Evaluation of vapor generation for the determination of nickel by inductively coupled plasma-atomic emission spectrometry

Volatile species of Ni were generated by merging acidified aqueous samples and sodium tetrahydroborate(III) in a continuous flow system. The gaseous analyte was subsequently introduced via a stream of Ar carrier into the inlet tube of the plasma torch. Inductively coupled plasma atomic emission spectrometry (ICP-AES) was used for detection. The operating conditions (chemical and physical parameters) and the concentrations of different acids were evaluated for the efficient generation of Ni vapor. The detection limit (3 sigma(blank)) was 1.8 ng mL(-1). The precision (RSD) of the determination was 4.2% at a level of 500 ng mL(-1) and 7.3% for 20 ng mL(-1) (n=10). The efficiency of the generation process was estimated to be 51%. The possible interfering effect of transition metals (Cd, Co, Cu, Cr, Fe, Mn, Zn), hydride forming elements (As, Ge, Pb, Sb, Se, Sn, Te), and Hg on Ni signal was examined. This study has demonstrated that Ni vapor generation is markedly free of interferences.     

Chemical vapour generation of transition metal volatile species for analytical purposes: determination of Zn by inductively coupled plasma-optical emission spectrometry

Volatile species of Zn were generated by merging acidified aqueous samples and sodium tetrahydroborate(III) solution in a continuous flow system. The gaseous analyte was subsequently introduced via a stream of Ar carrier into the inlet tube of the plasma torch. Inductively coupled plasma optical emission spectrometry (ICP-OES) was used for detection. The operating conditions (chemical and physical parameters) and the concentrations of different inorganic (hydrochloric, nitric) and organic acids (acetic, citric, oxalic, tartaric) were evaluated for the efficient generation of Zn vapour. A detection limit (3sigma(blank)) of 4.6 ng mL(-1) was achieved. The precision (RSD) of the determination was 6.9% at a level of 250 ng mL(-1) and 4.7% for 1000 ng mL(-1) (n = 10). The efficiency of the generation process was estimated to be close to 50% in HCl. The possible interferent effect of transition metals (Cd, Co, Cu, Cr, Fe, Mn, Ni), hydride forming elements (As, Ge, Pb, Sb, Se) and Hg on Zn signal was examined. The method was validated by the determination of Zn in a certified reference material (CRM), NIST 1643d trace elements in water.     

Preliminary results on the determination of ultratrace amounts of cadmium in tea samples using a flow injection on-line solid phase extraction separation and preconcentration technique to couple with a sequential injection hydride generation atomic fluorescence spectrometry

In this work, a method was developed for determination of ultra-trace levels of Cd in tea samples by atomic fluorescence spectrometry (AFS). A flow injection solid phase extraction (FI-SPE) separation and preconcentration technique, to on-line couple with a sequential injection hydride generation (SI-HG) technique is employed in this study. Cd was preconcentrated on the SPE column, which was made from a neutral extractant named Cyanex 923, while other matrix ions or interfering ions were completely or mostly separated off. Conditions for the SPE separation and preconcentration, as well as conditions for the HG technique, were studied. Due to the separation of interfering elements, Cd hydride generation efficiency could be greatly enhanced with the sole presence of Co²⁺ with a concentration of 200 μg L⁻¹, which is much lower than those in other works previously reported. Interferences on both the Cd separation and preconcentration, and Cd hydride generation (HG) were investigated; it showed that both the separation and preconcentration system, and the HG system had a strong anti-interference ability. The SPE column could be repeatedly used at least 400 times, a R.S.D. of 0.97% was obtained for 6 measurements of Cd with 0.2 μg L⁻¹ and a correlation coefficiency of 1.0000 was obtained for the measurement of a series of solutions with Cd concentrations from 0.1 to 2 μg L⁻¹. The method has a low detection limit of 10.8 ng L⁻¹ for a 25 mL solution and was successfully validated by using two tea standard reference materials (GBW08513 and GBW07605).     

