雾化进样石墨炉原子吸收光谱法的研究 Ⅰ.直接雾化进样装置及其性能

介绍一种自行设计和加工的直接雾化石墨炉进样装置的结构、工作原理和操作方法。该装置由微机控制与石墨炉加热程序同步工作,可以实现自动控制和自动测量。对雾化进样石墨炉分析的仪器参数和实验条件进行了研究和选择。结果表明,该装置与石墨炉结合具有自动化程度高、重现性好、样品利用率高和分析速度快等特点。     

电感耦合等离子体发射光谱法同时测定玻璃中铝钙铁钾镁钠钛硫

通过选择分析谱线、处理样品方法和消除干扰因素等实验,建立了电感耦合等离子体发射光谱法同时测定玻璃中的Al2O3、CaO、Fe2O3、K2O、MgO、Na2O、TiO2和SO3的方法,克服了利用常规化学法测定玻璃中各氧化物步骤繁琐、耗时长、工作量大的不足。方法的回收率为95.0%~103.0%,精密度(RSD,n=10)为0.20%~1.72%。方法具有快速、简便、线性范围宽等优点,分析误差满足常规化学分析法的要求。用于钠钙硅玻璃及其制品的分析,结果令人满意。     

氢化物发生-原子荧光光谱法直接测定地球化学样品中痕量碲

采用硝酸-氢氟酸-高氯酸溶解样品,以Fe3+作减缓剂,不需分离富集,用氢化物发生-原子荧光光谱法直接测定地球化学样品中痕量碲。对测定介质、KBH4浓度、铁盐的作用等条件进行试验。方法检出限为0.0031μg/g,精密度(RSD,n=11)<6.10%。方法用于国家一级地球化学标准物质中痕量碲的测定,结果与标准值一致。     

纺织品中偶氮染料还原液内芳香胺的电喷雾电离质谱分析

在优化的条件下,用电喷雾电离质谱(ESI-MS)检测了多种纺织品中由偶氮染料还原获得的芳香胺。当毛细管温度为100℃、鞘气流速为25单位、进样流速为10μL/min、电压为5kV时,信号的总离子流强度高且较稳定。实验分析了19种致癌芳香胺标准溶液的二级质谱,获得了相应物质的特征碎片离子;在此基础上,建立了基于ESI-MS对毛巾、棉布等样品中芳香胺进行快速定性分析的方法,具有灵敏度高、特异性好、检测速度快等优点。     

能量色散X射线荧光光谱法测定钼矿石中钼铅铁铜

建立了能量色散X射线荧光光谱法测定钼矿石中钼、铅、铁、铜的方法,讨论了粒度效应、矿物效应的影响因素,确定了采取粉末样品,用系列标准样品建立工作曲线,通过元素间相互校正消除基体效应,用内控标准样品考察了方法的精密度(RSD,n=11)为0.44%～15.4%。实际样品的测定结果和化学法相符,可满足日常分析工作需要。     

碱消解-高效液相色谱-电感耦合等离子体质谱法测定生物样品中的甲基汞和乙基汞

建立了碱消解-高效液相色谱-电感耦合等离子体质谱联用系统测定生物样品中甲基汞(MeHg)与乙基汞(EtHg)的分析方法。为提高灵敏度,选用微流量的PFA雾化器,在优化的检测条件下,MeHg及EtHg检出限可达到0.036μg/L和0.03μg/L;线性范围达到4个数量级,两条工作曲线线性相关系数为1。对1.78μg/L MeHg、1.65μg/L EtHg的混合标准溶液重复测定7次,色谱峰面积的相对标准偏差(RSD)分别为1.79%和1.44%。对标准物质BCR 464(金枪鱼)的分析结果表明,测定值与标准值基本吻合,但略低于标准值;甲基汞和乙基汞的加标回收率分别为85.9%和84.5%。高效液相色谱与质谱联用技术的高灵敏度和低检出限能够满足生物样品中汞形态定量分析的要求。     

等离子体质谱法测定玄武岩中微量元素三种样品预处理方法的比较

在测定玄武岩的微量元素时,为了保证得到的微量元素结果反映源区特征,需经预处理去除玄武岩的孔洞中充填的碳酸盐等物质。选取雷州半岛新生代玄武岩三个样品,每一个样品用三种预处理方法进行预处理,等离子体质谱法测定其中的微量元素。分析结果表明,用稀硝酸浸泡样品,会导致玄武岩中大多数微量元素严重丢失,得到的数据失真;而用稀盐酸浸泡去除碳酸盐的方法基本不改变玄武岩中微量元素的含量。     

