磷酸三丁酯萃淋树脂色层分离电感耦合等离子体质谱法测定富稀土样中微量铀和钍

研究了磷酸三丁酯萃淋树脂色层分离,电感耦合等离子体质谱法测定富稀土样中微量铀、钍的方法。样品经消解后,以磷酸三丁酯萃淋树脂为固定相、8 mol/L硝酸为流动相过柱分离,样品中的大部分稀土元素随流动相流出,而铀和钍则被固定相吸附,用去离子水洗脱后,再用电感耦合等离子体质谱仪测定。铀、钍的检出限分别为0.06,0.16μg/L,测定结果的相对标准偏差均小于10%(n=5),加标回收率为98%~105%。对稀土矿石标准物质进行测定,测定值与推荐值相符。该法操作简便,测定结果可靠,适于富稀土样中微量铀、钍的测定。     

微色谱柱分离/ICP-AES测定环境样品中的痕量硼

本文采用色谱系统对水样品（温泉水、卤水）中的硼进行分离富集，探讨了影响其分离富集的条件。实验表明，在pH＝8条件下，硼可被树脂完全吸附，用3mL 1mol/L硫酸可以从吸附术上完全解吸硼，浓缩物用ICP－AES进行测定，所建立的方法简便、准确，适合于含盐量高及其它水样品中微量硼的测定。     

氨丙基硅三烷改性介孔二氧化硅及对痕量镉(Ⅱ)的分离富集性能研究

以氨丙基硅三烷作为改性剂,对介孔二氧化硅表面进行修饰,制备了氨基化介孔二氧化硅吸附材料,采用透射电镜和傅立叶红外光谱仪对其进行表征,并用于水样中痕量镉的富集,建立了氨基化介孔二氧化硅分离预富集/火焰原子吸收光谱法测定痕量镉的方法。考察了溶液pH值、样品流速、洗脱剂类型、干扰离子和吸附容量等对痕量镉分离富集的影响,以及该吸附材料对痕量镉(Ⅱ)的吸附性能。结果表明,溶液pH 7.0,样品流速8 m L/min时镉离子能被制备材料高效吸附,吸附的镉(Ⅱ)用5.0 m L 2 mol/L HNO_3完全洗脱,火焰原子吸收法测定。在最佳实验条件下,方法的线性范围为0.6~20 ng/m L,定量下限为0.5 ng/m L,富集倍数为50倍,对10 ng/m L Cd2+测定的相对标准偏差(n=11)为0.92%,加标回收率为98.8%~104.5%。该方法的抗干扰能力较好,富集柱可循环使用12次以上,可用于环境水样中镉(Ⅱ)的测定。     

CL-7301微色谱柱分离铀化合物中痕量镉的方法研究

采用CL-730l树脂微色谱柱研究了铀化合物中基体铀和痕量镉的分离条件,并用在线富集法测定了铀化合物中的痕量镉.通过试验选择0.125mol/L的HI酸介质中,镉的吸附率接近100%,而铀不被吸附,分离效率达到99.9%以上.吸附在柱上的镉用10 g/L EDTA 洗脱,原子吸收光度法测定.利用在线富集技术,镉的检出限降低至2.3μg/L.对八氧化三铀和分析纯醋酸双氧铀样品中痕量镉进行测定,方法精密度为1.5%,加标回收率为96%～98%.     

顺序注射-样品预处理模块系统-电热原子吸收法测定海水中痕量铜

将样品预处理模块与自动化顺序注射系统相结合,建立了未经稀释的海水中痕量铜的分离富集方法。铜-PDC螯合物在样品预处理模块中被吸附在聚四氟乙烯微珠填充柱上,用少量甲醇洗脱后,将洗脱液引入电热原子吸收中测定。进样体积为1.0mL时,富集倍率为20,检出限为0.015μg/L,采样频率为26次/h,线性范围为0.05~1.00μg/L,相对标准偏差(RSD)为1.8%(0.50μg/L)。利用本方法分离富集并测定了标准海水样品NASS-5及近海水样中的铜含量,并进行了加标回收实验。     