Arsenic species analysis in freshwater using liquid chromatography combined to hydride generation atomic fluorescence spectrometry

A novel pretreatment system and method for arsenic species continuous analysis of arsenite, arsenate, monomethylarsenate (MMA) and dimethylarsonate (DMA) in freshwater using liquid chromatography combined to hydride generation atomic fluorescence spectrometry (LC-HG-AFS) was designed. Arsenic species of As(III), As(V), MMA and DMA in freshwater samples can be well separated, and the analytical time using the developed method is shortened twice compared to the conventional analytical procedure. Besides, the signal of As(V) can be increased by about 50% and the sensitivity to As(V) has been enhanced. The common coexisting ions in freshwater samples have no interferences with arsenic speciation analysis. A sensitive, low cost and interference-free procedure was developed and successfully applied to arsenic speciation in freshwater with the recoveries of four arsenic species within 89.2–106.2%. LC-HG-AFS has good prospects for speciation analysis of trace and ultra trace elements allowing for hydride generation.     

Spectroscopic and analytical characteristics of an inductively coupled argon plasma combined with hydride generation with or without simultaneous introduction of the sample aerosol for optical emission spectrometry

A radially viewed inductively coupled argon plasma was used for optical emission spectrometry of volatile species formed by reaction with NaBH₄ (hydride generation). The volatile hydrides were either introduced into the plasma alone or at the same time as a sample aerosol generated by pneumatic nebulization with a commercially available Concomitant Metals Analyzer. The effects of the forward power, the presence of pre-reducing agents [(NH₂)₂SC, KI, KBr and hot HCl], the occurrence of easily ionized elements (Ca, K, Mg and Na) in the analyte solutions on the excitation temperature (as measured via Ar atomic lines) and the electron number density were investigated for both of the sample introduction modes applied. The detection limits and the signal-to-background intensity ratios for As, Bi, Sb, Se and Sn lines were also evalutated and were observed to deteriorate with increasing power. When simultaneous hydride generation and pneumatic nebulization was employed under optimized experimental conditions, detection limits of 3.5, 2.9, 4.3, 1.5 and 2.1 μg L⁻¹ for As, Bi, Sb, Se and Sn, respectively, were obtained, and the intensities of the analytical lines for elements that do not form volatile hydrides were found to be 40% (Cd), 30% (Ni), 20% (Co, Cr, Fe, Mn and Zn) and 10% (Cu, Mg, V) greater than those obtained when only pneumatic nebulization was used.     

Determination of heavy metal traces in metallic materials with IDMS

Summary Two pure copper samples were analysed for Cr, Ni, Zn, Cd, and Pb with isotope dilution mass spectrometry (IDMS) as a part of a certification campaign of the European Community Bureau of Reference in Brussels. Additionally, one commercially available copper powder was determined for Zn, Cd, and Pb. After dissolution of the sample in aqua regia Pb was separated from the matrix by anodic electrodeposition, the other elements by anion-exchange chromatography. Positive thermal ions were produced in a single-filament ion source using the silica gel technique with phosphoric acid for Zn, Cd, and Pb and with boric acid for Cr and Ni. Most of the heavy metals could be determined with relative standard deviations of about 1% down to the ng/g level. The detection limits were 13 ng/g for Zn, 4 ng/g for Ni, 2 ng/g for Cr, 1 ng/g for Pb, and 0.03 ng/g for Cd. The results were compared with those obtained by another IDMS laboratory and by other methods applied during the certification campaign.

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Bestimmung von Schwermetallspuren in metallischen Werkstoffen mit der massenspektrometrischen IsotopenverdünnungsanalyseTeil 1. Bestimmung von Cr, Ni, Zn, Cd und Pb in reinem Kupfer

     

Applicability of ICP-OES,UV-VIS,and FT-IR Methods for the Analysis of Coffee Products

Spectroscopic methods were applied to study and compare the nutrient composition of ground, instant, and chicory coffee products. The total concentrations of 17 elements, including major (Ca, Mg, P) and trace (As, Ba, Cd, Co, Cr, Cu, Fe, Mn, Ni, Pb, Se, Sr, Ti, Zn) elements were determined in solid samples and infusions from ground coffee by means of inductively coupled plasma atomic optical spectrometry (ICP-OES). For measurement of As and Se levels, hydride generation technique (HG-ICP-OES) was used. The accuracy of the element measurements was verified by the analysis of certified reference materials (tea leaves (INCT-TL-1), apple leaves (1515), and TORT-2). Caffeine was determined by UV spectrometry. Infrared spectroscopy was applied to investigate organic matter of the coffees. Soluble oxalate was determined by a redox titration. Additionally, measurements of some physico-chemical parameters such as moisture, ash, pH, and starch (coffee adulteration) were performed. Differences in the composition of analyzed ground and instant coffees based on the contents of caffeine, oxalate, and minerals such as Cu, Mg, P, and Zn were found. FT-IR spectroscopy was a suitable tool to characterize the presence of caffeine and oxalate.     

