Kalman滤波技术校正电感耦合等离子体原子发射光谱分析中严重重叠的谱线干扰

针对ICP-AES中严重重叠谱线干扰的校正,研究了若干因素对Kalman滤波器性能的影响.减小扫描步长可以增强Kalman滤波法解析重叠谱线的能力.当重叠线对轮廓基本相同且扫描窗口内干扰元素只有一条谱线时,Kalman滤波法能分辨的重叠线对的最小峰间距为扫描步长的2～3倍.扫描窗口内较多的干扰元素谱线和重叠线对轮廓的显著差异有利于Kalman滤波器正确识别分析信号和干扰信号,可以利用这两个因素有效地分辨峰间距很小甚至完全重叠的谱线.     

电感耦合等离子体原子发射光谱法中Kalman滤波法解析重叠谱线的研究

考察了Kalman滤波技术校正ICP-AES中谱线重叠干扰的潜力。以新息序列的平均平方和为评价函数优化扫描光谱的峰位, 消除扫描过程中可能产生的波长定位误差, 从而保证滤波结果的准确性, 并使实际检出限显著改善。在中等分辨率光谱仪和扫描步长为1.5pm的条件下, 滤波器能有效地分辨峰间距只有4.8pm且峰形基本相同的重叠线对。对峰间距为9.8pm的重叠线时, 当线背比低至0.05左右时仍能获得满意结果。连续背景用理论描述, 因而样品溶液和纯组分溶液的光谱扫描无需扣除溶剂空白。     

自模型曲线分辨法校正电感耦合等离子体原子发射光谱中严重谱线重叠干扰

对严重重叠的光谱干扰校正,采用较小间隔的光谱扫描测量,并用间隔扫描点的数据计算,可减小计算结果的误差,提高结果的准确性。本方法用于校正Nd359.259nm对Sm359.260nm和V328.939nm对Yb328.937nm谱线重叠干扰,得到了满意的结果。     

电感耦合等离子体原子发射光谱法中Kalman滤波法解析重叠谱线的研究

考察了Kalman滤波技术校正ICP-AES中谱线重叠干扰的潜力.以新息序列的平均平方和为评价函数优化扫描光谱的峰位,消除扫描过程中可能产生的波长定位误差,从而保证滤波结果的准确性,并使实际检出限显著改善.在中等分辨率光谱仪和扫描步长为1.5pm的条件下,滤波器能有效地分辨峰间距只有4.8pm且峰形基本相同的重叠线对.对峰间距为9.8pm的重叠线对,当线背比低至0.05左右时仍能获得满意结果.连续背景用理论描述,因而样品溶液和纯组分溶液的光谱扫描无需扣除溶剂空白.     

电感耦合等离子体原子发射光谱分析研究进展

介绍了近年来国内在电感耦合等离子体原子发射光谱分析(ICP-AES)有关基础理论、仪器设备、进样技术和ICP-AES应用方面取得的研究进展。引用文献76篇。     

电感耦合等离子体原子发射光谱法测定食醋中砷

通过选择电感耦合等离子体原子发射光谱仪的最佳工作条件 ,对山西的出口食醋样品经稀释后直接测定 ,分析结果满意。回收率在 99.0 %～ 10 0 .2 %之间 ,相对标准偏差≤ 2 .6%。与国标规定的方法相比 ,此法简便快速 ,砷的检出限为 0 .0 33mg·kg-1。     

用自适应滤波校正电感耦合等离子体原子发射光谱分析中的光谱干扰

本文从分析谱线与干扰的统计特性出发，将信号处理技术的自适应嗓声抵消模型用于校正ＩＣＰ－ＡＥＳ中的光谱干扰。模拟与实测光谱校正结果表明，光谱干扰自适应滤波方法是可行的、有效的。     

电感耦合等离子体原子发射光谱分析中的光谱干扰及其校正的研究进展

对电感耦合等离子体原子发射光谱法分析中的光谱干扰来源(包括谱线重叠干扰和背景干扰)及其校正方法(仪器装置的改进、选择合适的分析线、背景校正法、干扰系数校正法、标准加入法、谱线拟合法、卡尔曼滤波法和导数光谱法等)的研究进展进行了综述(引用文献58篇)。     

电感耦合等离子体原子发射光谱法分析中有机溶剂效应

综述近年来电感耦合等离子体原子发射光谱法分析中有机溶剂效应,内容包括有机溶剂对等离子体物理特性的影响,有机溶剂对等离子体雾化进样系统的影响,有机溶剂对等离子体光谱特性的影响以及有机溶剂效应干扰消除,引用文献41篇.     

