Determination of thallium in ore samples from Allchar by atomic absorption spectrometry

The concentration of thallium was determined in samples from the Allchar deposit by flame and flameless atomic absorption spectrometry. Interferences of various elements were investigated. A concentration of 10–2000 ppm was found in samples from Allchar ore.     

中江丹参植株中Pb含量和茎叶中Pb的形态分析

为了解Pb在丹参植株中的含量分布和在茎叶中的存在形态,采用氢化物发生原子荧光法测定来自于中江县丹参种植基地的6个丹参植株和对应土壤样品中的Pb含量,对茎和叶中Pb的初级和次级形态进行分析。结果表明:Pb在根、茎、叶和土壤中的含量分别为0.28±0.05、4.30±0.54、6.22±0.52和16.95±3.14(mg/kg),Pb在丹参植株中表现出从上至下含量依次减少的分布规律,植株对Pb有很强的转移能力,其转移系数达到14-26。茎和叶中Pb的沸水浸出率分别为40.2%和47.9%,浸出Pb中60%以上为可透过0.45μm滤膜的可溶态,可溶态中约80%的铅以无机态形式存在。     

铅芯浓度仪校准方法的研究

铅芯浓度仪主要用于测鼍铅芯的浓度,其量值是否准确可靠决定了铅芯的质量好坏.参考白度计的校准方法对铅芯浓度仪的校准方法进行了研究.在测试中,校准铅芯浓度仪所用的标准灰板采用了校准光谱测色仪所用的一套标准灰板,校准时的标准值取溯源证书中的波长450nm的蓝光漫反射辐亮度因数计算而来.从铅芯浓度仪对标准灰板的测试,以及对校准结果的测量不确定度的评定表明,该校准方法合理,实验数据准确可靠.     

Local electron density models for Tl to Pb conversion in lorandite

The nuclear conversion of ²⁰⁵Tl to ²⁰⁵Pb by neutrino capture, lorandite (TlAsS₂) converts into Pb-bearing lorandite (Tl_1−xPb_xAsS₂) where x is a very small number.Having used a highly simplified cluster model of lorandite, we intended to calculate the electron density of Tl and its neighbouring atoms by the quantum chemical discrete variational method [5,6].Substituting Pb for Tl in the lattice site of Tl and calculating the difference existing between these two clusters, we would like to discuss the possible changes of the cluster's stability and the relative binding between TlS and PbS in lorandite.     

The possibility of concentrating thallium minerals from the Allchar deposit

Thallium belongs to the very rare elements and lack of knowledge of its distribution has been due to difficulties in its estimation [1]. Approximately, thallium is represented in the Earth's core by 3×10⁻⁴% [2]. It seldom forms its own minerals. Usually, it can be concentrated as a by-product in sulphide mineral concentrates, which can be obtained by both gravitation, flotation, magnetic and electro-concentration methods. Thallium can be further extracted by chemical and metallurgical processes [3].     

氢化物原子荧光法测定味精中铅

该文讨论了氢化物原子荧光法测定味精样品中的铅,结果表明,样品经水直接溶解后,在30g.L-1硼氢化钾(KBH4)还原剂介质和5g.L-1氢氧化钾溶液中,样品溶液酸度以0.24 mol.L-1为最佳。铅浓度在2~12μg.L-1范围内与荧光值呈线性,相关系数为r=0.9993。RSD小于10%,回收率为95%~102%。该法具有简便、准确、可靠、干扰少的优点。     

Thermal stability and concentration effect in erbium-doped lead fluoroborate glasses

Thermal and optical properties of lead fluoroborate glasses containing Er ions have been investigated. Glass properties of multicomponent oxyfluoride systems have been examined in two ways: with various (a) activator (Er ions) and (b) PbF₂ concentrations. Thermal stability parameter Δ T linearly decreases from 162^∘C to 138^∘C, when PbF₂ content increases from 9 to 72 wt% in glass composition. Non-linear dependence of Δ T stability parameter is observed as a function of activator concentration. The optimal highest values of Δ T factor are obtained for Er concentration in range of 0.5 ÷ 1.5 wt%. Quite intense and long-lived near-infrared photoluminescence of erbium ions at 1.55 μm related to the main ⁴I_13/2–⁴I_15/2 laser transition has been detected in lead fluoroborate glass. Photoluminescence intensity and the ⁴I_13/2 lifetime considerably increase with increasing of PbF₂ concentration. The opposite effect is observed with increasing of activator concentration, which is due to the luminescence quenching. Thus, the ⁴I_13/2 lifetime decreases and this behavior is consistent with non-radiative processes related to the Er–Er interaction increasing.     