Sulfur isotope measurement of sulfate and sulfide by high-resolution MC-ICP-MS

We have developed a technique for the accurate and precise determination of ³⁴S/³²S isotope ratios (δ³⁴S) in sulfur-bearing minerals using solution and laser ablation multiple-collector inductively coupled plasma mass spectrometry (MC-ICP-MS). We have examined and determined rigorous corrections for analytical difficulties such as instrumental mass bias, unresolved isobaric interferences, blanks, and laser ablation- and matrix-induced isotopic fractionation. Use of high resolution sector-field mass spectrometry removes major isobaric interferences from O₂⁺. Standard-sample bracketing is used to correct for the instrumental mass bias of unknown samples. Background on sulfur masses arising from memory effects and residual oxygen-tailing are typically minor (< 0.2‰, within analytical error), and are mathematically removed by on-peak zero subtraction and by bracketing of samples with standards determined at the same signal intensity (within 20%). Matrix effects are significant (up to 0.7‰) for matrix compositions relevant to many natural sulfur-bearing minerals. For solution analysis, sulfur isotope compositions are best determined using purified (matrix-clean) sulfur standards and sample solutions using the chemical purification protocol we present. For in situ analysis, where the complex matrix cannot be removed prior to analysis, appropriately matrix-matching standards and samples removes matrix artifacts and yields sulfur isotope ratios consistent with conventional techniques using matrix-clean analytes. Our method enables solid samples to be calibrated against aqueous standards; a consideration that is important when certified, isotopically-homogeneous and appropriately matrix-matched solid standards do not exist. Further, bulk and in situ analyses can be performed interchangeably in a single analytical session because the instrumental setup is identical for both. We validated the robustness of our analytical method through multiple isotope analyses of a range of reference materials and have compared these with isotope ratios determined using independent techniques. Long-term reproducibility of S isotope compositions is typically 0.20‰ and 0.45‰ (2σ) for solution and laser analysis, respectively. Our method affords the opportunity to make accurate and relatively precise S isotope measurement for a wide range of sulfur-bearing materials, and is particularly appropriate for geologic samples with complex matrix and for which high-resolution in situ analysis is critical.     

<Superscript>226</Superscript>Ra, <Superscript>232</Superscript>Th and <Superscript>40</Superscript>K activities in soils of Cuihua Mountain National Geological Park,China

Gamma activity from the naturally occurring radionuclides namely, ²²⁶Ra, ²³²Th, the primordial radionuclide ⁴⁰K was measured in the soil of Cuihua Mountain National Geological Park, China using γ-ray spectrometry technique. The mean activity of ²²⁶Ra, ²³²Th and ⁴⁰K were found to be 27.2 ± 6.5, 43.9 ± 6.2 and 653.1 ± 127.6 Bq kg⁻¹, respectively. The concentrations of these radionuclides were compared with the typical world values and the average activities of Chinese soil. The radium equivalent activity, the air absorbed dose rate, the annual effective dose rate, and the external hazard index were evaluated and compared with the internationally approved values. All the soil samples have Ra_eq lower than the limit of 370 Bq kg⁻¹ and H _ex less than unity. The overall mean outdoor terrestrial gamma dose rate is 66.3 nGy h⁻¹ and the corresponding outdoor annual effective dose is 0.081 mSv.     

Si diffusion in zircon

Self-diffusion of Si under anhydrous conditions at 1 atm has been measured in natural zircon. The source of diffusant for experiments was a mixture of ZrO₂ and ³⁰Si-enriched SiO₂ in 1:1 molar proportions; experiments were run in crimped Pt capsules in 1-atm furnaces. ³⁰Si profiles were measured with both Rutherford backscattering spectrometry (RBS) and nuclear reaction analysis with the resonant nuclear reaction ³⁰Si(p,γ)³¹P. For Si diffusion normal to c over the temperature range 1,350–1,550°C, we obtain an Arrhenius relation D = 5.8 exp(−702 ± 54 kJ mol⁻¹/RT) m² s⁻¹ for the NRA measurements, which agrees within uncertainty with an Arrhenius relation determined from the RBS measurements [62 exp(−738 ± 61 kJ mol⁻¹/RT) m² s⁻¹]. Diffusion of Si parallel to c appears slightly faster, but agrees within experimental uncertainty at most temperatures with diffusivities for Si normal to c. Diffusion of Si in zircon is similar to that of Ti, but about an order of magnitude faster than diffusion of Hf and two orders of magnitude faster than diffusion of U and Th. Si diffusion is, however, many orders of magnitude slower than oxygen diffusion under both dry and hydrothermal conditions, with the difference increasing with decreasing temperature because of the larger activation energy for Si diffusion. If we consider Hf as a proxy for Zr, given its similar charge and size, we can rank the diffusivities of the major constituents in zircon as follows: D _Zr < D _Si << D _{O, dry} < D _{O, ‘wet’}.