流动注射微柱预富集等离子体原子发射光谱法测定高纯锌中痕量稀土元素

本文报道以DCS-偶氮胂固定于活性炭上作为固定相,用于流动注射微柱预富集体系和等离子体原子发射光谱测定痕量稀土元素.测定了吸附材料对稀土元素的静态和动态吸附容量,分别达几十和几个mg/g吸附材料;对影响柱预富集的PH、上柱速度、洗脱酸度、柱尺寸等因素进行了详细考察;在优化条件下,富集倍数为10倍左右.对La、Nd、Eu、Gd、Tb、Dy、Ho和 Lu等元素的检出限为 μg/L级,RSD在 1.5％～3.9％之间(n=6,单一稀土浓度0.085 mg/L).该法应用于高纯锌中痕量稀土元素的测定,试样加入回收率在 84.5％～97.6％之间,分析结果满意.     

聚苯乙烯苄基膦酸离子交换树脂分离偶氮胂Ⅲ光度法测定岩矿中的钍

南开大学何炳林教授等研制成功新型树脂——大孔膦酸树脂。资料介绍这类树脂可在分析方面应用,但国内未见有关报导。我们利用其中一个系列,聚苯乙烯苄基膦酸树脂对钍的交换分离作了工作。将样品制成4N盐酸溶液后上柱,钍被树脂完全吸附而与共存离子分离,用4％草酸铵解吸钍后,偶氮胂Ⅲ光度法测定。方法用于测定多种类型岩矿中钍,结果较满意。 1.仪器与试剂: (1)721型分光光度计。 (2)钍标准溶液,20微克/毫升,4N盐酸介质。     

三乙烯四胺修饰β-环糊精交联树脂分离富集/原子吸收法测定大米中的铅、镉

该文制备了一种新型吸附材料三乙烯四胺修饰β-环糊精交联树脂(TETA-β-CDP),并对其进行红外光谱表征,优化了该吸附材料对痕量铅、镉的吸附和解析条件,建立了动态条件下同时分离富集/原子吸收光谱测定大米中铅和镉的新方法。在p H 5.5时,样品溶液以1.0 m L/min流速过柱,试液中的Pb2+和Cd2+可被该树脂定量富集,其动态饱和吸附容量分别为22.8,31.3 mg/g,吸附在TETA-β-CDP上的Pb2+和Cd2+可用0.1 mol/L HCl以0.8 m L/min流速完全洗脱。该方法对铅、镉的检出限(3σ,n=11)分别为0.038 mg/L和0.016 mg/L;线性范围分别为0.2~20 mg/L和0.05~2.5 mg/L;相对标准偏差(RSD)分别为2.8%和1.7%;加标回收率分别为97.5%~101.0%和95.0%~102.5%。该方法用于大米样品中痕量铅、镉的测定,结果满意。     

土壤对外源钍的吸附行为表征

外源钍对土壤的污染风险和程度取决于钍在土壤中的吸附行为. 以包头稀土工业区土壤样品和土壤环境矿物组分为研究对象, 通过静态吸附方法研究外源钍在土壤样品和环境矿物组分(高岭土、蒙脱土、碳酸钙、水合氧化铁/锰和腐殖酸)上的吸附, 并对吸附行为进行了表征. 结果表明, 土壤样品对外源钍有很强的吸附能力, 对加入的外源钍(10^-4 mol/L)吸附率在97%以上; 土壤环境矿物组分对加入的外源钍(1 g/L)吸附率在28%～46%之间. 通过扫描电镜-能谱(SEM-EDS)分析可知, 外源钍进入土壤后与矿物组分发生相互作用, 可能形成了稳定化钙质钍碳酸盐和钍磷酸盐; 傅里叶变换红外光谱(FTIR)分析表明, 钍是与土壤环境矿物组分上的活性吸附位点发生相互作用而吸附并保持在土壤中, 是物理吸附和化学吸附共同作用的过程; X射线衍射分析(XRD)表明, 土壤在吸附钍前后, 其矿物组分基本相同, 而矿物晶体相态发生明显变化. 由于不同土壤矿物组分对钍的吸附方式不同, 导致吸附的钍以不同形态存在于土壤中.     