电感耦合等离子体原子发射光谱法测定柑橘中镧系元素含量

应用电感耦合等离子体发射光谱法同时测定柑橘中的5种稀土元素镧、铈、镨、钕和钐.对分析线选择、积分时问的选择、消解方法的选择、介质的影响等进行了试验.与干灰化法相比较,微波消解法处理样品所得结果的准确度和精密度更好.选择波长为333.749,418.660,390.844,415.608及359.260 nm 5条谱线依次作为测定镧、铈、镨、钕和钐的分析线,测得5种稀土元素的检出限(3s/k)依次为0.003 3,0.017 0,0.014 0,0.039 0及0.007 8 mg·L-1.应用此法测定了沙田柚中5种稀土元素的含量,回收率在96.8%～101.0%之间,相对标准偏差(n=5)小于5.5%.与GB/T 5009.94-2003法比较,经t检验,在置信水平α=0.05时,测定沙田柚时两种方法无显著性差异.     

荧光光度法中Kalman滤波法指示未知组分的研究

以苯丙氨酸、酪氨酸和色氨酸三组分体系的荧光光度分析为例, 研究了Kalman滤波法指示未知组分的潜力。根据新息序列的白噪音特性, 建立指示函数, 并确定指示函数的临界值, 指示未知组分存在; 并根据相对新息序列的形状可大致估计未知组分的荧光光谱的形状和峰位。     

Quality of calibration in inductively coupled plasma atomic emission spectrometry

Calibration is a crucial step during the whole analytical process. A procedure is suggested to assess the quality of linear regression used for the calibration graph, based on the use of confidence limits for the concentration, as the regression coefficient is not appropriate for this purpose. This procedure has been applied to inductively coupled plasma atomic emission spectrometry. It indicates that the use of only three standards should be discouraged because of unacceptably high confidence limits for the concentration. Moreover, use of weighted regression is more adequate in performing the least squares method and provides more constant confidence limits over the concentration range used to construct the calibration graph. This procedure could be easily added to any commercially available ICP system software.     

Carbon-related matrix effects in inductively coupled plasma atomic emission spectrometry

In Inductively Coupled Plasma Atomic Emission Spectrometry (ICP-AES), it has been observed that the emission intensity of some atomic lines is enhanced or depressed by the presence of carbon in the matrix. The goal of this work was to investigate the origin and magnitude of the carbon-related matrix effects in ICP-AES. To this end, the influence of the carbon concentration and source (i.e. glycerol, citric acid and potassium hydrogen phthalate), the experimental conditions and sample introduction system on the aerosol characteristics and transport, plasma excitation conditions and the emission intensity of several atomic and ionic lines of a total of 15 elements has been studied. Results indicate that carbon related matrix effects do not depend on the carbon source and they become more severe when the amount of carbon loaded into the plasma increases, i.e., when using: (i) carbon concentrations higher than 5 g L^− 1; (ii) high sample uptake rates; and (iii) efficient sample introduction systems. Thus, when introducing carbon into the plasma, the emission intensity of atomic lines with excitation energies below 6 eV is depressed (up to 15%) whereas the emission intensity of atomic lines of higher excitation energies (i.e. As and Se) are enhanced (up to 30%). The emission intensity of the ionic lines is not affected by the presence of carbon. The origin of the carbon-related interferences on the emission intensity of atomic lines is related to changes in the line excitation mechanism since the carbon containing solutions show the same aerosol characteristics and transport efficiencies as the corresponding aqueous solutions. Based on the previous findings, a calibration approach for the accurate determination of Se in a Se-enriched yeast certified material (SELM-1) has been proposed.     

Effect of sodium during the aerosol transport and filtering in inductively coupled plasma atomic emission spectrometry

Robust conditions, i.e. high R.F. power and low carrier gas flow rate were used to minimize the role of the plasma and to emphasize the contribution of the sample introduction system in the effect of Na in ICP-AES. Two combinations of pneumatic nebulizers and spray chambers were selected to obtain different Na effects. A conespray nebulizer was used with a cyclone spray chamber, and a cross-flow nebulizer was coupled to a double-pass spray chamber. A decrease in the ICP-AES analyte signal was observed with Na solutions under so-called robust conditions, irrespective of the sample introduction system employed. The cross-flow nebulizer associated with the double-pass spray chamber was more sensitive to Na presence than the other combination. These observations can be partially explained by a decrease in the solvent transport rate observed in presence of Na. It has been found that, in every case, the presence of Na did not modify the characteristics of the primary aerosol, while the tertiary aerosol is significantly modified. Finer droplets were obtained at the exit of the spray chamber when Na was present. Also, recirculation of the aerosol led to a significant element enrichment of the largest droplets for the Na solutions. It can be concluded that the effect of Na occured during the aerosol transport and filtering through the spray chamber.     

Interface for capillary electrophoresis coupled with inductively coupled plasma atomic emission spectrometry.

