干法灰化和湿法消解植物样品的铜锌铁同位素测定对比研究

测定有机样品中元素含量和同位素时,处理样品常用的方法有干灰化法和湿法两种.目前,测定样品中Cu、Zn、Fe同位素时,多采用湿法处理样品.相对于湿法处理样品,干灰化法溶样迅速、耗酸量少,适合处理大量样品,但高温灼烧过程可能会导致样品中Cu、Zn、Fe同位素的分馏.本研究利用海州香薷植株,以湿法为基础,对干灰化法和湿法处理...     

http://www.sciencedirect.com/science/article/pii/S1674987111000193

Geochemical subsoil data obtained from China and European laboratories have been compared in this study. 787 C horizon subsoil samples from FOREGS (Forum of European Geological Surveys) geochemical baselines mapping project were sent to China’s IGGE (Institute of Geophysical and Geochemical Exploration) laboratory and composited to 190 samples according to the 160 km 160 km GNT (Global Terrestrial Network) cells. In addition to the FOREGS elemental analysis package, Au, Pt, Pd, B, Ge, Br, Cl, Se, N, Li and F were also analyzed by using the IGGE’s 76 element analytical scheme. Geochemical data statistics, scatter plotting, and geochemical map compilation techniques have been employed to investigate differences between FOREGS and IGGE analytical results. The results of two datasets, the IGGE’s analysis data for composited samples, and the FOREGS average data of samples in each GNT cell, agree extremely well for about 23 elements, viz: SiO2, Sr, Al2O3, Zr, Ba, Fe2O3, Ti, Rb, Mn, Gd, CaO, Ga, MgO, P, Pb, Na2O, Y, Th, As, U Sc, Cr, and Co. There are slight differences between-laboratory biases shown as proportional errors between the datasets for Ni, K2O, Tb, Tl, Cu, S, Sm, La, Ce, Pr, Nd, Eu, Ho, Er, Tm, Yb, Lu, Ta, Nb, Hf, and Dy. For Cd, Cs, Be, Sb, In, Mo, I, Sn, and Te, the correlation of the two datasets and the similarity of the geochemical maps are fairly good, but obvious biases exist between the two datasets at values near detection limits. Sensitivities of FOREGS analytical methods for W, Bi, Sn, Te, Be, and I are insufficient to produce reportable values in at least 80% of the samples. Although the detection limits of Ag for both FOREGS and IGGE are sufficient to provide reportable values, a large bias was found between the two datasets. This study demonstrates that consistent analytical data for certain elements of global geochemical mapping samples can be achieved by different qualified laboratories, such as China’s IGGE laboratory and some European laboratories. For some elements, such as Ag, further research on the selection of the proper analytical methods and on the development of quality control methods should be undertakendwith final recommendations adhered to by all participants of the global geochemical mapping program.     