在线富集离子色谱-质谱联用法同时测定饲料添加剂中的16种有机酸

建立了在线富集方式结合离子色谱-质谱(IC-MS)快速分离分析16种有机酸的方法。离子色谱配备自制富集柱和分离柱对有机酸进行在线富集和分离;质谱采用大气压化学电离源负离子电离方式(APCI^-),在选择离子监控(SIM)模式下对有机酸进行定性和定量分析。采用200 μL大体积进样,在线富集时间为3 min,以NaOH溶液作为淋洗液,梯度洗脱。结果表明,富集柱和分离柱对有机酸有很好的富集分离能力;16种有机酸在30 min内完全洗脱,并在一定浓度范围内线性关系良好;方法检出限(LODs)为0.01~0.22 mg/L;加标回收率为70.6%~110.8%,相对标准偏差(RSD)≤6.3%。该方法样品前处理简单,分离速度快,有机酸检测灵敏度高,适用于多种饲料添加剂样品中有机酸添加剂的检测。     

Accurate determination of trace amounts of thorium in silicate rocks by cation-exchange chromatography and spectrophotometry

Thorium in four of the South African NIMROC standards and in four secondary standards is determined accurately by means of spectrophotometry with arsenazo-III after a selective cation-exchange separation on an AG50W-X4 resin column. All other elements are eluted with 6 M hydrobromic acid before the final elution of thorium with 5 M nitric acid. Small amounts of zirconium which may be present in the thorium eluate, are effectively complexed with oxalic acid which also eliminates the spectrophotometric interferences caused by organic material leached from the resin column. The accuracy and precision of the method are demonstrated by the analysis of synthetic mixtures containing various amounts of thorium. Amounts of 10 and 100 μg of thorium can finally be determined with coefficients of variation of 1% and 0.2%, respectively.     

Complexometric determination of thorium in ThO2−PuO2

A method based on the complexometric titration of thorium using ethylene diaminetetra-acetic acid (EDTA) as complexant has been developed for the determination of thorium in thorium-plutonium solution without resorting to prior separation of plutonium. Plutonium in the form of Pu(VI) does not affect the thorium determination when present up to 10% in thorium—plutonium solution. For oxidation of plutonium to Pu(VI), HClO₄ or AgO was used. HClO₄ is preferred. The thorium values obtained without prior separation of plutonium are compared with those obtained after separating plutonium by anion exchange technique. A precision of ±0.5% has been obtained for 5–10 mg of thorium in the aliquot.     

Separation of thorium by anion-exchange chromatography in malic acid media

Summary Systematic studies on the anion-exchange behaviour of thorium in malic acid solution on Amberlite IRA-401 have been carried out. Acids such as HNO₃, HCl, H₂SO₄, HClO₄ and salts such as NH₄Cl, (NH₄)₂SO₄, NaClO₄, NaCl and NaNO₃ have been tested as eluants for thorium, their efficiency being evaluated in terms of their distribution coefficients. HNO₃ is the best eluent for thorium. Methods have been developed for the separation of thorium from several elements in malic acid media using selective adsorption or selective elution. The proposed method is applied to the analysis of thorium in monazite where HClO₄ is a better eluant than HNO₃. The method is simple and the accuracy about ±3%.     

Determination of uranium in thorium matrixes by epithermal neutron activation analysis

Uranium in thorium matrixes or in minerals and ores containing thorium is determined by epithermal neutron activation analysis (ENAA). In some minerals and ores, such as monazite sands, the analysis can be carried out by purely instrumental means with no chemical separation of uranium or thorium from the irradiated matrix. For thorium compound matrixes with very low uranium contents, a rapid radiochemical separation method, based on the retention of uranyl ion on anion-exchange resins, is first carried out, before counting the gamma-ray peaks for²³⁹U in multichannel analysers coupled to NaI(Tl) scintillators or to Ge(Li) detectors.     

Determination of traces of rare earths in high-purity thorium dioxide by neutron activation analysis

The use of thorium dioxide as a nuclear fuel requires the determination of individual rare earth impurities at 0.08–1 mg kg^?1 levels. Neutron activation is sufficiently sensitive but separation from the matrix is essential. In the proposed method, thorium dioxide (5–20 g) is dissolved in concentrated nitric acid with a little hydrofluoric acid; after evaporation, thorium is complexed with ammonium carbonate and the solution is passed through a small column of Chelex-100 resin which retains the rare earths quantitatively without retaining thorium. The rare earth elements are eluted with dilute nitric acid, concentrated, and irradiated with standards; after irradiation the rare earth are collected on a lanthanum carrier and measured by γ-ray spectrometry. The recoveries of rare earths were checked with tracers and by standard addition to thorium dioxide matrices. The reproducibility for La, Eu and Dy was satisfactory at 0.01, 0.003 and 0.002 mg kg^?1, respectively; as was the reproducibility for all rare earths added to thorium dioxide (1–4 μg/5 g). Limits of detection are adequate for certification of nuclear-grade material.     

