表面活性剂在火焰原子吸收光谱法中增感效应的研究

表面活性剂在火焰原子吸收光谱法中的应用及理论研究目前非常活跃,但表面活性剂对元素产生增感效应的原因尚未弄清,本文研究了不同类型表面活性剂对元素吸光度值的影响,发现除碱金属元素外,表面活性剂对金属元素是否产生增感效应与元素在火焰中的原子化效率有关,进而对其增感机理做了探讨。     

相对峰吸收法测定几种元素在乙炔-空气火焰中的原子化度

本文提出以相对峰吸收法测定元素在乙炔-空气火焰中的原子化度,并讨论了方法的理论基础。采用Cu作参考元素,测定了Na、Mg、Cr和Mo等元素在乙炔-空气火焰中的原子化度。另外,还研究了火焰组成和测量高度对四种元素的吸光度的影响,以及对Na和Mg的原子化度的影响。实验表明,这两个因素对原子化度都有影响,而火焰组成的影响较大。所以,原子化度是一个相对的数值,它与测量条件有密切关系。     

悬浮液进样原子吸收光谱分析中样品的粒径效应

研究了悬浮液进样 FAAS和悬浮液进样 GFAAS中样品粒径效应。实验表明 ,悬浮液颗粒粒径 <30 μm能满足石墨炉原子化测定需要 ,而火焰原子化要求在粒径≤ 5 μm的前提下 ,再根据待测元素的性质选择合适的火焰类型 ,方能达到较满意的测定效果。     

石墨炉原子吸收光谱测硼时基体改进剂的选择

研究各种基体改进剂的增感效果,和它们对灰化、原子化温度的影响。结果表明,Ca、Sr、Ca-Mg、Ca-La、Sr-Mg均可作为硼的基体改进剂,且Ca-Mg、Ca-La、Sr-Mg较之Ca、Sr性能优越。并分别以Ca、Ca-Mg、Sr-Mg作基体改进剂,直接分析饮用水中痕量硼,所得结果基本一致,相对标准偏差均在10%以内。     

火焰原子吸收光谱法中有机试剂的增感效应

详细研究了11种有机试剂对火焰原子吸收光谱法的增感效应。通过测定这些有机试剂对Cu、Mg、Li、Na、K、Rb、Cr、Mo、Sr、Ba等金属离子吸光度的影响,得到了有机试剂增感的规律性。     

氢化物原子吸收机理的研究 Ⅰ.H_2和空气在氢化物原子化中的作用

研究了氢气和空气在氢化物原子化过程中的作用,观察到H_2的存在下不仅引发自由基过程,而且抑制氢化物的热分解.空气的存在,使一些元素氢化物的最佳原子化温度降低,其增感作用只有在H_2共存时才表现出来.在没有H_2共存时,空气可能与氢化物反应生成氧化物,对吸收信号产生抑制.     

在火焰原子吸收分光光度计上进行无火焰原子化法测定

介绍了在常规火焰原子吸收分光光度计上采用特制高温陶瓷管进行无火焰原子化测定的方法,该方法即具有常规火焰原子化法的装置简单,操作方便,稳定性好的特点,又具有无火焰原子化法高灵敏度的优点。采用此方法对铜、锌两种元素进行了测定,灵敏度比常规火焰原子化法提高了30～50倍,检出限及回收率等指标均优于常规火焰原子化光谱法,是一种高效、简便、经济、实用的原子化方法。     

在火焰原子吸收光度计上以无火焰原子化法测定碱金属元素

在常规火焰原子吸收分光光度计上采用特制的不锈钢原子化管对碱金属元素进行无火焰原子化法测定,克服了碱金属元素在火焰中的电离效应,试液用量极少。测定结果的相对标准偏差小于0.3%(n=11),回收率为98.9%~99.2%。     

甲酸盐在纳米AgBr/I粒子乳剂中的增感作用

分别以鱼明胶和骨明胶(惰胶)作为分散介质制备了两种不同形貌与粒径的纳米AgBr/I粒子乳剂.利用掺入作为正空穴捕获剂的甲酸盐,可以使本征感光度很低的纳米粒子乳剂的感光度有相当大的提高,显示甲酸盐具有很好的增感效果.对鱼明胶介质中制备的纳米AgBr/I粒子乳剂,甲酸盐掺杂方式不同其增感效果不一样.在乳剂颗粒中均匀掺杂增感效果最好,而趋向于近表面掺杂则增感效果降低,显示出甲酸盐掺杂的位置效应.籽晶掺杂后包壳的复合结构乳剂颗粒与均匀掺杂乳剂颗粒的增感效果近似.对鱼明胶介质中制备的掺杂甲酸盐的纳米AgBr/I粒子乳剂再进行硫增感或硫加金增感,乳剂感光度可进一步提高,表明甲酸盐掺杂与常规的硫增感或硫加金增感有很好的协同作用.     

