共查询到20条相似文献,搜索用时 43 毫秒
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Parijat Roy Vysetti Balaram Anil Kumar Manavalan Satyanarayanan Thota Gnaneshwar Rao 《Geostandards and Geoanalytical Research》2007,31(3):261-273
Data on thirty-four minor and trace elements including all rare earth elements (REE) are reported for two kimberlitic international reference materials (SARM-39, MINTEK, RSA and MY-4, IGEM, Russia) by inductively coupled plasma-mass spectrometry (ICP-MS), some of them for the first time. Four digestion techniques (open acid, closed vessel acid, microwave and lithium metaborate fusion digestion) were used for the decomposition of samples for analysis by ICP-MS. Three other reference materials (USGS BHVO-1, CRPG BR-1 and ANRT UB-N) were analysed simultaneously using the same analytical methodology to assess the precision and accuracy of the determinations. The data obtained in this study compare well with working values wherever such values are available for comparison. Though open acid digestion was found to be very rapid, effective and convenient for the determination of several trace elements in kimberlitic samples, recoveries for heavy rare earth elements (HREE) were lower than the respective recoveries obtained by the other decomposition techniques used. The precision obtained was better than ± 6% RSD in the majority of cases with comparable accuracy. Chondrite-normalised plots of each RM for all the digestion techniques were smooth. The new data reported on the two kimberlitic reference materials make these samples useful for future geochemical studies of kimberlitic rocks. 相似文献
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《Applied Geochemistry》2006,21(5):756-765
The continuous flow elemental analyzer-isotopic ratio mass spectrometer (EA-IRMS) technique provides a significant improvement over conventional extraction methods for the determination of C- and S-isotope ratios in geological materials. It is faster and requires much smaller quantities of material for analysis. Sample preparation is simple, with little or no need for chemical or complete mechanical mineral phase separation, and EA-IRMS sample introduction is rapid. However, because of its simplicity and the fact that data quality depends on the control of a variety of factors, the technique requires rigid adherence to a careful sample analysis protocol.The matching of sample and reference peak heights by sample weight adjustment minimizes non-linearity effects. An accurate calibration should be determined by using standards having a wide range of isotopic compositions, ideally bracketing the samples analysed to both low and high isotopic ratios, and a regular analysis of standards undertaken to maintain the accuracy of the calibration. The calibration equation must be monitored throughout the run by regular analysis of standards, and performance of the Cu-reduction reactor regularly checked to avoid O2 saturation. With this level of attention to analytical detail, measured precision on replicates of isotopic standards is in the order of ±0.1‰ for both C and S isotopic analyses. For S this is a significant improvement over conventional techniques, with 53% of natural samples analysed replicating to better than ±0.1‰. 相似文献
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较低稀释比熔片制样X射线荧光光谱法测定磷矿石中12种主次痕量组分 总被引:4,自引:4,他引:0
当前应用X射线荧光光谱熔片制样技术分析测定较低含量、低荧光产额氟组分时,准确度较低,精密度较差、检出限较高。本文运用5:1较低稀释比熔样制片技术,采用波长色散X射线荧光光谱法测定磷矿石中12个主次量组分(F、Na2O、MgO、Al2O3、SiO2、P2O5、K2O、CaO、TiO2、MnO、TFe2O3和痕量SrO)。采用磷矿石、岩石国家一级标准物质、磷矿石管理样品和人工配制标准样品校准,经验系数法进行基体校正,结果表明12个组分分析方法的精密度和准确度较好,检出限较低,未知样品的分析结果比较满意;氟的精密度、准确度和检出限均好于文献中10:1熔样稀释比得出的结果。该方法解决了压片制样测定氟组分,熔片制样测定其他主次量组分的技术问题,同时也降低了熔片制样技术测定氟的检出限。 相似文献