Thorium determination in aqueous solutions after separation by ion-exchange and liquid extraction

The concentration of thorium in aqueous samples has been determined by means of alpha-spectroscopy and UV?CVis photometry after chemical separation and pre-concentration of the actinide by cation exchange and liquid-liquid extraction using Chelex-100 resin and 30%TBP in dodecan, respectively. Method calibration was performed using thorium standard solutions and resulted in a high chemical recovery for cation exchange and liquid extraction. Regarding, the effect of physicochemical parameters (e.g., pH, salinity, competitive cations, and colloidal species) on the separation recovery of thorium from aqueous solutions by cation exchange has also been investigated. The investigation was performed to evaluate the applicability of cation exchange and liquid extraction as separation and pre-concentration methods prior to the quantitative analysis of thorium in water samples, and has shown that the method could be successfully applied to waters with relatively low-salinity and metal ion contamination.     

Determination of U and Th in tungsten by radiochemical neutron activation analysis

A radiochemical separation method using an anion exchange resin has been applied to 4N grade tungsten for determining U, Th and 4 other elements. While tungsten remained in the resin, Na, K and As were separated with 0.05M HCl and 1M HF and then U, Th and Cr were eluted with 1M HCl and 1M HF. The separation yield of neptunium (U) was influenced largely by the amount of thorium, but this influence could be neglected as the concentration of the thorium was below 0.5g/ml. The content of these elements were calculated by a single comparator method using monitors, gold and cobalt. The detection limits of U and Th are 4.0 and 1.2 ppb, respectively.     

Column chromatographic separation of thorium(IV) from ascorbic acid medium using poly-(dibenzo-18-crown-6)

A simple separation method has been developed for thorium(IV) using poly-(dibenzo-18-crown-6) and column chromatography. The separation was carried out from ascorbic acid medium. The adsorption of thorium(IV) was quantitative from 0.001-0.01M ascorbic acid. The elution of thorium(IV) was quantitative with 4.0-8.0M HCl, 3.0-6.0M HClO₄, 4.0-8.0M H₂SO₄ and 1.0-8.0M HBr. The capacity of poly-(dibenzo-18-crown-6) for thorium(IV) was found to be 1.379±0.01 m^.mol/g of crown polymer. Thorium(IV) was separated from a number of cations in binary as well as in multicomponent mixtures. The method was extended to the determination of thorium in monazite sand. It is possible to separate and determine 5 ppm of thorium(IV) by this method. The method is very simple, rapid, selective and has good reproducibility (approximately ±2%).     

Studies on extraction of thorium by the N-oxides of 5-(4-pyridyl)nonane and trioctylamine from different mineral acid solutions and its separation from rare earth elements and yttrium

The N-oxides of 5-(4-pyridyl)nonane and trioctylamine have been evaluated for use in the extraction of thorium from different mineral acid solutions. The influence of the concentration of the solvents and salting-out agents has been investigated. The possible mechanism of extraction is discussed in the light of the results of extraction isotherms, loading-ratio data and log-log plots of reagent concentration vs. distribution ratio. Separation factors for a number of metal ions are reported and a method for the separation of thorium from rare earth elements and yttrium is also suggested.     

Development of selective separation method for thorium and rare earth elements from monazite liquor

The present work succeeded to develop new optional procedures to enhance the separation process of thorium and REEs. Selective precipitation of thorium with pyrophosphate was successfully attained for the upscale level in which, complete and efficient thorium separation (99%) was achieved with relatively low co-precipitation of REEs (average 15%) and Fe(III) (2.6%). On the other hand, promising and costless method has been developed to optimize the selective precipitation of REEs by adjusting the ratio of the free acids H₂SO₄ to H₃PO₄ at 5:1. It could be obviously demonstrated that about 65.3% of LREEs could be precipitated with a minor amount of thorium 11.9%. Finally, this proposed method could be successfully applied for production of Th and REEs with relatively high yield and purity in addition to low-cost–benefit.