共查询到19条相似文献,搜索用时 125 毫秒
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样品中痕量元素的分析及其容器的选择和清洗 总被引:1,自引:0,他引:1
绪言对痕量元素的测定,特别是液体样品,由于空白分析产生的偏差,通常认为大部分是由于采样和贮藏容器的污染而引起的。对于液体样品中痕量元素的测定的改进取决于所用的塑料以及使用前所用的清洗方法。关 相似文献
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在痕量分析中,为获得准确的分析结果,容量材质以及洗涤方法的选择至关重要。试验分析表明:聚乙烯是较好的容器材料,它玷污最小、易洗涤、价廉、容器清洗。经实验证明:蒸汽法效果好,但需要相应装置;浸泡法简单易行,但消耗较大。其他方法则各有利弊,因此可根据不同的分析元素及特征,选择合适的洗涤方法。 相似文献
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甲醛吸收-副玫瑰苯胺分光光度法是测定环境空气中的二氧化硫的常用方法,该方法具有灵敏度高、选择性好等优点,但在实验分析过程中发现,该方法对实验室环境条件、反应条件、试剂的质量和实际操作要求严格。文章通过对影响空白值及检测结果的显色温度、显色时间、实验试剂、样品的采集及保存等关键因素进行实验分析,使校准曲线斜率和试剂空白吸光度值在给定的检测条件下满足检测方法标准的要求,为提高甲醛法测定空气中二氧化硫测量结果的准确性提供参考。 相似文献
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为改进环境标准HJ 680-2013检测方法,采用原子荧光光谱法测定混合酸水浴消解法前处理土壤和沉积物样品中痕量汞、砷、硒、铋和锑元素。以GBW07430、GBW07446、GBW07452探讨15种混合酸消解体系对不同类型样品痕量元素测定结果的影响,筛选得到采用盐酸-硝酸-硫酸-高氯酸-过氧化氢(体积比为4∶2∶0.5∶0.5∶0.5)体系为消解液的痕量检测最佳实验条件。水浴法消解前处理,消解时间为1.0h,处理时间为2.5h。5种元素的质量浓度范围在0.10~10.0 mg/kg线性相关系数大于0.999,检出限范围0.002~0.025 mg/kg,定量限范围0.008~0.100 mg/kg,测定结果的相对标准偏差范围为1.45%~5.19%,样品加标回收率范围为89.2%~119%。经国家一级土壤成分分析标准物质验证该方法,并成功应用于环境中农业与建筑用土壤及管道淤泥沉积物实际样品的前处理,结果准确可靠,适用多元素一次处理,解决高通量样品的测定需求,满足环境检测分析工作。 相似文献
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有机磷类农药残留分析检测技术研究进展 总被引:3,自引:0,他引:3
用样品前处理、样品分析检测两个方法,阐述近几年常用的有机磷类农药残留分析检测技术原理及优缺点,并提出未来样品前处理技术及有机磷类农药检测技术的发展趋势。 相似文献
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李湘宜 《中国环境管理干部学院学报》2012,(5):54-56,81
综述了化学发光法用于分析检测的基本原理,化学反应过程中产生光的量与发光物质的含量成正比。化学发光方法对环境样品检测具有灵敏度高、线性响应范围宽、可以实现自动化等优点,通过发射光的比率可以推定未知成分的浓度,测定环境样品中被测物质的量。化学发光法已广泛应用到环境样品检测、药物分析等领域。 相似文献
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E. Thomas Gilmore Preston D. Frazier Isaac J. Collins II William Reid M. F. Chouikha 《The Environmentalist》2013,33(4):477-485
Within the electronics industry, counterfeit electronic components entering the supply chain have steadily become an increasing threat accounting for more than 8 % of global merchandise trade and an annual $600 billion enterprise. Currently, there are not many cost-effective and nonintrusive solutions for counterfeit detection of electronic parts. In this paper, the authors present a statistical approach for detecting counterfeit components based on infrared (IR) analysis by the use of independent component analysis (ICA). As a prominent higher-order statistical analysis technique, ICA is capable of extracting relevant features from IR data. The latest applications and the extended algorithms of ICA have been elucidated for the purposes of classification and identification of counterfeit electronic parts. The theoretical framework of ICA is presented along with extensive experimental results to illustrate its feature extraction function in counterfeit electronic parts detection. 相似文献
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Edward B. Barbier 《Natural resources forum》1989,13(1):20-32
The global warming caused by emissions of CO2 and trace gases is expected to cause shifts in climatic zones and rainfall patterns, and possibly thermal expansion of oceans. There are likely to be impacts on global agriculture and the food security of low-income countries, as well as disruptions to major ecosystem complexes such as forests. Rising sea levels will threaten low-lying regions, coastal zones and islands. Policy-makers will therefore have to consider the relative costs and benefits of 'doing nothing', preventive measures and adaptive responses. Economics should play a key and innovative role in this analysis. 相似文献
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P. Steven Porter Robert C. Ward 《Journal of the American Water Resources Association》1991,27(4):687-700
ABSTRACT: The statistical analysis of data which have trace level measurements has traditionally been a two-step process in which data are first censored using criteria based on measurement precision, and then analyzed with statistical methods for censored data. The process might be more informative if data were left uncensored. In this paper, information loss attributable to censoring and measurement noise are assessed by comparing the sample mean and median of uncensored measurements with a log regression mean and median based on censored data. Measurements are derived from lognormal parent distributions which have random variability characteristic of trace level measurement. The relative performance of estimators used with error-free samples and with samples having measurement noise can be explained by differences between the probability distributions of parents and measurements. Measurement introduces bias and dispersion and transforms lognormal parent distributions toward greater symmetry. Estimates using uncensored data are less biased and more accurate than the log regression mean and median when censoring exceeds about 50 percent, and are not much worse at any fraction censored. For data with many (80 percent) results below the limit of detection, bias may be quite severe. 相似文献