Monitoring of Zn(II) and Cd(II) adsorption on activated carbon from aqueous multicomponent solutions by differential pulse polarography (DPP)

The adsorption process of Zn(II) and Cd(II) from aqueous solution has been investigated from both kinetic and equilibrium standpoints, using differential pulse polarography (DPP) on a mercury dropping electrode as the analytical technique. With such an aim, adsorption experiments were performed using not only a single metal ion–Zn(II) or Cd(II) solution but also a multi-component ion metal–Zn(II), Cd(II) and Hg(II) solution. The influence of the pH change in the multi-component ion metal solution on the adsorption of Zn(II) and Cd(II) was also studied. The adsorption processes is relatively fast for Zn(II) and Cd(II). The presence of two foreign ions in the solution slightly speeds up the adsorption process for Zn(II) and significantly slows it down for Cd(II). The adsorption isotherms are similarly shaped for Zn(II) and Cd(II). The addition of the foreign ions has a more unfavourable effect on the adsorption for Cd(II) than for Zn(II). At pH 2, neither Zn(II) nor Cd(II) is adsorbed practically on the carbon. The voltammetric approach has proved to be a fast and efficient method that, at the same time, enables one to monitor the adsorption of Zn(II) and Cd(II) with potential on-line application, which could be useful in waste-water treatment.     

Accumulation and voltammetric determination of complexed metal ions at zeolite-modified sensor electrodes

Chemically modified electrodes based on zeolite-containing graphite pastes were constructed and evaluated as sensor electrodes for the voltammetric determination of traces of metallic species in solution. Zeolite molecular sieves with pore sizes of 3, 4, 5, and 10 A were all suitable for chemical deposition and subsequent voltammetric quantitation of traces of Cu(II), Cd(II), and Zn(II). The highest sensitivity was obtained using the zeolite with the 10 A pore size. The detection limit obtained for Cu(II) was 0.3 muM following a 2 min chemical deposition. The detection limits for Cd(II) and Zn(II) following a 4 min chemical deposition were 87 nM and 145 nM, respectively. The effects on the zinc signal of coexisting metallic species in the ammonia deposition medium were studied. While the addition of Hg(II) gave rise to increasing zinc signals, the addition of Ag(I), Cu(II), Cd(II), Ni(II), and Co(II) resulted in decreasing zinc signal amplitudes. Most notably, the magnitude of the interference from these latter metal ions correlated well with the coordination numbers of their ammonia complexes. Thus the electrode acted as a device which was sensitive to the size and shape of the interfering metal complex.     

Simultaneous multi-element analysis of trace elements in soil samples by means of high-resolution inductively coupled plasma sector field mass spectrometry (SF-ICP-MS)

The potential of SF-ICP-MS for trace element analysis in complex environmental matrices such as soil solutions was investigated. Spectral interferences found in mass spectra of soil matrices are presented in detail. Furthermore, the influences of single components of the soil matrix on the signal intensity of selected elements were studied. Detection limits of different elements are presented with respect to the composition of the matrix. A fast and accurate method for quasi-simultaneous determination of Al, Si, P, V, Cr, Mn, Fe, Ni, Co, Cu, Zn, As, Se, Sr, Mo, Cd, Sn, Hg and Pb in aqueous soil extracts was established.     

Determination of Cu, Zn, Fe, Ni and Cd by flame atomic absorption spectrophotometry after preconcentration by Escherichia coli immobilized on sepiolite

A method for the determination of Cu, Zn, Fe, Ni and Cd by flame atomic absorption spectrophotometry (FAAS) after preconcentrating on a column containing Escherichia coli immobilized on sepiolite has been developed. Optimum pH values, amount of adsorbent, elution solution and flow rate have been obtained for the elements studied. The effect of interfering ions on the recovery of the analytes has also been investigated. Recoveries of Cu, Zn, Fe, Ni and Cd by E. coli immobilized on sepiolite were 99.1+/-0.6, 98.2+/-0.6, 98.1+/-0.5, 97.2+/-0.8 and 98.2+/-0.4% at 95% confidence level, respectively. The adsorption capacity of E. coli immobilized on sepiolite was found as 0.148, 0.064, 0.098, 0.134 and 0.088 mmol/g for Cu, Zn, Fe, Ni and Cd, respectively. The proposed method was applied to the determination of trace metals in alloys (NBS SRM 85b). Trace metals have been determined with relative error lower than 10%.     

