Method for increasing the accuracy of the determination of elemental impurities in metals by spark source mass spectrometry

This paper presents a method for increasing the accuracy in the determination of impurities in metals by spark source mass spectrometry (SSMS). The method is based on the application of a parametric equation to calculate sensitivity coefficients. The parameters of this equation are determined from results obtained by analysis of an appropriate standard material. Concentrations in the sample of elements certified in the standard material are determined using experimental values of sensitivity coefficients, while the concentrations of remaining elements in the test sample are determined using coefficients calculated from the proposed parametric equation.     

An electrochemical enrichment procedure for the determination of heavy metals by total-reflection X-ray fluorescence spectroscopy

An electrolytic separation and enrichment technique was developed for the determination of trace elements by total-reflection X-ray fluorescence spectroscopy (TXRF). The elements of interest are electrodeposited out of the sample solution onto a solid, polished disc of pure niobium which is used as sample carrier for the TXRF measurement. The electrochemical deposition leads to a high enrichment of the analytes and at the same time to a removal of the matrix. This results in substantially improved detection limits in the lower picogram per gram region. The deposited elements are directly measured by TXRF without any further sample preparation step. The homogeneous thin layer of the analytes is an ideal sample form for TXRF, because scattered radiation from the sample itself is minimized. The proposed sample preparation method is useful particularly for the analysis of heavy metals in liquid samples with for TXRF disturbing matrices, e.g. sea water.     

X-ray fluorescence analysis of obsidian objects from Catamarca,Argentina

The concentrations of five trace elements (Rb, Zr, Sr, Ti and Mn) and one major (Fe) element have been determined in groups of obsidian samples by wavelength dispersive X-ray fluorescence spectrometry. Two methods were used for different elements on the basis of different excitation conditions and sample preparation procedures. Synthetic standards with compositions similar to those of the igneous stone were prepared into which the analytes were incorporated in solution. The method was used to establish the provenance of a number of prehistoric obsidian artifacts. The results ascertained in these analyses are discussed in this paper.     

Simultaneous determination of germanium,arsenic, tin and antimony with total-reflection X-ray fluorescence spectrometry using the hydride generation technique for matrix separation—first steps in the development of a new application

This paper introduces a new perspective for total-reflection X-ray fluorescence analysis (TXRF), that is the simultaneous determination of Ge, As, Sn and Sb in seawater. As is well known from atomic absorption spectroscopy (AAS) and inductively coupled plasma techniques (ICP) compounds of these elements can be reduced by sodium borohydride to their hydrides and thus separated from the matrix. In this work the hydride generation is used for matrix separation in TXRF measurements. For this purpose the following procedures are considered: (1) Preconcentration of hydrides by absorption in solvents, and evaporation of some μl of this solution on the sample carrier. (2) Decomposition of hydrides in a heated thin silica tube, or at rough and/or catalytically active surfaces, e.g. in adequately prepared columns, eluting of the species by acid and evaporation of some μl of this solution on the sample carrier. (3) Decomposition of hydrides directly on the surface of a heated silica sample carrier as a thin amorphous film. (4) Combustion of hydrides in the hydrogen flame and deposition of an elemental film on the sample carrier. Basically, all four ways have been tested and the results are promising. © 1997 Elsevier Science B.V.     

Application of an on-line preconcentration system in simultaneous ICP-AES

A PC-controlled on-line preconcentration system (TRACECON) developed by Knapp et al. [11], was connected to a JY-70 Plus simultaneous ICP spectrometer to preconcentrate on-line seven trace elements (Cu, Fe, Zn, Cr, Ni, Mn, V) in biological and environmental samples. EDTrA-cellulose was used as column material. The elemental concentrations were determined by simultaneous ICP-AES. The effect of pH of the sample solution on the enrichment was studied. It was found that the recoveries of chromium and iron depend strongly on the pH of the sample solution. All the elements mentioned were recovered quantitatively at pH 4.0±0.1. The flow rates of sample solution and element solution were optimized. The enrichment factors for seven elements at 5 ml loading volume range from 3.9 for Cu to 7.9 for Zn. The detection limits of all seven elements were improved. The accuracy of the method was tested by the analysis of a number of CRMs of NIST, BCR and NIES. Most results are in good agreement with the certified values.On leave from Shanghai Institute of Metallurgy, Academia Sinica, Shanghai 200050, People's Republic of China     