锍镍试金技术制备含铂族元素硫化物微区分析标准样品的可行性

激光剥蚀电感耦合等离子体质谱(LA-ICP-MS)适合于直接分析硫化物矿物中痕量元素的含量及空间分布,但硫化物矿物的激光剥蚀特性与硅酸盐及氧化物不同,受到的干扰也更严重,且由于硫化物标准物质(尤其是含铂族元素、Au、Ag等贵金属元素标准物质)极度缺乏,限制了LA-ICP-MS技术在硫化物微区分析中的广泛应用。本文以贵金属标准样品GPT-9和矿石标准物质为原料合成锍镍试金扣,并封入真空管中重熔,利用背散射电子图像和LA-ICP-MS分析元素分布的均匀性,探讨真空重熔锍镍试金扣制备硫化物原位微区分析标准样品的可行性。背散射电子图像(BSE)显示真空重熔后锍镍试金扣由单相S、Ni化合物组成。LA-ICP-MS线扫描和点扫描分析表明,锍镍试金扣中S、Ni、Cr、Co、Cu、Pb、Sb、Cd、Bi等主量及微量元素分析精密度(RSD)均小于10%,均匀分布;在镍扣制备过程中Zn相对于Cu、Pb、Sb更难进入硫化物相;贵金属元素Au、Ag、Pt均一性较好,其余贵金属元素由于含量低、仪器波动及质谱干扰等影响因素造成分析数据的RSD相对较大,但可通过提高原料中贵金属元素含量、降低熔融样品淬火温度等方法进一步提高其均匀性。锍镍试金扣的组成元素对铂族元素分析的质谱干扰研究表明,重铂族元素(Os、Ir、Pt)和Au受到的干扰可忽略不计;轻铂族元素(Ru、Rh、Pd)受金属氩化物干扰较为严重,需进行干扰校正。研究认为,真空重熔技术可有效提高锍镍试金扣中各元素(包括贵金属)的均一性,达到硫化物原位微区分析标准样品的要求,利用真空重熔锍镍试金扣制备LA-ICP-MS原位微区痕量及贵金属硫化物分析标准样品具可行性。     

矿化地球化学样品的测试质量风险及对策

由于矿化样品的某种元素的含量高,对其他元素的测量产生了干扰,在质量参数均不超差的情况下,漏报、误报的风险极大。本文针对内蒙古自治区呼伦贝尔市八间房1：5万区域地质勘查调查样品中的10件矿化样品的铅的测试进行了方法比对试验,由于样品中钙量高,对原子吸收光谱法测铅产生了干扰,测试结果远远高于真实值。因此建议实验室在进行地球化学样品分析时,内检分析和异常抽查分析应尽量采用与基本分析不同的分析方法,规避误报、漏报的风险。     

Effect of sampling plan and trend removal on residual uncertainty

ABSTRACT

The ground is one of the most highly variable of all engineering materials. As a result, geotechnical designs depend upon a site investigation to estimate the ability of the ground to perform acceptably. For example, when a shallow foundation is being proportioned to avoid a bearing capacity failure under a certain applied load, the frictional and cohesive properties of the ground under the foundation must first be estimated through a site investigation. Questions which arise are: How does the quality and intensity of the site investigation affect the design? Is more investigation cost effective? If the site is sampled at one location and the foundation placed at a different location, how does this mismatch affect the target design and the reliability of the final foundation? By modelling the ground as a spatially variable material, questions such as the above can be investigated through Monte Carlo simulation and sometimes theoretical probabilistic models. Using such tools, this paper looks specifically at how the intensity (frequency and spatial distribution) of a site sampling plan, and how the samples are used, affects the understanding of the ground properties under a foundation. Interestingly, it is found that removing the sample mean outperforms removing the best linear unbiased estimate (BLUE) when the actual field correlation length is small but the BLUE correlation length is assumed equal to the field size. Recommendations are made regarding number of samples and the type of trend to best characterise the field.

Abbreviations: BLUE: best linear unbiased estimate; MCS: Monte Carlo simulation; LAS: local average subdivision     

电感耦合等离子体质谱法测定地质样品中铜锌铕钆铽的干扰及校正

由于电感耦合等离子体质谱(ICP-MS)分析不是在封闭的真空系统中进行,在测定过程中,气体、水和酸产生的一些离子都可能进入检测系统,产生干扰,严重影响痕量元素的准确分析。文章采用氢氟酸-硝酸封闭压力酸溶分解样品,ICP-MS法同时测定地质样品中Cu、Zn、Eu、Gd、Tb,研究了Ti、Ba、Ce、Pr、Nd对Cu、Zn、Eu、Gd、Tb的干扰情况。实验选择质量数65Cu、66Zn、153Eu、157Gd、159Tb作为测定同位素,用干扰系数脱机校正法校正分别来自Ti、Ba、Ce、Pr、Nd的氧化物重叠干扰,有效地解决了被干扰元素在测定时数值准确度低的问题。方法检出限(稀释因子1000)为:Cu 0.47μg/g、Zn 0.82μg/g、Eu 0.002μg/g、Gd 0.004μg/g、Tb 0.002μg/g,方法精密度(RSD,n=12)<5%,准确度(RE)<5%。方法用岩石、土壤、水系沉积物国家一级标准物质进行验证,测定值与标准值相符,适用于地质样品中Cu、Zn、Eu、Gd、Tb的测定。     