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Application of enzyme-linked immunosorbent assay analysis for determination of monensin in environmental samples 总被引:1,自引:0,他引:1
There is growing concern that antibiotic use in livestock production is contributing to contamination of soil and aquatic environments. Monensin, a polyether ionophore antibiotic, accounts for approximately 13% of total subtherapeutic livestock antibiotic usage in the USA and has been widely detected in aquatic environments. Due to insufficient ultraviolet absorbance, liquid chromatography analysis of monensin in environmental samples is limited to equipment with mass spectrometry (e.g., liquid chomatography-mass spectrometry [LC-MS]). However, LC-MS equipment is costly, and extensive sample preparation and clean-up is often required. Rapid, low-cost analytical techniques are needed to monitor for monensin residues in the environment. In this study, a commercially available enzyme-linked immunosorbent assay (ELISA) for detecting monensin in animal feed extracts was evaluated for determination of monensin in water, soil, and manure. The monensin ELISA was highly sensitive, with limits of detection and quantification at 1.5 and 3.0 microg L(-1), respectively. Recovery of monensin in spiked water samples was approximately 100%. Cross-reactivity was not observed with similar polyether ionophores, tetracyclines, macrolides, or sulfonamides. Concentrations of monensin using ELISA were greater than concentrations measured with LC-MS. This is attributed to cross-reactivity of the monensin ELISA toward structurally similar monensin compounds, such as factors (slight naturally produced structural variants) and metabolites. Results from this study showed that ELISA can be a reliable, rapid, and low-cost alternative to LC-MS analysis of environmental samples. 相似文献
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Gräfe M Landers M Tappero R Austin P Gan B Grabsch A Klauber C 《Journal of environmental quality》2011,40(3):767-783
We describe the application of quantitative evaluation of mineralogy by scanning electron microscopy in combination with techniques commonly available at hard X-ray microprobes to define the mineralogical environment of a bauxite residue core segment with the more specific aim of determining the speciation of trace metals (e.g., Ti, V, Cr, and Mn) within the mineral matrix. Successful trace metal speciation in heterogeneous matrices, such as those encountered in soils or mineral residues, relies on a combination of techniques including spectroscopy, microscopy, diffraction, and wet chemical and physical experiments. Of substantial interest is the ability to define the mineralogy of a sample to infer redox behavior, pH buffering, and mineral-water interfaces that are likely to interact with trace metals through adsorption, coprecipitation, dissolution, or electron transfer reactions. Quantitative evaluation of mineralogy by scanning electron microscopy coupled with micro-focused X-ray diffraction, micro-X-ray fluorescence, and micro-X-ray absorption near edge structure (mXANES) spectroscopy provided detailed insights into the composition of mineral assemblages and their effect on trace metal speciation during this investigation. In the sample investigated, titanium occurs as poorly ordered ilmenite, as rutile, and is substituted in iron oxides. Manganese's spatial correlation to Ti is closely linked to ilmenite, where it appears to substitute for Fe and Ti in the ilmenite structure based on its mXANES signature. Vanadium is associated with ilmenite and goethite but always assumes the +4 oxidation state, whereas chromium is predominantly in the +3 oxidation state and solely associated with iron oxides (goethite and hematite) and appears to substitute for Fe in the goethite structure. 相似文献