Determination of four additives in aluminum electrolyte by ICP-OES with wet digestion

A method to quantify K, Ca, Mg and Li in aluminum electrolyte by ICP-OES with wet digestion was developed. The samples were digested using aqua regia in PTFE beakers and heated by electric hot plate. The levels of four additives, namely KF, CaF₂, MgF₂ and LiF in aluminum electrolyte were determined simultaneously by ICP-OES. The recovery rate of this method was 93.27%–103.51%. Accuracy was also proven through the measurement of standard sample of aluminum electrolyte. The developed method was applied to relative standard deviations for three digestion replicates of ten samples were in the range from 0.51% to 8.33%.     

Investigation of four digestion procedures for multi-element determination of toxic and nutrient elements in legumes by inductively coupled plasma-optical emission spectrometry

A simple and reliable multi-element procedure for determination of essential (Cr, Cu, Fe, Mg, Mn, Zn) and toxic (Al, Cd, Pb) elements in legumes by inductively coupled plasma-optical emission spectrometry (ICP-OES) was developed. In this contribution, four different digestion procedures were thoroughly investigated and accurately evaluated with respect to their affect on the analysis of legumes. These included wet digestion with HNO₃/H₂SO₄ and HNO₃/H₂SO₄/H₂O₂, and dry ashing with Mg(NO₃)₂ and Mg(NO₃)₂/HNO₃. Two calibrations (aqueous standard and standard addition) procedures were studied, and proved that standard addition was preferable for all analytes. ICP-OES operating parameters, such as radio-frequency (RF) incident power, sample uptake flow rate and nebulizer argon gas flow rate were optimized. The precision as repeatability, expressed as relative standard deviation (R.S.D.) for aqueous standard containing 250 μg l⁻¹ of each analyte was in the range1.5-8.0%. The accuracy, expressed as relative error was generally varied in the range of 0.5-10% for all analytes, while the quantification limits were lower than 2.5 μg g⁻¹. Although, acceptable results were obtained from all developed procedures, wet digestion method with HNO₃/H₂SO₄/H₂O₂ is recommended for better recovery. The good agreement between measured and certified concentrations with respect to IAEA-331 and IAEA-359 (CRM's supplied by IAEA, International Atomic Energy Agency) indicates that the developed analytical method is well suited for determination of toxic and nutrient elements in legumes and possibly similar matrices.     

ICP-OES法快速测定华阳川铀多金属矿中铌和铅

采用氢氟酸-硝酸-高氯酸体系对华阳川铀多金属矿进行高温消解,并对消解条件进行优化。使用电感耦合高频等离子体原子发射光谱仪(ICP-OES),在最佳仪器条件下,对华阳川铀多金属矿中铌元素和铅元素进行检测。结果表明,方法线性相关系数为分别为0.9998和0.9999,两种元素在标准样品中的加标回收率在96.0% ~104% 之间,平行样的相对标准偏差约0.50%~3.32%。实际样品加标回收率约为96.1 % ~ 102 %。该分析测试方法可以对华阳川铀多金属矿中铌铅元素进行快速、准确的测定。     

Use of fractional factorial design for optimization of digestion procedures followed by multi-element determination of essential and non-essential elements in nuts using ICP-OES technique

