Dysprosium(III) hydroxide coprecipitation system for the separation and preconcentration of heavy metal contents of table salts and natural waters

A procedure for the determination of trace amounts of Pb(II), Cu(II), Ni(II), Co(II), Cd(II) and Mn(II) is described, that combines atomic absorption spectrometry-dysprosium hydroxide coprecipitation. The influences of analytical parameters including amount of dysprosium(III), centrifugation time, sample volume, etc. were investigated on the recoveries of analyte ions. The effects of concomitant ions were also examined. The recoveries of the analyte ions were in the range of 95.00-104.00%. The detection limits corresponding to three times the standard deviation of the blank for the analytes were in the range of 14.1-25.3 microg/L. The method was applied to the determination of lead, copper, nickel, cobalt, cadmium and manganese ions in natural waters and table salts good results were obtained (relative standard deviations <10%, recoveries >95%).     

Bacillus thuringiensis var. israelensis immobilized on Chromosorb 101: a new solid phase extractant for preconcentration of heavy metal ions in environmental samples

Bacillus thuringiensis var. israelensis immobilized on Chromosorb 101 that is a new solid phase extractor has been presented at this work for the preconcentration and separation of cadmium(II), lead(II), manganese(II), chromium(III), nickel(II) and cobalt(II) in environmental samples. The analytical parameters including pH of aqueous solutions, sample volume, eluent types, etc. were investigated for the quantitative recoveries of the analytes. The influences of the some metal ions as concomitant were investigated. Under the optimized conditions, the detection limits by 3sigma for analyte ions were in the range of 0.37-2.85 microg L(-1). The accuracy of the developed procedure was confirmed by IAEA 336 Lichen and NIST SRM 1573a Tomato leaves certified reference materials. The method was also applied successfully to the determination of analytes in microwave digested red wine, rice and canned fish samples and sea water, spring water and urine samples.     

Celtek clay as sorbent for separation-preconcentration of metal ions from environmental samples

The sorption conditions including pH of the aqueous solution, sample volume, etc., on Celtek clay of copper(II), cadmium(II), lead(II), chromium(III), nickel(II) and cobalt(II) ions from environmental samples has been studied. The effects of electrolytes as matrix on the preconcentration were also investigated with the recoveries >95%. The 3 sigma detection limits for copper, cadmium, lead, chromium, nickel and cobalt ions were found to be 0.25, 0.32, 0.73, 0.45, 0.50 and 0.41 microg/l, respectively. The relative standard deviation was <10% for the determination of analytes. The procedure was validated by analysis of a NRCC-SLRS 4 Riverine Water, SRM 1573a Tomato leaves and IAEA 336 Lichen standard reference materials. The developed method was successively utilized for the determination of Cu(II), Cd(II), Pb(II), Cr(III), Ni(II) and Co(II) in various samples including natural waters, wheat and human hair by flame atomic absorption spectrometry (FAAS) with satisfactorily results (recoveries>95% and R.S.D.'s<10%).     

Column solid-phase extraction of nickel and silver in environmental samples prior to their flame atomic absorption spectrometric determinations

A biosorption procedure for preconcentration-separation of nickel(II) and silver(I) at trace levels on Bacillus sphaericus-loaded Chromosorb 106 (BSLC106) has been presented in this work. The conditions like pH, amounts of microorganism, eluent type, etc. for the quantitative adsorption of the analyte ions on BSCL106 column were investigated. The analyte ions were quantitatively recovered and desorbed at pH range of 6.0-7.0 and 10 mL of 1M HCl, respectively. The effects of various cationic and anionic interferences on the recoveries of nickel(II) and silver(I) were studied. The detection limits for nickel(II) and silver(I) are 1.42 and 1.05 microg L(-1), respectively. The accuracy of the developed procedure was tested by analyzing NIST SRM 2711 Montana soil and GBW 07310 Stream sediment certified reference materials. The proposed enrichment-separation procedure was successfully applied to the determination of analytes in natural water, black tea, tobacco, soil and sediment samples with satisfactory results.     