高分辨电感耦合等离子体质谱法测定地球化学样品中的 36种元素

土壤和水系沉积物地球化学样品经氢氟酸-硝酸-高氯酸敞开酸溶消解,王水提取,试液直接用高分辨率电感耦合等离子体质谱法(HR-ICP-MS)同时测定其中的Li、Be、P、Sc、Ti、V、Cr、Mn、Co、Ni、Cu、Zn、Ga、Rb、Sr、Nb、Mo、Cd、In、Sb、Cs、Ba、Hf、Ta、W、Tl、Pb、Bi、Th、U、Na2O、MgO、Al2O3、K2O、CaO、TFe2O3等36种组分。对各元素的测定同位素及分辨率进行优选,有效消除了绝大多数多原子及双电荷离子干扰的影响。痕量元素的方法检出限(6σ)在0.002～2.031μg/g之间,主量元素的检出限(6σ)在10.0～100μg/g之间(稀释因子=1000),所有元素的相对标准偏差(RSD,n=12)均小于10%。方法经国家一级地球化学标准物质验证,测定值与标准值吻合。     

二苯硫脲泡塑富集-原子吸收光谱法连续测定化探样品中金和银

传统的发射光谱、化学光谱、泡塑富集分离-原子吸收光谱法测定化探样品中的金和银,分析结果不稳定,效率低。本研究提出用50%的王水分解化探样品,负载二苯硫脲泡塑吸附金银,石墨炉和火焰原子吸收光谱法对金和银进行联合测定。在二苯硫脲浓度、吸附酸度、吸附温度、振荡时间等优化的实验条件下,金和银的回收率分别达到97.9%和98.8%,检出限为0.25 ng/g和0.038μg/g,准确度(RE,n=9)为2.0%～14.0%和7.7%～13.3%,精密度(RSD,n=9)为3.1%～12.4%和5.1%～13.2%。经国家标准物质分析验证,测定值与标准值基本相符。该方法实现了在同一份溶液中同时测定金和银,与现行的石墨炉原子吸收光谱测定金、发射光谱测定银的方法相比,称样量达到10 g,样品的代表性显著增加,提高了准确度和精密度,简化了金银分析的程序,化学试剂用量少,分析成本低。     

氢化物发生-原子荧光光谱法测定土壤样品中不同价态的硒

采用氢化物发生-原子荧光光谱法( HG - AFS)测定土壤样品中Se(Ⅳ)和Se(Ⅵ)时,提取剂的选择是技术的关键.以往的提取剂种类多且不具有针对性,本文对比了不同提取剂的提取能力,确定使用KH2PO4 - K2HPO4溶液(pH=8.5)为实验用提取剂,以6 mol/L HCl作为还原剂,沸水浴30 min后HG - AFS测定Se总量,不加热直接测定Se(Ⅳ)含量,以差减法得出Se(Ⅵ)含量.在本实验酸度条件下,加入三价铁盐,可消除共存元素的干扰.方法回收率为90.0％ ～ 112.5％,线性范围为0.00 ～6.00 μg/L,相对标准偏差为5.0％ ～ 12.6％ (n=11),方法检出限可达到0.347 μg/L.标准物质的测定值与标准值相符.实验证实此方法提取效果好,是测定土壤样品中硒不同价态的可行性方法.     

ICP-MS分析地球化学样品的过程控制

通过对影响分析结果质量的消解方式、称样量、消解器皿及环境等因素进行分析,并采取相应措施,保证了分析结果的准确性、检出限,提高分析数据的重现性。