Two digestion procedures have been tested on nut samples for application in the determination of essential (Cr, Cu, Fe, Mg, Mn, Zn) and non-essential (Al, Ba, Cd, Pb) elements by inductively coupled plasma-optical emission spectrometry (ICP-OES). These included wet digestions with HNO₃/H₂SO₄ and HNO₃/H₂SO₄/H₂O₂. The later one is recommended for better analytes recoveries (relative error < 11%). Two calibrations (aqueous standard and standard addition) procedures were studied and proved that standard addition was preferable for all analytes. Experimental designs for seven factors (HNO₃, H₂SO₄ and H₂O₂ volumes, digestion time, pre-digestion time, temperature of the hot plate and sample weight) were used for optimization of sample digestion procedures. For this purpose Plackett-Burman fractional factorial design, which involve eight experiments was adopted. The factors HNO₃ and H₂O₂ volume, and the digestion time were found to be the most important parameters. The instrumental conditions were also optimized (using peanut matrix rather than aqueous standard solutions) considering radio-frequency (rf) incident power, nebulizer argon gas flow rate and sample uptake flow rate. The analytical performance, such as limits of detection (LOD < 0.74 μg g⁻¹), precision of the overall procedures (relative standard deviation between 2.0 and 8.2%) and accuracy (relative errors between 0.4 and 11%) were assessed statistically to evaluate the developed analytical procedures. The good agreement between measured and certified values for all analytes (relative error <11%) with respect to IAEA-331 (spinach leaves) and IAEA-359 (cabbage) indicates that the developed analytical method is well suited for further studies on the fate of major elements in nuts and possibly similar matrices.     

Application of ICP-OES to the determination of CuIn<Subscript>1−x</Subscript>Ga<Subscript>x</Subscript>Se<Subscript>2</Subscript> thin films used as absorber materials in solar cell devices

CuIn_1–xGa_xSe₂ [CIGS; x=Ga/(In+Ga)] thin films are among of the best candidates as absorber materials for solar cell applications. The material quality and main properties of the polycrystalline absorber layer are critically influenced by deviations in the stoichiometry, particularly in the Cu/(In+Ga) atomic ratio. In this work a simple, sensitive and accurate method has been developed for the quantitative determination of these thin films by inductively coupled plasma optical emission spectrometry (ICP-OES). The proposed method involves an acid digestion of the samples to achieve the complete solubilization of CIGS, followed by the analytical determination by ICP-OES. A digestion procedure with 50% HNO₃ alone or in the presence of 10% HCl was performed to dissolve those thin films deposited on glass or Mo-coated glass substrates, respectively. Two analytical lines were selected for each element (Cu 324.754 and 327.396 nm, Ga 294.364 and 417.206 nm, In 303.936 and 325.609 nm, Se 196.090 and 203.985 nm, and Mo 202.030 and 379.825 nm) and a study of spectral interferences was performed which showed them to be suitable, since they offered a high sensitivity and no significant inter-element interferences were detected. Detection limits for all elements at the selected lines were found to be appropriate for this kind of application, and the relative standard deviations were lower than 1.5% for all elements with the exception of Se (about 5%). The Cu/(In+Ga) atomic ratios obtained from the application of this method to CIGS thin films were consistent with the study of the structural and morphological properties by X-ray diffraction (XRD) and scanning electron microscopy (SEM).     

Determination of trace impurities in tantalum powder and its compounds by inductively coupled plasma optical emission spectrometry using solvent extraction

A procedure was developed for the analysis of 18 trace impurity elements in capacitor-grade tantalum powder (Ta), potassium tantalum fluoride (K₂TaF₇), and tantalum pentoxide (Ta₂O₅) using inductively coupled plasma optical emission spectrometry (ICP-OES). The detection limits achieved were in the ppb levels. The samples were dissolved in hydrofluoric acid (HF) in a microwave digestion system and the Ta matrix was extracted using cyclo hexanone. The impurity traces remained almost completely in the aqueous phase. The text was submitted by the authors in English.     

Preconcentration of trace aluminum (III) ion using a nanometer-sized TiO2-silica composite modified with 4-aminophenylarsonic acid, and its determination by ICP-OES

We describe a nanometer sized composite material made from titanium dioxide and silica that was chemically modified with 4-aminophenylarsonic acid and used for selective solid-phase extraction, separation and preconcentration of of aluminum(III) prior to its determination by ICP-OES. Under optimized conditions, the static adsorption capacity is 56.58?mg?g^?1, the enrichment factor is 150, the relative standard deviation is 1.6% (for n?=?11), and the detection limit (3?s) is 60?pg?mL^?1. The method was validated by analyzing the reference materials GBW 09101 (hair) and GBW 10024 (scallop) and successfully applied to the determination of trace Al(III) in spiked water samples and human urine, with recoveries ranging from 96% to 101%.

