Analysis of nickel-niobium alloys by inductively coupled plasma optical emission spectrometry

Inductively coupled plasma optical emission spectrometry (ICP-OES) was applied to the analysis of major and minor elements of Ni-Nb alloys obtained by aluminothermic reduction process. Digestion of samples was made using a mixture of HF+HNO₃. Minor and trace elements were determined without matrix separation. The precision for all constituents was <3%. Recoveries for the analyte-spiked samples were 95%.     

Multivariate optimization by exploratory analysis applied to the determination of microelements in fruit juice by inductively coupled plasma optical emission spectrometry

A method for the direct determination (without sample pre-digestion) of microelements in fruit juice by inductively coupled plasma optical emission spectrometry has been developed. The method has been optimized by a 2³ factorial design, which evaluated the plasma conditions (nebulization gas flow rate, applied power, and sample flow rate). A 1:1 diluted juice sample with 2% HNO₃ (Tetra Packed, peach flavor) and spiked with 0.5 mg L^− 1 of Al, Ba, Cd, Co, Cr, Cu, Fe, Mn, Ni, Pb, Sb, Sn, and Zn was employed in the optimization. The results of the factorial design were evaluated by exploratory analysis (Hierarchical Cluster Analysis, HCA, and Principal Component Analysis, PCA) to determine the optimum analytical conditions for all elements. Central point condition differentiation (0.75 L min^− 1, 1.3 kW, and 1.25 mL min^− 1) was observed for both methods, Principal Component Analysis and Hierarchical Cluster Analysis, with higher analytical signal values, suggesting that these are the optimal analytical conditions. F and t-student tests were used to compare the slopes of the calibration curves for aqueous and matrix-matched standards. No significant differences were observed at 95% confidence level. The correlation coefficient was higher than 0.99 for all the elements evaluated. The limits of quantification were: Al 253, Cu 3.6, Fe 84, Mn 0.4, Zn 71, Ni 67, Cd 69, Pb 129, Sn 206, Cr 79, Co 24, and Ba 2.1 µg L^− 1. The spiking experiments with fruit juice samples resulted in recoveries between 80 and 120%, except for Co and Sn. Al, Cd, Pb, Sn and Cr could not be quantified in any of the samples investigated. The method was applied to the determination of several elements in fruit juice samples commercialized in Brazil.     

Classification of Antarctic algae by applying Kohonen neural network with 14 elements determined by inductively coupled plasma optical emission spectrometry

Optical emission spectrometers can generate results, which sometimes are not easy to interpret, mainly when the analyses involve classifications. To make simultaneous data interpretation possible, the Kohonen neural network is used to classify different Antarctic algae according to their taxonomic groups from the determination of 14 analytes. The Kohonen neural network architecture used was 5×5 neurons, thus reducing 14-dimension input data to two-dimensional space. The input data were 14 analytes (As, Co, Cu, Fe, Mn, Sr, Zn, Cd, Cr, Mo, Ni, Pb, Se, V) with their concentrations, determined by inductively coupled plasma optical emission spectrometry in 11 different species of algae. Three taxonomic groups (Rhodophyta, Phaeophyta and Cholorophyta) can be differentiated and classified through only their Cu content.     

Plasma diagnostic on a low-flow plasma for inductively coupled plasma optical emission spectrometry

In order to elucidate the fundamental properties of a low-flow inductively coupled plasma (ICP) operated under total Ar consumption of 0.6 L min^− 1, excitation temperatures, rotational temperatures, ionization temperatures, electron temperatures, and electron number densities were studied with optical emission based methods. The plasma was operated in the SHIP torch (Static High Sensitivity ICP), which was designed for optical emission spectrometric detection.     

Practical implementation of survey analysis in inductively coupled plasma optical emission spectrometry

The combination of an echelle/charge coupled device detector based spectrometer with software for multicomponent analysis (MCA) allows practical implementation of survey analysis in inductively coupled plasma-optical emission spectrometry (ICP-OES). MCA requires models for the pure components. A procedure is described for how to obtain the models for 67 pure elements detectable in ICP-OES. In fact, each element is represented by two model vectors. Measurements at low analyte concentration provide the sensitivities for the prominent lines used in trace analysis, whereas weak lines and continuum emission are modelled with high concentration measurements. This modelling allows proper calibration for trace and major levels, and strongly reduces noise contributions. The model library is prepared once and a monitor solution, containing seven specific elements, is used to achieve a daily link with this once-only calibration (wavelength axis and sensitivity). To control the efficiency of atomization and ionization the Cr ii 267 nm to Cr i 357 nm ratio is used. The MCA calculations are repeated at different intensity levels in order to cover the dynamic range in intensity and, hence, concentration for all the elements present in the sample solution. Matrix-matching of the monitor solution was studied in order to overcome matrix effects owing to high acid or salt contents. Some certified reference materials were analysed. The results for most elements are found within 20% of the certified values.     