A new Schiff base system bearing two naphthalene groups as fluorescent chemodosimeter for Zn2+ ion and its logic gate behavior

1-((E)-(2-((2-nitrobenzyl)(2-((E)-(2-hydroxynaphthalen-1-yl)methyleneamino)ethyl)amino)ethylimino)methyl)naphthalen-2-ol (H(2)L), The new compound featuring two naphthalene units was synthesized and characterized. We find that H(2)L has high selectivity and sensitivity to detect Zn(2+) ion over other metal ions such as Na(+), Ag(+), Cd(2+), Co(2+), Cr(3+), Cu(2+), Hg(2+), Mn(2+), Ni(2+), Fe(3+), and the sensitivity is about 10(-7)M. The fluorescent changes of H(2)L upon the addition of cations Zn(2+) and triethylamine is utilized as an AND logic gate at the molecular level, using Zn(2+) and triethylamine as chemical inputs and the fluorescence intensity signal as output.     

Dynamic adsorption and desorption of heavy metal ions on poly(acrylaminophosphonic-carboxyl-hydrazide) chelating fiber

The dynamic adsorption and desorption properties, including the effect of pH value and flow rate on the adsorption, eluent acidity and volume, eluting velocity and re-use, of Cu(II), Pb(II), Zn(II), Cd(II), Mn(II), Ni(II), Co(II) and Hg(II) ions on the column loaded with poly(acrylaminophosphonic-carboxyl-hydrazide) chelating fiber were investigated. The recovery of Mn(II), Co(II), Cd(II), Ni(II) and Zn(II) ions in the presence of Na, K, Ca and Mg ions was examined. The preconcentration of trace amounts of Mn(II), Co(II), Cd(II), Ni(II) and Zn(II) ions from model solution samples was carried out with satisfactory results. The amount of the metal ions detected after preconcentration and recovery by this technique was basically in agreement with the added amount. The method is rapid, precise and simple. Received: 15 October 1997 / Revised: 17 March 1998 / Accepted: 20 March 1998     

开链冠醚Schiff碱配体与过渡金属离子相互作用研究

合成了开链冠醚Schiff碱配体H₂L(H₂L=N,N′-双(邻羟苯亚甲基)-3,6-二氧杂-1,8-二氨基辛烷).详细研究了该配体在不同溶剂中和过渡金属离子存在下的荧光光谱,探讨了溶剂极性和不同金属离子对其荧光光谱的影响.结果表明:溶剂的极性和金属离子对其荧光性质有较大影响,随着溶剂极性的减小,配体的荧光增强,且谱峰发生蓝移.金属离子Zn²⁺、Cd²⁺对配体具有荧光增敏作用,Ni²⁺、Cu²⁺具有荧光猝灭作用.探讨了配体与金属离子结合的pH范围,结果显示最佳pH值为7—8.     

Dynamic adsorption and desorption of heavy metal ions on poly(acrylaminophosphonic-carboxyl-hydrazide) chelating fiber

The dynamic adsorption and desorption properties, including the effect of pH value and flow rate on the adsorption, eluent acidity and volume, eluting velocity and re-use, of Cu(II), Pb(II), Zn(II), Cd(II), Mn(II), Ni(II), Co(II) and Hg(II) ions on the column loaded with poly(acrylaminophosphonic-carboxyl-hydrazide) chelating fiber were investigated. The recovery of Mn(II), Co(II), Cd(II), Ni(II) and Zn(II) ions in the presence of Na, K, Ca and Mg ions was examined. The preconcentration of trace amounts of Mn(II), Co(II), Cd(II), Ni(II) and Zn(II) ions from model solution samples was carried out with satisfactory results. The amount of the metal ions detected after preconcentration and recovery by this technique was basically in agreement with the added amount. The method is rapid, precise and simple. Received: 15 October 1997 / Revised: 17 March 1998 / Accepted: 20 March 1998     