Determination of Arsenic,Cadmium, Cobalt,Chromium, Nickel,and Lead in Cosmetic Face-Powders: Optimization of Extraction and Validation

An analytical method for the quantification of toxic metals in face-powders is presented and discussed. Acid digestion with HNO₃-H₂O₂ or HNO₃-HCl was performed and compared with total digestion by HF. The digestion with HNO₃-H₂O₂ was the most suitable for these purposes. Analyses were performed by inductively coupled plasma atomic emission spectrometry (ICP-OES) and inductively coupled plasma mass spectrometry (ICP-MS), whose performances were compared by analyzing three different certified reference materials. The analysis of five commercial face-powders revealed the presence of all the considered metals in the range 0.06–8.0 µg/g. To simulate the bioaccessibility of metals in physiological conditions, a digestion with a simulated sweat solution was performed. In this case, the analysis of the same face-powder samples provided results below the limit of quantification, suggesting low bioaccessibility of the considered trace elements.     

Metal content in mosses from the Metropolitan Area of the Toluca Valley: a comparative study between inductively coupled plasma optical emission spectrometry (ICP-OES) and total reflection X-ray fluorescence spectrometry (TXRF)

The comparison between inductively coupled plasma optical emission spectrometry (ICP-OES) and total reflection X-ray fluorescence spectrometry (TXRF) for simultaneous determination of metal content (Cr, Cu, Fe, Mn, Pb and Zn) in mosses from the Metropolitan Area of the Toluca Valley was performed. Epiphytic mosses (Fabriona ciliaris and Leskea angustata) were collected in two sampling campaigns and were digested with HNO₃, HCl and HF for ICP-OES method and HNO₃ and HCl for TXRF method. The certified reference material (IAEA-336, Lichen) and the Standard Reference Material (SRM-1573, tomato leaves) were used for the quality control and to evaluate trueness and precision. Linearity, detection and quantification limits were also determined. Results show an ICP-OES and TXRF trueness mean of 101 ± 5% and 97 ± 9%, respectively; the relative standard deviation (RSD percent) was less than 17% in both methods. The moss samples exhibit a satisfactory precision (RSD ≤ 20%), because the RSD percent for ICP-OES, from 2% to 15%, and that for TXRF, from 1% to 17%, were obtained. One factor experimental design and simple regression analysis (α = 0.05) were used to compare the ICP-OES and TXRF metal concentrations. The statistical results do not show significantly different values for Cu, Mn, Pb and Zn in both the sample campaigns. In addition, the average results for Cr in the first sample campaign (30.3 ± 11.4 mg/kg for ICP-OES and 18.6 ± 9.8 mg/kg for TXRF) and Fe values in the second sample campaign (10,810 ± 2980 mg/kg for ICP-OES and 8380 ± 2350 mg/kg for TXRF) were significantly different in both methods. These differences are attributed to an incomplete sample digestion in the TXRF sample preparation. The results of the simple regression analyses show p-value less than 0.05, which indicates an equivalent and significant relation between ICP-OES and TXRF.     

Determination of trace impurities in high-purity zirconium dioxide by inductively coupled plasma atomic emission spectrometry using microwave-assisted digestion and wavelet transform-based correction procedure