Determination of inorganic contaminants in glue by inductively coupled argon plasma optical emission spectrometry

A closed vessel method using a microwave oven was developed for the determination of As, B, Ba, Bi, Cd, Cr, Cu, Fe, Hg, Ni, Pb, Se, Sn and Sb by Inductively Coupled Argon Plasma Optical Emission Spectrometry (ICP OES). The method was applied to samples of polyvinyl acetate-based glue in water emulsions. Parameters such as wavelength, nebulization pressure and RF power were optimized and the residual acidity after the digestion process was determined. The addition of internal standards was evaluated and the accuracy of the proposed method was verified with addition and recovery experiments and also with certified reference materials, achieving good results. Using a nebulization flow rate of 0.73 L min⁻¹and a RF power of 1200 W it was possible to obtain adequate values for limit of detection and limit of quantification as well as recovery values in the range of 80-106%, for all the analytes. The analysis of coloured glue samples (white, black, blue, yellow, red and green), widely used by children, showed no contamination by the elements studied.     

电感耦合等离子体发射光谱法测定铜阳极泥中的金含量

实验采用某铜冶炼生产企业的铜阳极泥样品,对其中的金含量进行测试。用王水溶解样品,在3%王水酸度下,定容至100mL容量瓶,用电感耦合等离子体发射光谱法测定。经试验研究,选择242.795nm为分析谱线,方法检出限为(n=11)0.09μg/mL,测定下限为0.27μg/mL,加标回收率在97%-107%之间,线性相关系数为：0.999928,分析结果满足要求。     

Combined effects of inorganic acids in inductively coupled plasma optical emission spectrometry

The acid interferences in inductively coupled plasma atomic emission spectrometry (ICP OES) were studied in a multivariate way, considering the simultaneous presence of four mineral acids (hydrochloric, nitric, sulfuric and perchloric acid) with their concentrations ranging from 5 to 80% (w/w). A low power ICP OES was used, after optimization of operating parameters in order to achieve both plasma robustness and maximum signal to background ratios, favorable for trace element determinations in real samples. In order to investigate the interference mechanism, the combined effects of mineral acids on several parameters (solvent transport rate, analyte transport rate, excitation temperature, electron number density and magnesium ionic to atomic line intensity ratio) were evaluated and discussed. It was found that the combined effects of inorganic acids in ICP OES are, in general terms, more complex than the simple addition of the single effects. The more relevant interactions are between hydrochloric and nitric acids and those with sulfuric acid. Owing to these interactions, the resulting effects on the analytical signals are lower than the expected ones. The extent of any interaction depend on the nature of the interference. For the physical effects which are related with a change in the viscosity of the solution, an attenuation of the acid effect due to the presence of another acid at high concentration was evident. On the contrary, for the interferences related with a change in the plasma excitation conditions, the combined effects are higher than the addition of the single ones.     

Analysis of cement slurries by inductively coupled plasma optical emission spectrometry with axial viewing

The feasibility of Portland cement analysis by introduction of slurries in an inductively coupled plasma optical emission spectrometer (ICP-OES) with axial viewing has been evaluated. After a fast manual grinding of the cement samples, owing to the pulverized state of this material, 0.1% m/v slurries were prepared in 1% v/v HCl. The calibration was performed adopting two strategies: one based on slurries prepared from different masses (50, 75, 100 and 125 mg) of a Portland cement standard reference material (NIST SRM 1881), and the other one based on aqueous reference solutions. A complete analysis of cement for major (Al, Ca, Fe, Mg and Si), minor and trace elements (Mn, P, S, Sr and Ti) was accomplished. Both strategies led to accurate results for commercial Portland cement samples, except for Si and Ti, for which the calibration with aqueous reference solutions resulted in low values. Applying a paired t-test it was shown that most results were in agreement at a 95% confidence level with a conventional fusion decomposition procedure. The ICP-OES with axial viewing and end-on gas configuration for removal of the recombination plasma zone was effective for cement slurry analysis without any undesirable particle deposition in the pre-optics interface and without severe spectral interferences.     

Determination of trace elements in plant materials by inductively coupled plasma optical emission spectrometry

The use of inductively coupled plasmas as spectrometric emission sources for the determination of Fe, Mn, Cu, Al, B and Zn in orchard leaves is investigated. The plasma is shown to be sufficiently sensitive for the direct determination of all of the above elements in solutions of the plant materials after a dry ashing procedure. Comparative values for the trace element concentrations by other analytical methods are given.     