Senio river ecosystem: characterization and distribution of inorganic species in water and sediments

Analytical results are reported for the determination of inorganic species in water and sediments sampled in the Senio river ecosystem. The species determined are Cu, Pb, Cd, Zn, Co, Cr, Ni, Fe, Mn, Hg, F-, Cl-, Br, NO3-, SO4-, Na+, K+, Ca++, Mg++, NH4+ in integrated water, and Cu, Pb, Cd, Zn, Co, Cr, Ni, Fe, Mn, Hg in sediments. For all the elements, in addition to detection limits, precision and accuracy are given: the former, expressed as relative standard deviation (sr), and the latter, expressed as relative error (e), were good, being in all cases lower than 6%. Limitedly to Cu, Pb, Cd and Zn a critical comparison with voltammetric measurements is also discussed.     

识别过渡金属离子的1,8-萘二甲酰亚胺多胺衍生物荧光传感器的研究

A series of fluorescent chemosensors 1-3 were synthesized to detect transition metal ions. At the room temperature, fluorescence intensities of these chemosensors in acetonitrile without transition metal ions were found to be very weak, due to the process of the e±cient intramolecular photoinduced electron transfer (PET). However, after addition of the transition metal ions, the chemosensor 1-3 exhibits obvious fluorescence enhancement. Moreover, the intensity of the fluorescence emission of chemosensors increases significantly in the presence of Zn2+ and Cd2+. The fluorescent chemosensors with different polyamine as receptors show diverse a±nity abilities to the transition metal ions and signal the receptor-metal ion interaction by the intensity change of fluorescence emission.     

Multi-elemental analysis in biological samples by on-line preconcentration on 8-hydroxyquinoline-cellulose microcolumn coupled to simultaneous ICP-AES

Summary The analytical performance of an on-line oxine-cellulose microcolumn preconcentration system coupled to simultaneous ICP was investigated. Different factors including the pH of the sample solution, the flow rates of sample loading and eluation, the acidity of eluent and different eluents were investigated and optimized. In comparison with continuous aspiration, the signal enhancement factors of eleven elements (Zn, Cu, Ni, V, Cr, Fe, Mn, Co, Pb, Cd and Al) were in the range of 6.4 to 13.5 for peak height (0.5 s) and 3.7 to 5.8 for peak area (15 s), respectively. The influences of matrix ions, such as Ca, Mg, Fe, Cu and NaCl were studied. Performance was demonstrated by simultaneous determination of seven (Zn, Cu, Ni, V, Cr, Fe, Mn) elements in a number of CRMs. Most results were satisfactory, except for iron and chromium. The possible reasons were discussed. Co, Pb, Cd and Al were not available in the simultaneous instrument. Therefore, only the analytical performance was measured for these elements by the sequential instrument.On leave from Shanghai Institute of Metallurgy, Academia Sinica, Shanghai, China 200050     

Simultaneous multi-element analysis of trace elements in soil samples by means of high-resolution inductively coupled plasma sector field mass spectrometry (SF-ICP-MS)

The potential of SF-ICP-MS for trace element analysis in complex environmental matrices such as soil solutions was investigated. Spectral interferences found in mass spectra of soil matrices are presented in detail. Furthermore, the influences of single components of the soil matrix on the signal intensity of selected elements were studied. Detection limits of different elements are presented with respect to the composition of the matrix. A fast and accurate method for quasi-simultaneous determination of Al, Si, P, V, Cr, Mn, Fe, Ni, Co, Cu, Zn, As, Se, Sr, Mo, Cd, Sn, Hg and Pb in aqueous soil extracts was established. Received: 3 January 2000 / Revised: 28 March 2000 / Accepted: 31 March 2000     

Monitoring of inorganic species distribution in water and sediments of Aso river

Analytical results are reported for the determination of inorganic species in water and sediments sampled in the Aso river ecosystem. The species determined are Cd, Co, Cr, Cu, Fe, Mn, Ni, Zn, Hg, F-, NO3-, SO4--, Na, K, Ca, Mg, NH4+ in water, and Cd, Co, Cr, Cu, Fe, Mn, Ni, Zn, Hg in sediments. For all the elements, in addition to detection limits, precision and accuracy are given: the former, expressed as relative standard deviation (Sr), and the latter, expressed as relative error (e), were good, being in all cases lower than 6%.