This paper describes a rapid, accurate and precise method for the determination of trace Fe, Hf, Mn, Na, Si and Ti in high-purity zirconium dioxide (ZrO₂) powders by inductively coupled plasma atomic emission spectrometry (ICP-AES). The samples were dissolved by a microwave-assisted digestion system. Four different digestion programs with various reagents were tested. It was found that using a mixture of sulfuric acid (H₂SO₄) and ammonium sulfate ((NH₄)₂SO₄), the total sample dissolution time was 30 min, much shorter than that required for conventional digestion in an opening system. The determination of almost all of the target analytes suffered from spectral interferences, since Zr shows a line-rich atomic emission spectrometry. The wavelet transform (WT), a recently developed mathematical technique was applied to the correction of spectral interference, and more accurate and precise results were obtained, compared with traditional off-peak background correction procedure. Experimental work revealed that a high Zr concentration would result in a significant decrease in peak height of the analyte lines, which was corrected by standard addition method. The performance of the developed method was evaluated by using synthetic samples. The recoveries were in the range of 87-112% and relative standard deviation was within 1.1-3.4%. The detection limits (3σ) for Fe, Hf, Mn, Na, Si and Ti were found to be 1.2, 13.3, 1.0, 4.5, 5.8 and 2.0 μg g⁻¹, respectively. The results showed that with the microwave-assisted digestion and the WT correction, the detection limits have improved by a factor of about 5 for Fe, 4 for Mn and Ti, 3 for Si, and 2 for Hf and Na, respectively, in comparison with conventional open-system digestion and off-peak correction. The proposed technique was applied to the analysis of trace elements above-mentioned in three types of ZrO₂ powders.     

Determination of silicon in biological samples by ICP-OES after non-oxidative decomposition under alkaline conditions

A non-oxidative alkaline sample digestion procedure using tetramethylammonium hydroxide and a high pressure, microwave assisted autoclave digestion system was developed. The silicon concentrations of the digested samples were measured by inductively coupled axial plasma optical emission spectrometry (ICP-OES). Details of the digestion conditions as well as the optimised instrumental parameters for ICP-OES are described. The method was developed and tested using silicon-spiked ascorbic acid and applied to samples of animal tissue and organs. The total silicon content of two different reference materials, NIST 1577b Bovine liver and BCR 184 Bovine Muscle having neither certified nor informational values for Si was determined. The results obtained are compared with the results of independent methods such as wavelength dispersive x-ray fluorescence spectrometry (WDXRF) and solid sampling electrothermal atomic absorption spectrometry (ETAAS). The method described achieves a limit of detection of 2 mg kg^–1 using 100 mg of solid biological or organic material and covers a concentration range of up to 500 mg kg^–1. Received: 27 October 2000 / Revised: 31 January 2001 / Accepted: 2 February 2001     

Microwave enhanced alkaline digestion of silicate samples for determination of Fe2O3

A novel approach to the study of microwave enhanced alkaline digestion was developed for rapid digestion of silicate samples. By using alkali metal hydroxide solution as microwave digestion solvent, the feasibility and principle of digestion were discussed for the determination of Fe₂O₃ contents in quartz, kaolin, feldspar and soda-lime-silica glass. The results obtained from four standard samples and six real world samples are in good agreement with the certified values, and are comparable to the predicted results from traditional alkaline digestion method. All the above demonstrates that this new proposed method is precise, accurate and can provide a simple, fast and energy saving procedure for the determination of components in silicate samples.     

Imprinted Polymer Particles for Aluminum Uptake: Synthesis and Analytical Applications

This work reports the preparation of molecularly imprinted polymer (MIP) particles for selective extraction and determination of aluminum ion from aqueous media. Polymerization was achieved in a glass tube containing AlCl₃, morin, 4-vinylpyridine, ethyleneglycoldimethacrylate, 2,2′ - azobisisobutyronitrile. The polymer block obtained was ground and sieved (55–75 μ m) and the Al (III)-morin complex was removed from polymer particles by leaching with 2 M of HCl, which leaves a cavity in the polymer particles. The polymer particles, both prior to and after leaching, have been characterized by IR and differential scanning calorimetry (DSC) studies. The effect of different parameters, such as pH, adsorption and desorption time, type and least amount of eluent for elution of complex from polymer were evaluated. Extraction efficiencies more than 99% were obtained by elution of the polymers with 15 mL of methanol-acetonitrile mixture (1:2) followed by ICP-OES. The limit of detection of the proposed method was 3.5 μ g L^?1. A dynamic linear range (DLR) in the range of 20 to 200 μ g L^?1 was obtained. The relative standard deviation (RSD) was less than 6.5%. The influence of various cationic and anionic interferences on percent recovery of complex was studied. The method was applied to the recovery and determination of aluminum in different real samples.     