A practical approach to non-spectral interferences elimination in inductively coupled plasma optical emission spectrometry

Matrix effects and practical possibilities of reducing accompanying non-spectral interferences in inductively coupled plasma optical emission spectrometry (ICP-OES) were studied for microconcentric Micromist, concentric and V-groove nebulizers (VGN) coupled with two cyclonic spray chambers of different sizes. The effect of a wide scale of interferents and mixtures thereof in the concentration range of up to 2 mass % (Na, Ca, Ba, La, urea) or up to 20 vol. % (nitric acid) on the analysis of Cd, Cu, K, Mg, Mn, Pb and Zn was investigated in terms of their analytical recovery and Mg(II) 280.27 nm/Mg(I) 285.29 nm line intensity ratio. Recoveries of ionic lines were lower than those of atomic lines (37–102 %) depending on the matrix concentration. The Mg(II)/Mg(I) ratios were found to be 12–15 and they slightly decreased as the matrix load increased. Exceptional behavior of pure La matrix, steeply lowering the recoveries and Mg(II)/Mg(I) ratios was observed. A Micromist nebulizer coupled with a small inner volume spray chamber provided the highest recoveries (94–102 %), lowest matrix effects across the matrix loads and, compared to others, the least significant dependence without worsening of the analytical characteristics (recoveries, signal background ratios and the Mg(II)/Mg(I) ratios) across the studied matrices.     

Determination of titanium dioxide in foods using inductively coupled plasma optical emission spectrometry

Titanium dioxide is a common food additive of increasing interest in dietary intake studies and dietary exclusion studies. Food labelling for titanium dioxide is imprecise so a method was developed for its rapid determination in foods using acid digestion and inductively coupled plasma optical emission spectrometry (ICPOES). Twenty-five foods thought to contain titanium dioxide were obtained. Based on preliminary digestion studies, samples (500 mg) were digested in 18 mol l-1 H2SO4 at 250 degrees C for 1 h and then diluted to 5.9 mol l-1 H2SO4 before determination of titanium by ICPOES at 336.121 nm. Emission intensity was suppressed by H2SO4 so standards were matched for acid concentration. Titanium dioxide embedded in gelatine was used to assess accuracy. A standard reference material of known titanium concentration and six foods of known titanium dioxide content were used as external reference materials. Limits of detection were 2-7.5 ppb, depending on spectral integration times, and the signal was linear up to 5 ppm. Results for all control samples were in good agreement with the expected values. Twelve of the foods contained detectable titanium, ranging from 0.001 to 0.782% by weight, but only eight indicated this on their labels, four being exempt under food labelling regulations. Based on food portion sizes, an individual's daily intake of titanium dioxide could exceed 200 mg from just one of these products. This method may facilitate future studies on titanium dioxide intake, given the present limitations of food labelling.     

Oxygen bomb combustion of biological samples for inductively coupled plasma optical emission spectrometry

A rapid sample preparation method is proposed for decomposition of milk powder, corn bran, bovine and fish tissues, containing certified contents of the analytes. The procedure involves sample combustion in a commercial stainless steel oxygen bomb operating at 25 bar. Most of the samples were decomposed within 5 min. Diluted nitric acid or water-soluble tertiary amines 10% v/v were used as absorption solutions. Calcium, Cu, K, Mg, Na, P, S and Zn were recovered with the bomb washings and determined by inductively coupled plasma optical emission spectrometry (ICP-OES). Ethanol mixed with paraffin was used as a combustion aid to allow complete combustion. A cooling step prior releasing of the bomb valve was employed to increase the efficiency of sample combustion. Iodine was also determined in milk samples spiked with potassium iodide to evaluate the volatilization and collection of iodine in amine CFA-C medium and the feasibility of its determination by ICP-OES with axial view configuration. Most of the element recoveries in the samples were between 91 and 105% and the certified and found contents exhibited a fair agreement at a 95% confidence level.     

Improving the analytical performances of inductively coupled plasma optical emission spectrometry by multivariate analysis techniques

The various multivariate analysis techniques which have been successfully applied to maximize the analytical performance of ICP-OES are reviewed. These include optimization procedures, spectral data processing and calibration methods as well as classification and pattern recognition techniques.     