A biosorption system for metal ions on Penicillium italicum-loaded on Sepabeads SP 70 prior to flame atomic absorption spectrometric determinations

A solid phase extraction (SPE) preconcentration system, coupled to a flame atomic absorption spectrometer (FAAS), was developed for the determination of copper(II), cadmium(II), lead(II), manganese(II), iron(III), nickel(II) and cobalt(II) ions at the microg L(-1) levels on Penicillium italicum-loaded on Sepabeads SP 70. The analytes were adsorbed on biosorbent at the pH range of 8.5-9.5. The adsorbed metals were eluted with 1 mol L(-1) HCl. The influences of the various analytical parameters including pH of the aqueous solutions, sample volume, flow rates were investigated for the retentions of the analyte ions. The recovery values are ranged from 95-102%. The influences of alkaline, earth alkaline and some transition metal ions were also discussed. Under the optimized conditions, the detection limits (3s, n=21) for analytes were in the range of 0.41microg L(-1) (cadmium) and 1.60microg L(-1) (iron). The standard reference materials (IAEA 336 Lichen, NIST SRM 1573a Tomato leaves) were analyzed to verify the proposed method. The method was successfully applied for the determinations of analytes in natural water, cultivated mushroom, lichen (Bryum capilare Hedw), moss (Homalothecium sericeum) and refined table salt samples.     

Separation,preconcentration and inductively coupled plasma-mass spectrometric (ICP-MS) determination of thorium(IV), titanium(IV), iron(III), lead(II) and chromium(III) on 2-nitroso-1-naphthol impregnated MCI GEL CHP20P resin

A simple and effective method is presented for the separation and preconcentration of Th(IV), Ti(IV), Fe(III), Pb(II) and Cr(III) by solid phase extraction on 2-nitroso-1-naphthol impregnated MCI GEL CHP20P resin prior to their inductively coupled plasma-mass spectrometric determinations. The influence of analytical parameters including pH of the aqueous solution, flow rates of sample and eluent solutions and sample volume on the quantitative recoveries of analyte ions was investigated. Matrix effects caused by the presence of alkali, earth alkali and some metal ions in the analyzed solutions were investigated. The presented solid phase extraction method was applied to BCR-144R Sewage Sludge (domestic origin), BCR-141R Calcareous Loam Soil, NIST 1568a Rice Flour and NIST 1577b Bovine Liver certified reference materials (CRMs) for the determination of analyte ions and the results were in good agreement with the certified values. The separation procedure presented was also applied to the various natural water samples collected from Turkey with satisfactory results.     

Preconcentration and separation of nickel, copper and cobalt using solid phase extraction and their determination in some real samples

A solid phase extraction method has been developed to separate and concentrate trace amounts of nickel, cobalt and copper ions from aqueous samples for the measurement by flame atomic absorption spectrometry. By the passage of aqueous samples through activated carbon modified by dithioxamide (rubeanic acid) (DTO), Ni2+, Cu2+ and Co2+ ions adsorb quantitatively. The recoveries of analytes at pH 5.5 with 500 mg solid phase were greater than 95% without interference from alkaline, earth alkaline and some metal ions. The enrichment factor was 330. The detection limits by three sigma were 0.50 microg L(-1) for copper, 0.75 microg L(-1) for nickel and 0.80 microg L(-1) for cobalt. The loading capacity was 0.56 mg g(-1) for Ni2+, 0.50 mg g(-1) for Cu2+ and 0.47 mg g(-1) for Co2+. The presented procedure was applied to the determination of analytes in tap, river and sea waters, vegetable, soil and blood samples with successfully results (recoveries greater than 95%, R.S.D. lower than 2% for n=3).     

Preconcentration of Pb(II), Cr(III), Cu(II), Ni(II) and Cd(II) ions in environmental samples by membrane filtration prior to their flame atomic absorption spectrometric determinations

A method for separation-preconcentration of Pb(II), Cr(III), Cu(II), Ni(II) and Cd(II) ions by membrane filtration has been described. The method based on the collection of analyte metal ions on a cellulose nitrate membrane filter and determination of analytes by flame atomic absorption spectrometry (FAAS). The method was optimized for several parameters including of pH, matrix effects and sample volume. The recoveries of analytes were generally in the range of 93-100%. The detection limits by 3 sigma for analyte ions were 0.02microgL(-1) for Pb(II), 0.3microgL(-1) for Cr(III), 3.1microgL(-1) for Cu(II), 7.8microgL(-1) for Ni(II) and 0.9microgL(-1) for Cd(II). The proposed method was applied to the determination of lead, chromium, copper, nickel and cadmium in tap waters and RM 8704 Buffalo River Sediment standard reference material with satisfactory results. The relative standard deviations of the determinations were below 10%.     