On-line solid phase extraction coupled to ICP-OES for simultaneous preconcentration and determination of some transition elements

An on-line solid phase extraction method coupled to ICP-OES was developed for the simultaneous determination of Ce(III), La(III), Sm(III), Y(III), Yb(III), Dy(III), Hf(IV), Zr(IV) and Th(IV) ions in aqueous samples. The ions forming hydrophobic complexes with 3,5,7,2?,4?-pentahydroxy flavone (morin) and were retained on an octadecyl silica (C₁₈) minicolumn. The adsorbed chelates were subsequently eluted from the column and directly transferred into the plasma with 80% (v/v) propanol:H₂O solution for the simultaneous determination of the metal ions. Different parameters affecting the ICP-OES signal intensities and extraction efficiency including pH of the solution, concentration of the chelating agent, flow rate and type of the eluent, loading rate and ionic strength were evaluated and optimized. The calibration graphs were linear in the range of 0.2–100 μg L^?1 and limit of detections for the extraction and determination of the ions in the aqueous sample (25 mL) were in the range 0.10–0.46 μg L^?1. The enhancement factors of the method for the metal ions obtained were in the range of 23 to 242 (V _Sample?=?25 mL) and the precision expressed as relative standard deviations (RSD %) was below 6.9%. Finally, the method was successfully applied to determine the target analytes in natural water samples.     

A simple chemiluminescence method for determination of chemical oxygen demand values in water

In this paper, a low cost chemiluminescence detector with a photodiode instead of photo-multiplier tube (PMT) was developed for environmental monitoring of water quality. Based on the chemiluminescent reaction of luminol-H₂O₂-Cr³⁺ system, light emission caused by luminol-H₂O₂-Cr³⁺ system was detected by the photodiode, and its intensity caused by the appearance of Cr³⁺ after samples digestion was proportional to the chemical oxygen demand (COD). Effects for COD determining such as pH, concentrations, interference, and digestion procedures were investigated. The experimental results show that this suggested method uses an instrument that is simpler and cheaper than the previous ones used for the same purpose. The data obtained by the present method were fairly in good agreement with those obtained by the standard reflux titrimetric method. It has been applied to determine real samples with satisfactory results.     

Selective ion exchange separation of uranium from concomitant impurities in uranium materials and subsequent determination of the impurities by ICP-OES

An ion exchange method has been developed for the separation of uranium from trace level metallic impurities prior to their determination by inductively coupled plasma optical emission spectrometry (ICP-OES) in uranium materials. Selective separation of uranium from trace level metallic impurities consisting Cr, Co, Cu, Fe, Mn, Cd, Gd, Dy, Ni, and Ca was achieved on anion exchange resin Dowex 1 × 8 in sulphate medium. The resin (100–200 mesh, in chloride form) was packed in a small Teflon column (7.8 cm × 0.8 cm I.D.) and brought into sulphate form by passing 0.2 N ammonium sulphate solution. Optimum experimental conditions including pH and concentration of sulphate in the liquid phase were investigated for the effective uptake of uranium by the column. Uranium was selectively retained on the column as anionic complex with sulphate, while impurities were passed through the column. Post column solution was collected and analyzed by ICP-OES for the determination of metallic impurities. Up to 2,500 μg/mL of uranium was retained with >99% efficiency after passing 25 mL sample through the column at pH 3. Percentage recoveries obtained for most of the metallic impurities were >95% with relative standard deviations <5%. The method established was applied for the determination of gadolinium in urania–gadolinia (UO₂–Gd₂O₃) ceramic nuclear fuel and excellent results were achieved. Solvent extraction method using tributylphosphate (TBP) as extractant was also applied for the separation of uranium in urania–gadolinia nuclear fuel samples prior to the determination of gadolinium by ICP-OES. The results obtained with the present method were found very comparable with those of the solvent extraction method.     