A modified concentric nebulizer was used as the interface to couple capillary electrophoresis (CE) to inductively coupled plasma atomic emission spectrometry (ICP-AES). The CE capillary replaces the central tube of the concentric nebulizer. The tip of the nebulizer tapers slowly to allow uncertainty in the position of the capillary. A platinum wire was inserted into the CE capillary to provide electrical connection to the CE power supply. pH changes inside the capillary due to electrolysis of the background buffer electrolyte was small and has minimal effects on the CE separation. The peak broadening effects due to the nebulizing gas flow, however, were significant. Resolution decreases quickly when the flow-rate of the carrier gas increases. Sample stacking technique was used to improve the resolution of species of opposite charge, e.g., Cr(VI) vs. Cr(III) ions. Detection limit of Cr based on peak area is approximately 10 ppb for the CE-ICP-AES system.     

Spectrum stripping in rapid sequential atomic emission spectrometry with the inductively coupled plasma

Rapid sequential atomic emission spectrometry with the ‘Zig Zag’ acquisition system (ISA Jobin Yvon, France) in the case of the inductively coupled plasma is described. The ‘Zig Zag’ system is shown to enable the application of spectral stripping, as both the reproducibility of the intensities measured, for several lines of Fe, and the reproducibilty of the wavelength positioning (errors below 3 pm in the 2nd order and 5 pm in the 1st order) were found to be high. Using an integration time of only 2.5 ms/point, the precision of the intensities expressed as the relative standard deviation is below 5%. These features are shown to allow spectrum stripping from the contribution of a Zr matrix, which has a rather line-rich atomic emission spectrum. Spectrum stripping was applied in the wavelength range from 237.9 to 241.1 nm, where 10 of the most sensitive emission lines of Fe were found. For sample solutions with 500 mg/l Zr only, 10 mg/l Fe only, 500 mg/l Zr as well as 10 mg/l Fe, and for a blank solution, respectively, five spectral scans were averaged and the averaged spectral scan for a blank solution was subtracted. The spectral scan obtained for a solution containing 500 mg/l Zr only was subtracted from the one obtained for the solution containing both 500 mg/l Zr and 10 mg/l Fe. The result of spectral stripping is comparable to the experimentally obtained spectral scan for the solution containing 10 mg/l Fe only after blank subtraction. The recovery for Fe was found to be 93±2% and is therefore comparable to the one obtained by chemical separation methods using solvent extraction. When using an integration time of 50 ms per measurement point instead of 0.5 ms/point, as it is possible in the case of the ‘Zig Zag’ approach, the detection limit for Fe in the measurement solutions can be improved from 20 down to 3 μg/l, or from 40 to 6 μg/g Zr, respectively.     

Correlation study of internal standardization in inductively coupled plasma atomic emission spectrometry

Correlation studies (calculation of the cross-correlation function and correlation coefficients) were carried out between fluctuations in the emission signals from various analyte and internal standard elements. Some statistics are presented which may help give a clearer picture of the utility of the internal standard principle. Improvements in precision brought about by the use of suitable standards are in the region of a factor of two. The use of argon emission lines as internal standards does not prove effective as an inverse correlation is observed between the emission of these lines and analyte lines.     

Enhancement effect of organic solvents in inductively coupled plasma atomic emission spectrometry

Summary The enhancement factors of various organic solvents in inductively coupled plasma atomic emission spectrometry (ICP-AES) were measured for diethyldithiocarbamate-cadmium(II) or mercury(II)-solvent systems by comparing the maximum emission intensity of an extract with that of the corresponding aqueous solution. The correlation between the enhancement factors obtained and physical parameters of the solvents were investigated. Among them, the best inverse linear relationship existed between log dielectric constant and log enhancement factor. The plot of log (boiling point x viscosity) vs. log enhancement factor also resulted in a line with a negative slope except water. Carbon tetrachloride, chlorofom and xylene, which gave much larger enhancement factors, were recommended for the use in ICP-AES.

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Verstärkungseffekt durch organische Lösungsmittel in der ICP-AES

     

Determination of phosphorus in fertilizers by inductively coupled plasma atomic emission spectrometry

An inductively coupled plasma atomic emission spectrometry (ICP-AES) method was developed for the determination of phosphorus in fertilizers. Total phosphorus, direct extraction available phosphorus (EDTA), and water-soluble phosphorus, reported as phosphorus pentoxide (P205), in 15 Magruder check fertilizers were measured by ICP-AES, and the results were compared with those obtained by the AOAC official method. Five analytical wavelengths of phosphorus, 177.499, 178.287, 213.618, 214.914, and 253.565 nm, were tested for the determination of phosphorus in fertilizers, and their detection limits were obtained. Acid effects of perchloric acid and possible matrix effects of aluminum, calcium, magnesium, potassium, and sodium were negligible for phosphorus determination. Wavelength 213.618 nm was the best analytical wavelength for phosphorus determination by all 3 sample preparation methods for the selected Magruder fertilizers. The results demonstrated that the accuracy and precision of the ICP-AES method were comparable with those of the official methods.