Diaion SP-850 resin as a new solid phase extractor for preconcentration-separation of trace metal ions in environmental samples

A solid phase extraction method was developed for the preconcentration and separation of trace amounts of chromium, manganese, iron, cobalt, copper, cadmium and lead from environmental samples by complexation with alpha-benzoin oxime followed by adsorption onto Diaion SP-850-solid phase extraction column. One molar per liter HNO(3) was used as eluent. The recoveries of analytes at pH 8.0 with 700 mg of resin were greater than 95% without interference from alkaline, earth alkaline and some metal ions. The detection limits by three sigma for analyte ions were 0.65 microg l(-1) for Cr(III), 0.42 microg l(-1) for Mn(II), 0.28 microg l(-1) for Fe(III), 0.73 microg l(-1) for Co(II), 0.30 microg l(-1) for Cu(II), 0.47 microg l(-1) for Cd(II) and 0.50 microg l(-1) for Pb(II). The validation of the procedure was performed by the analysis of the certified standard reference materials. The presented procedure was applied to the determination of analytes in tap, river and sea waters, rice, wheat, canned tomato and coal samples with successfully results (recoveries greater than 95%, R.S.D.'s lower than 8%).     

Coprecipitation of gold(III), palladium(II) and lead(II) for their flame atomic absorption spectrometric determinations

An enrichment-separation procedure based on the coprecipitation of gold(III), palladium(II) and lead(II) ions with nickel(II)-5-methyl-4-(2-thiazolylazo) resorcinol complex has been developed. The analytical parameters including pH, amounts of 5-methyl-4-(2-thiazolylazo) resorcinol, sample volume, etc. was investigated for quantitative recoveries of Au(III), Pd(II) and Pb(II). Interference due to various cations and anions has also been investigated. The detection limits for analyte ions by 3sigma were 2.6 microg L(-1) for lead, 1.5 microg L(-1) for gold, 2.1 microg L(-1) for palladium. The accuracy of the method was evaluated by the analysis of certified reference materials (NIST SRM 2711 Montana soil, GBW 07309 Stream sediment). The proposed procedure was successfully applied to environmental samples for the determinations of analytes.     

Development of a selective and sensitive flotation method for determination of trace amounts of cobalt, nickel, copper and iron in environmental samples

A simple, selective and rapid flotation method for the separation-preconcentration of trace amounts of cobalt, nickel, iron and copper ions using phenyl 2-pyridyl ketone oxime (PPKO) has been developed prior to their flame atomic absorption spectrometric determinations. The influence of pH, amount of PPKO as collector, type and amount of eluting agent, type and amount of surfactant as floating agent and ionic strength was evaluated on the recoveries of analytes. The influences of the concomitant ions on the recoveries of the analyte ions were also examined. The enrichment factor was 93. The detection limits based on 3 sigma for Cu, Ni, Co and Fe were 0.7, 0.7, 0.8, and 0.7 ng mL(-1), respectively. The method has been successfully applied for determination of trace amounts of ions in various real samples.     

Solidified floating organic drop microextraction (SFODME) for simultaneous separation/preconcentration and determination of cobalt and nickel by graphite furnace atomic absorption spectrometry (GFAAS)

Solidified floating organic drop microextraction (SFODME), combined with graphite furnace atomic absorption spectrometry (GFAAS) was proposed for simultaneous separation/enrichment and determination of trace amounts of nickel and cobalt in surface waters and sea water. 1-(2-Pyridylazo)-2-naphthol (PAN) was used as chelating agent. The main parameters affecting the performance of SFODME, such as pH, concentration of PAN, extraction time, stirring rate, extraction temperature, sample volume and nature of the solvent were optimized. Under the optimum experimental conditions, a good relative standard deviation for six determination of 20 ng l⁻¹ of Co(II) and Ni(II) were 4.6 and 3.6%, respectively. An enrichment factor of 502 and 497 and detection limits of 0.4 and 0.3 ng l⁻¹ for cobalt and nickel were obtained, respectively. The procedure was applied to tap water, well water, river water and sea water, and accuracy was assessed through the analysis of certified reference water or recovery experiments.     

