satisfactory results (recoveries in the range of 94.0–108%, relative standard deviations <6.0%).     

Spectrophotometric determination of traces of gallium and indium with 1-(2-pyridylazo)-2-naphthol

1-(2-Pyridylazo)-2-naphthol (PAN) reacts with either gallium or indium at pH 5–6 giving a red complex in an aqueous medium in the presence of N.N-dimethyl-formamide. The maximum absorption of both PAN complexes of gallium and indium in an aqueous solution is at 545 mμ. The gallium-PAN complex shows a characteristic enhancement of color by addition of small amounts of ethers. Based on this selective enhancement reaction, gallium can be determined in the presence of other metals without separation. The results of determining gallium and indium in the presence of each other are reported. Both gallium and indium form M₂(PAN)₃; but in the presence of certain organic solvents, a different gallium complex, Ga(PAN)₅, and the same indium complex, In₂(PAN)₃, are formed. The reaction of PAN with cadmium can be masked by iodide; an example of determining indium in the presence of cadmium is given. The PAN method has a sensitivity of 0.003 μg/cm² for gallium and 0.005μg/cm² for indium and an absorptivity of 24,900 for the Ga-PAN complex and of 24,500 for the In-PAN complex, respectively. The methods have been successfully applied to the determination of both gallium and indium in germanium thin films.     

Concentration of heavy metal ions in water using thermoresponsive chelating polymer

Thermoresponsive polymers, poly(N-isopropylacrylamide) (PNIPAAm), having chelating functionalities were synthesized. PNIPAAm-imidazole (-Im) was precipitated and formed a gum-like aggregate in the neutral pH region at 50 °C, while PNIPAAm-carboxylic acid (---COOH) and PNIPAAm-iminodiacetic acid (-IDA) remained soluble even at pH 7. An addition of a paired ion, dodecyltrimethylammonium ion, was effective for inducing the precipitation of those polymers. PNIPAAm-Im was useful for collecting copper(II), nickel(II), cobalt(II), and lead(II), but was ineffective for cadmium(II) recovery. In contrast, PNIPAAm-COOH collected cadmium(II), while insufficiently recovered cobalt(II) and nickel(II). PNIPAAm-IDA was the best choice for collecting all metal ions in neutral pH's. After 20-folds concentration, the metal ions in river and seawater were successfully determined by graphite furnace atomic absorption spectrometry (GFAAS).     

Application of a metal ion-imprinted polymer based on salen-Cu complex to flow injection preconcentration and FAAS determination of copper

A new Cu(II)-imprinted polymer (Cu-IIP) for preconcentration of copper by liquid-solid extraction via flow injection technique has been proposed. Cu-IIP was obtained by copolymerization of salen-Cu(II) complex with styrene and divinylbenzene using suspension polymerization technique. Granules fraction of 60-80 microm in diameter was used as a microcolumn packing. Cu(II) sorption was proved to be the most effective from solutions of pH 7, whereas similar elution effectiveness was observed when applying as eluents hydrochloric or nitric acid in the concentration range of 0.5-10% (v/v). The system exhibited good long-term stability and acid resistance. Batch sorbent capacity was found to be 0.11 mmol g(-1) of a dry polymer. Enrichment factor (EF) for 30 s loading time was 16. Preconcentration of Cu(II) and potentially interfering metal ions is strongly pH dependent. Examination of Cu(II) sorption in the presence of Pb(II), Cd(II), Zn(II) and Ag(I) showed significant influence of cadmium and zinc ions only and that was for the interferent concentrations above 0.5 mg L(-1) (Cu-IIP mass of ca. 35 mg). The interference effect was reduced with the sorbent mass increase. Fe(III) and Mn(II) ions, present in treated tap water in relatively high concentrations, did not interfere. Effective pH adjusting of the loaded solution in on-line mode, when applying diluted Clark-Lubs buffering solution, allowed accurate copper determination in tap water (compared to graphite furnace atomic absorption spectrometry, GFAAS) using standard addition or combination calibration method.     

Determination of silver, antimony, bismuth, copper, cadmium and indium in ores, concentrates and related materials by atomic-absorption spectrophotometry after methyl isobutyl ketone extraction as iodides

Methods for determining ~ 0.2 mug g or more of silver and cadmium, ~ 0.5 mug g or more of copper and ~ 5 mug g or more of antimony, bismuth and indium in ores, concentrates and related materials are described. After sample decomposition and recovery of antimony and bismuth retained by lead and calcium sulphates, by co-precipitation with hydrous ferric oxide at pH 6.20 +/- 0.05, iron(III) is reduced to iron(II) with ascorbic acid, and antimony, bismuth, copper, cadmium and indium are separated from the remaining matrix elements by a single methyl isobutyl ketone extraction of their iodides from ~2M sulphuric acid-0.1M potassium iodide. The extract is washed with a sulphuric acid-potassium iodide solution of the same composition to remove residual iron and co-extracted zinc, and the extracted elements are stripped from the extract with 20% v v nitric acid-20% v v hydrogen peroxide. Alternatively, after the removal of lead sulphate by filtration, silver, copper, cadmium and indium can be extracted under the same conditions and stripped with 40% v v nitric acid-25% v v hydrochloric acid. The strip solutions are treated with sulphuric and perchloric acids and ultimately evaporated to dry ness. The individual elements are determined in a 24% v v hydrochloric acid medium containing 1000 mug of potassium per ml by atomic-absorption spectrophotometry with an air-acetylene flame. Tin, arsenic and molybdenum are not co-extracted under the conditions above. Results obtained for silver, antimony, bismuth and indium in some Canadian certified reference materials by these methods are compared with those obtained earlier by previously published methods.     