微波消解-电感耦合等离子体原子发射光谱法测定钼铁合金中的钼含量

采用电感耦合等离子体原子发射光谱法（ICP-OES）测定钼铁合金试样（钼质量分数为55%～65%）中的钼含量,单点校准获得了较好的线性.样品经酸化后微波消解处理,采用钇元素作为内标以减少仪器波动的影响,在波长202.030 nm的分析谱线处测得钼元素的最佳发射强度.检测结果显示微波消解的样品溶解时间可缩短为重量法的14%,检测结果的相对标准偏差为0.17%～0.22%,采用标准样品验证结果的准确度与重量法无显著差异,可以为ICP-OES法检测高含量组分提供参考.     

Effect of simultaneous cooling on microwave-assisted wet digestion of biological samples with diluted nitric acid and O2 pressure

The present work evaluates the influence of vessel cooling simultaneously to microwave-assisted digestion performed in a closed system with diluted HNO₃ under O₂ pressure. The effect of outside air flow-rates (60–190 m³ h⁻¹) used for cooling of digestion vessels was evaluated. An improvement in digestion efficiency caused by the reduction of HNO₃ partial pressure was observed when using higher air flow-rate (190 m³ h⁻¹), decreasing the residual carbon content for whole milk powder from 21.7 to 9.3% (lowest and highest air flow-rate, respectively). The use of high air flow-rate outside the digestion vessel resulted in a higher temperature gradient between liquid and gas phases inside the digestion vessel and improved the efficiency of sample digestion. Since a more pronounced temperature gradient was obtained, it contributed for increasing the condensation rate and thus allowed a reduction in the HNO₃ partial pressure of the digestion vessel, which improved the regeneration of HNO₃. An air flow-rate of 190 m³ h⁻¹ was selected for digestion of animal fat, bovine liver, ground soybean, non fat milk powder, oregano leaves, potato starch and whole milk powder samples, and a standard reference material of apple leaves (NIST 1515), bovine liver (NIST 1577) and whole milk powder (NIST 8435) for further metals determination by inductively coupled plasma atomic emission spectroscopy (ICP-OES). Results were in agreement with certified values and no interferences caused by matrix effects during the determination step were observed.     

电感耦合等离子体原子发射光谱(ICP-OES)法测定铝合金中微量的钆、镧、钕、镨、钐

研究了电感耦合等离子体发射光谱(ICP-OES)法测定6系铝合金中微量的钆、镧、钕、镨、钐的方法,优化了ICP-OES工作条件,用标准加入法和标准曲线法做了比较,测定微量含量时,标准加入法比标准曲线法准确,在定量限和检出限之间约5倍空白标准偏差(5σ)含量时,标准加入法的加标回收率在80%~112%,检测结果具有参考价值.     

Determination of arsenic,selenium and mercury in an estuarine sediment standard reference material using flow injection and atomic absorption spectrometry

A flow-injection analysis atomic absorption spectrometric (FIA-AAS) method was developed for the determination of trace amounts of arsenic, selenium and mercury in a proposed estuarine sediment standard reference material (SRM 1646a). The samples were prepared in two manners: a) A wet digestion procedure with HNO₃, H₂SO₄, and HClO₄ using a reflux column and b) A microwave-oven digestion procedure utilizing HNO₃, H₂SO₄, and HCl for As and Se, and HNO₃ for Hg. Microwave-oven digestion provides results comparable to those found by reflux column digestion and reduces the sample preparation time by a factor of 10. The proposed method employing the microwave-oven digestion procedure coupled with FIA-AAS for As and Se, and FIA-CVAAS for Hg, has detection limits of 0.15 ng As/ml, O.17 ng Se/ml and 0.15 ng Hg/ml.On leave from the Defense Metallurgical Research Laboratory, Hyderabad, India