Coprecipitation of Ni(2+), Cd(2+) and Pb(2+) for preconcentration in environmental samples prior to flame atomic absorption spectrometric determinations

A coprecipitation procedure has been presented prior to flame atomic absorption spectrometric determination of nickel, cadmium and lead ions in environmental samples. Analyte ions were coprecipitated by using copper hydroxide precipitate. The influences of some analytical parameters like amounts of copper, sample volume, etc., on the recoveries of the analytes were investigated. The interference of other ions was negligible. Under the optimized conditions, the detection limits (3 sigma, n=15) of lead(II), nickel(II) and cadmium(II) were 7.0, 3.0 and 2.0 microg/L, respectively. The proposed method has been successfully applied for the determination of traces of Ni, Cd and Pb in environmental samples like tap water.     

Multi-element coprecipitation for separation and enrichment of heavy metal ions for their flame atomic absorption spectrometric determinations

A preconcentration-separation technique for lead(II), cadmium(II), chromium(III), nickel(II) and manganese(II) ions has been established. The procedure is based on coprecipitation of these ions by the aid of Cu(II)-dibenzyldithiocarbamate precipitate. The precipitate was dissolved in 0.5 mL of concentrated HNO(3), and made up to 5 mL with distilled water. The heavy metals were determined by flame atomic absorption spectrometer. The effects of analytical parameters like pH, amounts of reagents, sample volume, etc. on the recoveries of heavy metals were investigated. The influences of matrix ions were also examined. The detection limits for the heavy metals based on 3 sigma (N=21) were found in the range of 0.34-0.87 microg L(-1). In order to validate the proposed method, two certified reference materials of NIST SRM 2711 Montana soil and NIST SRM 1515 Apple leaves were analyzed with satisfactory results. The proposed method was applied for the determination of lead, cadmium, chromium, nickel and manganese in environmental samples.     

Gadolinium hydroxide coprecipitation system for the separation-preconcentration of some heavy metals

A simple and new procedure for the determination of trace amounts of lead(II), cobalt(II), manganese(II) and copper(II) is described, that combines atomic absorption spectrometry-gadolinium hydroxide coprecipitation. One milliliter of 1% gadolinium(III) solution was added to each sample; the pH was then adjusted to 11 in order to collect trace heavy metals on gadolinium(III) hydroxide. The precipitate was separated by centrifugation and dissolved in 1 mL of 1 mol L(-1) HNO3. The influences of analytical parameters including amount of gadolinium(III), sample volume, etc. were investigated on the recoveries of analyte ions. The effects of concomitant ions were also examined. The recoveries of the analyte ions were greater than 95. The detection limits for the analyte elements based on 3 sigma (n=20) were in the range of 0.52-12.0 microg L(-1). The method was applied to the determination of analytes in real samples and good results were obtained (relative standard deviations <10%, recoveries >95%).     

Gas permeability of graphite foil modified with iron,cobalt, and nickel oxides

Graphite foils containing iron(III), cobalt(II), and nickel(II) oxides have been prepared via the impregnation of oxidized graphite in aqueous FeCl₃, Co(NO₃)₂, and Ni(NO₃)₂ solutions, followed by exfoliation via thermal shock and pressing of the resultant exfoliated graphite. The materials thus prepared have been characterized by X-ray diffraction, scanning electron microscopy, and energy dispersive X-ray spectroscopy. We have studied the gas transport properties of the modified graphite foil samples and observed a considerable increase in the nitrogen and hydrogen permeabilities of the metal oxide-modified graphite foils relative to the unmodified graphite foil. The thermal properties of the samples have been studied by thermogravimetry and differential scanning calorimetry. The results demonstrate that their oxidation onset temperature reaches 570°C.     