Simultaneous determination of metals in two-component mixtures with 5-sulfo-8-quinolinol by using phase-resolved fluorimetry

Determinations of metals in two-component mixtures are described in which 5-sulfo-8-quinolinol is used to produce fluorescent chelates of the metals. The metal chelates have broad, overlapping fluorescence spectra but the fluorescence lifetimes (τ) of the chelates are sufficiently different to permit phase-resolved fluorimetric determinations in which the fluorescence contributions of the two chelates can be resolved. Average determination errors ranged from ?4.1% to 2.1% for each metal chelate in mixtures of zinc and cadmium (Δτ = 1.0 ns), gallium and indium (Δτ = 1.7 ns) and aluminum and gallium (Δτ = 5.3 ns). Limits of detection and determination for each individual metal chelate were found to be three times and five times greater, respectively, for the phase-resolved measurements relative to steady-state measurements under the same experimental conditions. Effects of pH on the fluorescence lifetimes and intesities of the metal chelates were studied.     

Analytical procedure for the simultaneous voltammetric determination of toxic metals in dialysis fluids

A new analytical voltammetric procedure for the simultaneous determination of copper(II), lead(II), cadmium(II), zinc(II), chromium(VI), and manganese(II) in two kinds of dialysis fluid (peritoneal and haemodialysis fluids) is described. The voltammetric measurements were performed using, as working electrode, a stationary mercury electrode, and a platinum electrode and a Agmid R:AgClmid R:KCl ((sat.)) electrode as auxiliary and reference electrodes, respectively, employing 0.1 mol L(-1) dibasic ammonium citrate solution pH 6.9 as supporting electrolyte. For all the elements, the accuracy, expressed as relative recovery R%, was very satisfactory being in the range 94-105%, the precision, expressed as relative standard deviation s(r)%, was lower than 6%, while the limits of detection were of the order of a few units of microg L(-1). The analytical voltammetric procedure has been validated by comparison with spectroscopic (graphite furnace atomic absorption spectroscopy, GFAAS) measurements.     

The application of 5,5,7,12,12,14-hexamethyl-1,4,8,11-tetraazacyclotetradecane to the extraction of metal ions

The use of 5,5,7,12,12,14-hexamethyl-1,4,8,11-tetraazacyclotetradecane (Tet) in chloroform solutions provides quantitative extraction of lead(II), cadmium(II), copper(II) and zinc(II) at different pH values from solutions containing perchlorate and cyclohexanecarboxylic acid. Nickel(II) and cobalt(II) ions are not extracted quantitatively. Single extractions of mixtures of copper with transition metals gave the best separations for the copper/nickel system. Separations of copper from cobalt, lead, manganese and iron were less satisfactory.     

Flame atomic absorption spectrometric determination of lead in waste water and effluent after preconcentration using a rapid coprecipitation technique with gallium phosphate

A determination method for lead in waste water and effluent was studied using flame atomic absorption spectrometry after preconcentration of lead by the rapid coprecipitation technique with gallium phosphate. Lead ranging from 0.5 to 50 microg was quantitatively coprecipitated with gallium phosphate from 100-150 mL sample solution (pH approximately 5). The presence of gallium phosphate did not affect the atomic absorbance of lead. Since the concentration of gallium in the final sample solution is also measurable by flame atomic absorption spectrometry at 250.0 nm without further dilution, the rapid coprecipitation technique, which does not require complete collection of the precipitate, becomes possible using a known amount of gallium and measuring the concentrations of both lead and gallium in the final sample solution by flame atomic absorption spectrometry. The 32 diverse ions tested gave no significant interferences in the lead determination. The method proposed here is rapid and has good reproducibility.     

Kinetic spectrophotometric determination of indium/gallium mixtures

A kinetic method is presented for the determination of 0.5–5 μg ml^?1 gallium based on its activating effect on the copper(II)-catalyzed oxidation of 4,4′-dihydroxybenzophenone thiosemicarbazone by hydrogen peroxide. The reaction is monitored spectrophotometrically at 415 nm. Two sets of reaction conditions are established; one for the direct determination of gallium, and another, in which indium affects the gallium response, for determination of indium. Mixtures of these cations can be determined at μg ml^?1 levels and in gallium/indium ratios from 7.5:1 to 1:1.6, with an accuracy and precision of ca. 4.5%.