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A critical evaluation of trace element data derived by energy dispersive X-ray fluorescence (ED-XRF) analysis of over 40 geochemic reference samples shows that results for Rb, Sr, Y, Zr, Nb, and Th can be at least as good in terms of precision (better than ± 2 ppm (2s) or ± 3 % (2s relative), accuracy, and 3s detection limits (2 to 4 ppm) as those obtainable by other routine multi-element analytical techniques. Data obtained simultaneously for Ni, Cu, Zn, Ga, Pb and U are less precise because excitation conditions are less well optimised (with 3s detection limits of 6 to 12 ppm). The quality of data and the efficiency of simultaneous analysis of both sets of elements is well-suited to most geological applications. Following a critical appraisal of calibration accuracy, new trace element data are presented for 15 reference samples from the Geological Survey of Japan. 相似文献
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随着超净化实验室条件的完善以及多接收同位素质谱技术的成熟,铅同位素双稀释法倍受关注。用双稀释法测定铅同位素比值的方法原理,以及^204Pb—^207Pb双稀释剂的配制和标定方法。通过对标准物质NBS981和地质样品的分析测定,表明用双稀释法测定铅同位素比值,可以有效校正由质谱分析造成的同位素分馏效应,从而提高分析结果的精度和准确度。 相似文献
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基于最优加权组合模型及高斯-牛顿法的滑坡变形预测研究 总被引:1,自引:0,他引:1
在对最优加权组合理论和高斯-牛顿法优化非线性模型参数的方法研究的基础上,依托于洒勒山滑坡的实际变形监测资料,建立了该滑坡变形预测的3个非线性预测模型:指数模型、Verhulst模型和灰色GM(1,1)模型;利用最优加权组合理论建立了洒勒山滑坡的最优加权组合预测模型,并运用高斯-牛顿法对各单一模型和组合模型的参数进行了优化。通过对比分析得出:组合模型的预测精度高于任何单一模型的预测精度;参数优化后各单一模型的预测精度都有不同程度的提高;参数优化后的组合模型预测精度是最高的。因此,综合运用最优组合理论和高斯-牛顿法处理滑坡预测预报模型,是提高滑坡预测预报精度的行之有效的方法。 相似文献
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通过高温管式燃烧炉分解试样,采用二乙烯三胺-乙醇胺-茜素黄-百里香酚酞非水滴定体系,完成多目标区域地球化学勘查样品全碳量的测定,方法检出限、精密度、准确度均能达到多目标区域地球化学勘查样品测试规范要求。试样中的硫用碘酸钾-淀粉吸收液吸收,消除其对全碳测定的影响。 相似文献
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全谱直读ICP发射光谱测定低冰镍中砷 总被引:1,自引:1,他引:0
对低冰镍样品中的砷进行了试验,采用硝酸分解试样,在ICP发射光谱上测定砷元素。本法采用冶标准样品进行实验,结果与标准值基本相符,其精确度与准确度均能满足低冰镍分析的要求。 相似文献
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如何准确地判识和评价滑坡的稳定性一直是滑坡研究中的关键问题。基于多分类支持向量机的基本理论,利用三峡库区的37个典型滑坡(27个训练样本,10个测试样本),建立了滑坡稳定性判识的多分类支持向量机模型,并与距离判别分析方法进行了比较。结果表明,SVM模型对测试样本和训练样本的判识准确率均达到100%,而距离判别法对测试样本和训练样本的判识准确率分别为80%和77.8%,前者的判识精度明显优于后者。在此基础上,将SVM模型运用于溪洛渡库区牛滚凼滑坡的稳定性判识中,结果与实际情况吻合较好。 相似文献
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A.L. Meier 《Journal of Geochemical Exploration》1980,13(1):77-85
Gold in geologic material is dissolved using a solution of hydrobromic acid and bromine, extracted with methyl isobutyl ketone, and determined using an atomic-absorption spectrophotometer equipped with a graphite furnace atomizer. A comparison of results obtained by this flameless atomic-absorption method on U.S. Geological Survey reference rocks and geochemical samples with reported values and with results obtained by flame atomic-absorption shows that reasonable accuracy is achieved with improved precision. The sensitivity, accuracy, and precision of the method allows acquisition of data on the distribution of gold at or below its crustal abundance. 相似文献
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悬浮月尘存在污染月表就位光谱仪反射定标板的可能。文中工作模拟并分析了近红外光谱仪反射定标板在无污染、受轻度和重度污染情况下对模拟月壤矿物混合物光谱指纹特征及定量分析模型预测精确度的影响。结果表明:以受污定标板为参比的月壤矿物混合物反射光谱在反射率和指纹特征上均异于无污染样品,且污染越重差异越大;用无污染光谱数据建立的偏最小二乘(PLS)定量分析模型,预测受污样品时其预测精确度显著降低;采用受污后光谱数据重建PLS模型会在一定程度上能提高受污样品的预测准确度。该研究和获得的结论,在星表光学载荷的设计、数据校正以及定量分析模型预测能力评估等方面具有一定的指导意义。 相似文献
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在水力因素多变的长江下游感潮河段建立ADCP在线测流系统实时采集指标流速,可选用合适的方法推求断面平均流速,从而实现流量的实时报汛和整编。多元线性回归分析和BP神经网络具有原理明晰、实现便捷等特点,为比较以上两种方法在断面平均流速计算中的优劣,以南京水文实验站2014年以来实测数据为例,分析不同情况下两种模型的拟合精度和预测精度。结果表明,两种模型均具有较好的有效性、精确性和稳定性,且拟合精度与模型选用的监测指标有关;对于只采用单一指标流速而言,BP神经网络模型的结果明显优于多元线性回归模型。同时,两种模型都能较好的预测断面平均流速,其中BP神经网络适应更好。 相似文献
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讨论了同位素地质样品分析的质量监控与质量评估问题,提出在同位素地质样品分析中以准确度与精度度并重、标准物质监控与重复样监控相结合的质量监控方法。通过对大量标准样品定值数据与积累的测试数据的统计分析,提出了标准物质测定误差和标准偏差及重复样双份分析的双差允许限的确定方法,并采用准确度分数、精密度分数、空白分数和系统性偏倚分数对测试结果的质量进行定量评估的方法,这些方法适用于实验室内部的质量监控和评估 相似文献
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