Sensitive and universal indirect chemiluminescence detection for capillary electrophoresis of cations using cobalt(II) as a probe ion

Highly sensitive and universal indirect chemiluminescence detection for capillary electrophoresis of cations was described. This novel method is based on use of the ultrasensitive cobalt(II) as a probe ion in the running buffer. A strong and stable background chemiluminescent signal can be generated by the luminol-hydrogen peroxide reaction catalyzed by cobalt(II) ion. Displacement of the cobalt(II) probe ion in the running buffer by a migrating sample cation results in a quantifiable decrease in the background signal. The conditions for electrophoresis and the chemiluminescent reaction were systematically investigated using a commercial capillary electrophoresis instrument with an in-house-built chemiluminescence detector. Under the optimal conditions, the detection limits of the concentration for manganese(II), cadmium(II), nickel(II), lead(II), and 14 lanthanides were (3.0-6.0) x 10(-9) mol/L (S/N = 3), which was approximately 3 orders of magnitude better than indirect UV detection and 2 orders better than indirect laser-induced fluorescent detection. A mixture of 18 metal ions including 14 lanthanides was efficiently separated within 3.5 min using lactate to partially complex the metal ions. Our data demonstrated that CE with indirect CL detection was a powerful and universal tool for analysis of inorganic and organic cations.     

Determination of trace lead in water samples by graphite furnace atomic absorption spectrometry after preconcentration with nanometer titanium dioxide immobilized on silica gel

Nanometer titanium dioxide immobilized on silica gel (immobilized nanometer TiO2) was prepared by sol-gel method and characterized using X-ray diffraction (XRD) and scanning electron microscope (SEM). The adsorptive capability of immobilized nanometer TiO2 for lead was assessed in this work using column method. It was found that lead can be quantitatively retained by immobilized nanometer TiO2 in the pH range 4-7, then eluted completely with 1.0molL(-1) HCl. The adsorption capacity of immobilized nanometer TiO2 for Pb was found to be 3.16mgg(-1). A new method has been developed for the determination of trace lead based on preconcentration with a microcolumn packed with immobilized nanometer TiO2 prior to its determination by graphite furnace atomic absorption spectrometry (GFAAS). The detection limit of this method for Pb was 9.5ngL(-1) with an enrichment factor of 50, and the relative standard deviations (R.S.D.s) was 3.2% at the 10ngmL(-1) Pb level. The method was validated using a certified reference material, and was applied for the determination of trace lead in water samples.     

4-(5-氯-2-吡啶)-偶氮-1,3-二氨基苯光度法测定电镀废水中的微量镍(Ⅱ)

4-(5-氯-2-吡啶)-偶氮-1,3-二氨基苯(5-Cl-PADAB)可与镍发生灵敏的显色反应,生成稳定的配位化合物。基于此建立了一种测定电镀废水中微量镍的光度法。结果表明:在2.0 mol/L HCl介质中,5-Cl-PADAB与Ni(Ⅱ)反应生成摩尔比2∶1的稳定配位化合物,其最大吸收波长为565 nm,表观摩尔吸光系数为6.42×104 L/(mol.cm),Ni(Ⅱ)含量在0～1.0 mg/L内符合比尔定律;该方法用于测定电镀废水中微量镍,结果与催化-分光光度法相符,相对标准偏差小于4.0%,加标回收率为98.5%～101.8%。     

Simultaneous determination of trace cadmium and arsenic in biological samples by hydride generation-double channel atomic fluorescence spectrometry

Hydride generation atomic fluorescence spectrometry (HG-AFS) has been used for determination of hydride-forming elements because of its high sensitivity, simplicity, and low costs, but most of such work has been concentrated on single element analysis, and reports dealing with multielement determination by HG-nondispersive (ND)AFS are rare. In this work, a sensitive HG-NDAFS method was developed for simultaneous determination of trace cadmium and arsenic in biological materials. The conditions for the generation of volatile cadmium and arsenic species from the reaction with KBH4 in aqueous solution were investigated using a double-channel AFS integrated with an intermittent flow reactor. Like thiourea and Co(II), ascorbic acid was found to significantly enhance the generation efficiency of volatile Cd and As species. The interferences of coexisting ions were evaluated. Under optimal conditions, the detection limits for Cd and As were determined to be 10 and 150 ng L(-1), respectively. The precision for 11 replicate determinations at the 1 microg L(-1) Cd level and the 10 microg L(-1) As level were 3.5 and 2.7% (RSD), respectively. The recoveries of spike analytes in the biological samples studied ranged from 94 to 109%. The proposed method was successfully applied to the simultaneous determination of Cd and As in a variety of biological samples.