三苯基膦泡沫塑料富集火焰原子吸收分光光度法测定微量银

试样经王水分解,在5％—15％的王水介质中,用三苯基膦泡沫塑料对微量银进行分离富集。用ρ为20g/l的硫脲溶液解脱被吸附在泡沫塑料上的银。解脱液在原子吸收分光光度计上测定银量。方法的检出限为0.022×10~(-■),特征浓度为0.014μg/ml,可测定地质样品中0.0X×10~(-6)以上的银量。     

Possible evidence for a variable fine-structure constant from QSO absorption lines: systematic errors

Comparison of quasar (QSO) absorption spectra with laboratory spectra allows us to probe possible variations in the fundamental constants over cosmological time-scales. In a companion paper we present an analysis of Keck/HIRES spectra and report possible evidence suggesting that the fine-structure constant, α , may have been smaller in the past:     over the redshift range     . In this paper we describe a comprehensive investigation into possible systematic effects. Most of these do not significantly influence our results. When we correct for those which do produce a significant systematic effect in the data, the deviation of     from zero becomes more significant. We are led increasingly to the interpretation that α was slightly smaller in the past.     

离子交换树脂富集分离、火焰原子吸收光度法测定地质样品微量金

试验了四十多种常见存元及贵金属元素对富集和测定的影响。拟定了一个灵敏、快速、准确、成本低廉的地质样品中微量金的测定方法。结果令人满意，本法适用于一般地质样品中w(Au)/10^-6;0.05-50的测定。     

原子吸收法测定炼银炉渣中的金

采用HF－H2SO4除硅，萃取－原子吸收法测定炼银炉渣中的金。样品加标回收率为92.0％－104.0％，相对标准偏差为3.8％（n＝11）。将该法应用到炼银炉渣中金的测定，结果符合分析质量要求。     

NK8310螯合树脂分离富集地质样品中痕量金银铂钯及其测定

研究了硫脲螯合树脂（NK8310）分类富集地质样品中痕量Au、Ag、Pt和Pd的实验条件。在φ=10％的王水介质中，[AuCI4]^-、[AgCI2]^-、[PtCI6]^2-和[PdCI4]^2-定量吸附于树脂上并与大量贱金属分离；用5g/L硫脲－0.12mol/L HCI溶液洗脱Au、Ag、Pt和Pd，回收率为97％－104％。用硫镍矿管理样以及国家一级标准物质进行分析验证，分析结果与推荐值及标准值吻合，表明NK8310螯合树脂适用于地质样品中Au、Ag、Pt和Pd的分离富集。     

用火焰原子吸收光谱法连续测定银、铜、锌

试样经NH4F,HCl,HNO3分解的酸性介质中,选用NaCl做配合剂,Ag,Cu,Zn可以同时进入溶液。但由于上机测定时背景吸收严重,而所使用的原子吸收分光光度计不能扣除背景。选用硫脲做配合剂时,可使Ag生成稳定无色的Ag[CS(NH2)2]Cl配合物,从而避免溶液中生成AgCl沉淀,同时也使测定时的酸度得到有效的降低。原来需要分别取样、溶解和测定Ag,Cu,Zn的操作,得以在同一份样品中完成。用火焰原子吸收分光光度计连续测定Ag,Cu,Zn,方法的测定范围分别为Ag0 n×10-6～5000 0×10-6;Cu0 00n%～n 000%;Zn0 00n%～n 000%。     

Selectivity of various types of salt-resistant plants for K over Na

Selectivity by whole plants for K⁺ over Na⁺ in three types (salt excluding, salt secreting and salt diluting) of salt-resistant plants was investigated. An estimating formula of Selective Absorption (SA) capacity of root systems was derived; the Selective Transport (ST n) capacities between K⁺ and Na⁺ by various parts of the three types of plants were compared. The results showed that the SA value of salt-excluding plants were higher than that of salt-secreting and salt-diluting plants, the ST1 (root:stem) value was much higher, indicating that both the capacity of selective absorption and the capacity of selective transport by root systems were strong. In salt-secreting plants, the SA value lay between salt-diluting and salt-excluding plants, while the ST1 value was the lowest, indicating that the majority of Na⁺ uptake by root systems was transported up to their aerial parts and then the surplus salt was secreted in salt glands. In salt-diluting plants, the SA value was the lowest, indicating that the majority of Na⁺ taken up by the root systems entered into plant body perhaps to satisfy the requirements for osmotic adjustment and growth, and the ST1 value lay between salt-secreting and salt-excluding plants. These data strongly indicate that the SA and ST1 values reflect the K⁺ and Na⁺ selectivity characteristics of salt-resistant plants. Therefore, the various types of salt-resistant plants would be classified by using the values of SA and ST1. We suggest that this provides a way for distinguishing various types of salt-resistant plants. Comparing the ST n values of the six species in our paper, we concluded that the selectivity of transporting K⁺ over Na⁺ into the actively photosynthesizing organs and particularly into the developing ears is extremely high. Our conclusion is in accordance with previous results that demonstrate that the capacities of selective transport by different parts of the plant for K⁺ over Na⁺ are best quantified by ST n values. The necessity, feasibility and wide-ranging applicability of the formulas for estimating SA and ST n values have been discussed in detail.     

Characterization of NH4-phlogopite (NH4) (Mg3) [AlSi3O10] (OH)2 and ND4-phlogopite (ND4) (Mg3) [AlSi3O10] (OD)2 using IR spectroscopy and Rietveld refinement of XRD spectra

 A synthesis technique is described which results in >99% pure NH₄-phlogopite (NH₄) (Mg₃) [AlSi₃O₁₀] (OH)₂ and its deuterium analogue ND₄-phlogopite (ND₄) (Mg₃) [AlSi₃O₁₀] (OD)₂. Both phases are characterised using both IR spectroscopy at 298 and 77 K as well as Rietveld refinement of their X-ray powder diffraction pattern. Both NH₄ ⁺ and ND₄ ⁺ are found to occupy the interlayer site in the phlogopite structure. Absorption bands in the IR caused by either NH₄ ⁺ or ND₄ ⁺ can be explained to a good approximation using T_d symmetry as a basis. Rietveld refinement indicates that either phlogopite synthesis contains several mica polytypes. The principle polytype is the one-layer monoclinic polytype (1M), which possesses the space group symmetry C2/m. The next most common polytype is the two-layer polytype (2M ₁ ) with space group symmetry C2/c. Minor amounts of the trigonal polytype 3T with the space group symmetry P3₁12 were found only in the synthesis run for the ND₄-phlogopite. Electron microprobe analyses indicate that NH₄-phlogopite deviates from the ideal phlogopite composition with respect to variable Si/Al and Mg/Al on both the tetrahedral and octahedral sites, respectively, due to the Tschermaks substitution ^VIMg²⁺+^IVSi⁴⁺↔^VIAl³⁺+^IVAl³⁺ and with respect to vacancies on the interlayer site due to the exchange vector ^XII(NH₄)⁺+^IVAl³⁺↔^XII□+^IVSi⁴⁺. Received: 30 August 1999 / Accepted: 2 October 2000