Direct inductively coupled plasma optical emission spectrometry for analysis of waste samarium-cobalt magnets

An analytical procedure for direct determination of Al, Mg, Ti, Cr, Mn, Nb, La, Nd, Eu, Gd, Tb, Dy, Tm, Yb, Lu, Hf, Ni, Cu, Fe, Zr Sm and Co by ICP-OES in waste samarium-cobalt magnets has been developed. The significant influence of the matrix on all determinable components has been shown. The influence of operation parameters (ICP power and nebuliser flow rate) on the matrix effect has been studied using two plasma observation modes (axial and radial). For the first time, the optimal conditions for ICP-OES analysis of waste samarium-cobalt magnets has been substantiated (ICP power 1400 W, nebuliser flow rate 0.5–0.6 L/min). The analytical capabilities of the method have been evaluated using spike recovery test, certified reference materials and comparison with ICP-MS. ICP-OES measurements were performed in the axial mode for trace elements (with concentrations of n·10^?4-n·10^?2 % wt.) and in the radial mode for matrix elements and analytes (with concentrations higher than n·10^?2 % wt.). The limits of quantification (LOQs) were in the range of n·10^?5 wt% for Mn, Zr and Yb and n·10^?4 wt% for Al, Mg, Ti, Cr, Hf, La, Ni, Cu, Tb, Lu, Nb, Fe, Nd, Eu, Gd, Dy and Tm. RSD ranged from 0.2 to 10.6%.     

Real-time internal standardization with an axially-viewed inductively coupled plasma for optical emission spectrometry

An evaluation of precision improvements using real-time internal standardization with an axially-viewed inductively coupled plasma (ICP) is presented. New findings are presented with respect to the nature of the noise in the analytical signals from the axial ICP. It is observed that a high degree of correlation exists in the line signals from the axial ICP. Using the yttrium ion line at 371.030 nm as the internal standard, the analytical precision after the application of real-time internal standardization is maintained between 0.1 and 0.2% relative standard deviation (RSD) for ion lines. Precision improvement factors of 3 to 4 are obtained by comparison with the uncorrected results. With atomic lines, real-time internal standardization using the yttrium ion line is less effective, yielding precision values between 0.2 and 0.7% RSD. The precision improvement factors for atomic lines are between 1.5 and 3. Thus, real-time internal standardization provides significant improvements in the RSDs of the line signals. The limits of these improvements are explored and an equation is presented which yields the fundamental shot noise limit for precision. Shot noise limited precision is demonstrated. However, this is not possible for all elements using a single internal standard signal. The effectiveness of real-time internal standardization is shown to be dependent on the nature of the specific spectral line. With the axially-viewed ICP, the dominant phenomenon preventing the full benefit of internal standardization from being obtained is the amplitude of the noise in the line signals and not the degree of correlation between analyte and internal standard signals. A trend is observed for atomic transitions in which lower excitation energy is correlated with higher relative noise amplitudes. This finding is in contrast with previously published work on the radially-viewed ICP. An explanation of this result is proposed which takes into account the influence of vaporizing sample droplets in the observation volume.     

Multivariate optimization of mercury determination by flow injection-cold vapor generation-inductively coupled plasma optical emission spectrometry

In this work a procedure for mercury determination by Flow Injection-Cold Vapor Generation-Inductively Coupled Plasma Optical Emission Spectrometry (FI-CVG-ICP OES) has been developed. The system uses a small homemade glass separator constructed to drive the Hg vapor to the plasma. An evolutionary operation factorial design was used to evaluate the optimal experimental conditions for mercury vapor generation, aiming at the low consumption of reagents, the improvement of the analytical signal and consequently greater sensitivity. The procedure allowed the determination of mercury and showed excellent linearity for the concentration range from 0.50 μg L(-1) to 100.0 μg L(-1), with Limits of Detection (LOD) and Quantification (LOQ) of 0.11 μg L(-1) and 0.36 μg L(-1), respectively, and a sampling rate of 36 analyses per hour. The optimized procedure showed good accuracy and precision, and the method was validated by the analysis of two certified reference materials: Buffalo River Sediment (NIST 2704) and human hair (IAEA 085). A good agreement with the certified values was achieved, with recovery values of 99% and 98% and relative standard deviation close to 2%.     

电感耦合等离子体质谱法测定烟酰胺药物元素杂质

建立了烟酰胺药物中30种元素杂质的ICP-MS分析方法,并根据USP< 233>进行了验证,在优化的实验条件下,本方法的检出限在4.0×10-4～0.4μg/L之间,加标回收率在86.3％～116.0％之间,与ICP-OES检测结果基本一致.用所建立方法对烟酰胺以及稳定性样品进行了元素杂质检测,根据样品制备工艺初步判断元素杂质的来源.