Preconcentration of trace elements by partial dissolution of the matrix—multielement preconcentration from manganese

Trace elements such as Ag, Au, Bi, Cd, Co, Cu, Fe, Ga, In, Ni, Pb, Pd and Tl, can be preconcentrated with recoveries of better than 95% from high-purity manganese if the sample is coated with a thin layer of mercury before its dissolution in HCl to a small residue. For determination of the trace elements, the residue is completely dissolved in aqua regia. After separation of the mercury by reductive precipitation, Bi, Cd, Co, Cu, Fe, Ga, In, Ni, Pb, and Tl are determined by flame a.a.s. ('injection method'). Ag, Au and Pd are determined in the mercury-containing solution. The relative standard deviation was usually about 5%; Cu, Fe and Pb were proved to be inhomogeneously distributed in the sample (electrolytically produced manganese), and so the standard deviations were considerably greater. The detection limits for the different elements were between 0.6 and 0.004 ppm, depending on the sensitivity of their a.a.s. determination. The theoretical basis of this preconcentration method and its applicability to multielement analysis of different high-purity metals are discussed.     

在火焰原子吸收光度计上以无火焰原子化法测定碱金属元素

在常规火焰原子吸收分光光度计上采用特制的不锈钢原子化管对碱金属元素进行无火焰原子化法测定,克服了碱金属元素在火焰中的电离效应,试液用量极少。测定结果的相对标准偏差小于0.3%(n=11),回收率为98.9%~99.2%。     

Analysis of liquid samples using dried-droplet laser ablation inductively coupled plasma mass spectrometry

In this study we developed a dried-droplet method for laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS). The proposed method provides accurate and precise results when building calibration curves and determining elements of interest in real liquid samples. After placing just 1 μL of a liquid standard solution or a real sample onto the filter surface and then converting the solution into a very small, thin dry spot, the sample could be applied as an analytical subject for LA. To demonstrate the feasibility of this proposed method, we used LA-ICP-MS and conventional ICP-MS to determine the levels of 13 elements (Li, V, Mn, Co, Ni, Cu, Zn, As, Mo, Cd, Sb, Tl, and Pb) in five water samples. The correlation coefficients obtained from the various calibration curves ranged from 0.9920 (²⁰⁵Tl) to 0.9998 (⁵¹V), sufficient to allow the determination of a wide range of elements in the samples. We also investigated the effects of Methylene Blue (MB) and the NaCl concentration on the elemental analyses. MB could be used as an indicator during the ablation process; its presence in the samples only negligibly influenced the intensities of the signals of most of the tested elements. Notably, high NaCl contents led to signal suppression for some of the elements. In comparison with the established sample introduction by nebulization, our developed technique abrogates the need for time-consuming sample preparation and reduces the possibility of sample contamination.     

便携式钨丝电热原子吸收光谱仪测定天麻中的铅

采用微波消解-小型钨丝电热原子吸收光谱仪在优化条件下测定了天麻中的铅。进样10μL时,检出限为10.1μg/L。对600μg/L铅标准溶液进行5次连续测定,测定结果的相对标准偏差为5.2%。铅的线性范围为100~1500μg/L,回归方程为A=0.0002c-0.0103,线性相关系数r=0.995 8。该法测定结果与电感耦合等离子体发射光谱仪(ICP-OES)测定结果接近,该方法简便、快速,可用于天麻样品中痕量铅的测定。