Major and trace elements in some minerals and ore from Crven Dol,Allchar

Lorandite mineral (TlAsS₂), orpiment (As₂S₃), realgar (As₂S₂) and the ore from Crven Do, were investigated by EMPA, PIXE and NAA in order to determine major and trace elements. Lorandite is a “pure” stoichiometric mineral. Bi and Hg were not detected while the U and Th content is considerably below 1 ppm. Almost identical results were obtained for orpiment and realgar, which enables application of the latter as a “monitor” for detection of ²⁰⁵Pb originating from background reactions. The results of the ore investigation, although preliminary, indicate the possible successful mineralogical separation of lorandite.     

Crven Dol Tl deposit in Allchar: Mineralogical investigation,chemical composition of Tl minerals and genetic implications

Ore samples enriched in sulfides and sulfosalts from the Tl-rich zone (entrance no. 21) of the Allchar deposit were investigated with reflected light microscopy and scanning electron microscopy, and the phase compositions were determined quantitatively with the electron microprobe. Major phases encountered are orpiment (As₂S₃), realgar (AsS) and pyrite. Lorandite is the major Tl-bearing mineral and it was indicated as pure stoichiometric (Tl: 60.1%, As: 20.6%, S: 18.4%). No, Sb and Pb were encountered. An entirely new Tl mineral was discovered with much higher Tl-concentrations and lower As-concentrations than in lorandite (Tl: 74.09%, As: 9.67%, Sb: 0.42%, S: 16.66%). The presence of this mineral as the last mineralization episode presents for the first time unequivocal evidence for a drastic enrichment of the ore-bearing fluids in Tl in the youngest stage.     

Seasonal variations of lead concentration and loading rates in residential house dust in northern Idaho

Although lead hazards to humans have been known since ancient times and many regulatory actions and lead risk reductions have been achieved over the past century, lead contamination and exposure remain significant problems worldwide. The focus of this study was to investigate whether residential house dust lead concentrations and lead and dust loading rates in non-contaminated or "background" communities in northern Idaho are significantly affected by seasonal variations. House dust samples were obtained from 34 houses in five towns of northern Idaho from March to November 1999. There was evidence of significant seasonality of lead concentration in house dust in some towns, but no evidence in other towns. Because of the high variability between the towns and small sample sizes, it was difficult to make firm conclusions about seasonal patterns observed in house dust lead levels. A linear relationship between precipitation rates and dust loading rates was detected.     

Determination of water concentration in brain tissue by Raman spectroscopy

Brain edema is one of the most common morbidity factors in patients with intracranial neoplasms and cerebrovascular pathology. Monitoring of intracranial pressure gives only an indirect and global measure of brain swelling. We have made an assessment of the applicability of Raman spectroscopy as an alternative method for assessing brain edema, which measures the water concentration in the tissue directly. Partial least-squares models were developed on the basis of Raman spectra measured in the 2600-3800-cm(-1) region, which predict the water fraction of brain tissue in the 0.75-0.95 range, with an accuracy better than 0.01.     

Determination of lead in blood and urine by SPME/GC.

Lead is the most frequently quantitated toxic metal in biological matrixes. In this paper, a method is described for lead determination in whole blood and urine using solid-phase microextraction (SPME) gas chromatography. Lead ion is first derivatized with sodium tetraethylborate to form tetraethyllead, which is then extracted from the headspace over the sample by SPME. The analytical procedure was optimized for coating selection, pH, extraction time, and effect of salt. The relative standard deviation was less then 10% for both urine and blood samples. The limit of detection was 3 and 4 ppb; the limit of quantification is 5 and 10 ppb for urine and blood samples, respectively. Good linearity was found for both urine and blood samples when PDMS coating was used. The standard addition method was used for quantitation. Certified urine and blood samples were analyzed, and good accuracy was obtained.     

活性炭动态吸附ICP-AES法测定粗铅中的金

该文建立活性炭动态吸附-电感耦合等离子发射光谱测定粗铅中金的方法。通过实验确定粗铅样品的取样方法,采用硝酸-王水溶样-活性炭动态吸附富集金,这一过程可实现共存干扰元素的分离;灼烧灰化,以王水溶解金定容。在选定的仪器工作条件下采用电感耦合等离子体发射光谱(ICP-AES)测定其中的金含量。结果表明,方法检出限为0.066μg/g,标准加入回收率为96.0%～104.0%,相对标准偏差(RSD)为1.03%～4.01%,具有良好的准确度和精密度,测定结果与火试金测定结果吻合。该方法高效、环保,结果可靠,适用于大批量粗铅样品的测定。