增感效应火焰原子吸收光谱法测定 铁矿石中的微量铬

提出了增感效应火焰原子吸收光谱测定铁矿石中微量铬的新方法。研究了表面活性剂十二烷基硫酸钠(SDS)对铬的增感效果。增感效应可使火焰原子吸收光谱的灵敏度提高 27倍。本法已用于测定铁矿石中的微量铬,检测限为 7.0μg/L ,回收率为 91.1%～115.9%,RSD为 4.0%。     

Appraisal of different electrothermal atomic absorption spectrometric methods for the determination of strontium in biological samples

A comparative study of various potential chemical modifiers (La, Mg, Pd, Ni, Ta, Lu, Sm, Eu, Ho, Er, Tm and Tb) as well as of different background correction procedures (deuterium and Zeeman effect) and atomization techniques (wall and platform) for the direct determination of strontium in biological samples was carried out. Two instruments, one with deuterium and the other with Zeeman effect background corrections have been used to perform the experiments. Although La, Mg, Pd, Ta and Lu had a positive effect, lanthanum alone provided the best performance for the determination of strontium in whole blood, urine and bone digests using wall atomization without deuterium background correction. However, neither chemical modifier produced any significant improvement in sensitivity when Zeeman effect background correction with integrated platform atomization was used. Under the optimized conditions, the characteristic masses were 0.82 and 2.20 pg and the detection limits (3σ) were 0.13 and 0.30 μg l⁻¹ with wall atomization and with Zeeman effect background correction respectively. Recovery studies and analysis of standard reference materials certified for strontium were performed to assess the accuracy. The results for the determination of strontium in real samples with wall atomization and lanthanum as chemical modifier, agreed well with those obtained with Zeeman effect background corrector with a precision typically between 0.5 and 3%. Both procedures can be recommended, and the choice will depend on instrument availability.     

A study of the Arrhenius behavior of the co-precipitation of radium, barium and strontium sulfate

Co-precipitation of radium, barium and strontium is an important process in many contexts, such as uranium mining, oil extraction and in the safety assessment of a final repository for used nuclear fuel. Co-precipitation to a solid solution is possible since radium, barium and strontium act as chemical analogues. In this work the co-precipitation of radium, barium and strontium was studied and the kinetic behavior of the co-precipitation process was investigated. It was shown that radium, barium and strontium co-precipitate congruently and that the precipitation followed an Arrhenius behavior and the Arrhenius parameters for the systems was determined. When studying the differences of the Arrhenius constants by using a student t test (95 % confidence interval) it was observed that the only significant difference in the activation energy, E _a, is between radium and barium and between radium and strontium respectively, the pure strontium having the larger activation energy in comparison. This is most likely coupled to the metal ion size; since the hydration waters are more strongly bound, which leads to them having a slower exchange rate, which in turn effects the rate of co-precipitation to the metal these reactions will be slower.     

Thermochemical Study of Gaseous Salts of Oxygen-containing Acids: XI. Alkaline-Earth Metal Titanates

Gas-phase equilibria involving beryllium, calcium, strontium, and barium titanates were studied by high-temperature mass spectrometry. Standard enthalpies of formation and atomization were determined for BeTiO₃, CaTiO₃, SrTiO₃, and BaTiO₃ molecules.     

Thermochemical study of gaseous salts of oxygen-containing acids: XX. Phosphates of beryllium and beryllates of alkaline-earth metals

Gas-phase reactions involving beryllium phosphates and calcium, strontium, and barium beryllates were studied. The standard enthalpies of gaseous formation and atomization of BePO₃, BePO₂, CaBeO₂, SrBeO₂, and BaBeO₂ salts were determined.     

溶胶-凝胶法制备Ba_(0.6)Sr_(0.4)TiO_3陶瓷纤维

首次采用乙酰丙酮为钛醇盐的稳定剂,醋酸钡、醋酸锶和钛酸丁酯为原料,无水乙醇-冰醋酸作为溶剂,利用Sol-Gel法于1100℃得到单一钙钛矿相钛酸锶钡陶瓷纤维.用TG、XRD、SEM等手段对产物进行表征.     

Determination of barium and strontium peroxides (active oxygen) in igniters in small-arms tracer ammunition

A method is proposed for the determination of barium and strontium peroxides (active oxygen) in igniters in small-arms tracer ammunition. The sample is treated with dilute hydrochloric acid (1 + 9) which dissolves the magnesium powder almost instantaneously and then dissolves the barium or strontium peroxides within 10-30 min. The solution is then filtered to remove the organic substances (calcium resinate, "Parlon". Toluidine Red toner, and zinc stearate) and the peroxide is determined by means of the colour of the titanium-peroxide complex. It is shown that igniter mixes and igniters used in small-arms tracer ammunition deteriorate on storage.     

Formation and filtration characteristics of solids generated in a high level liquid waste treatment process

The solids formation behavior in a simulated high level liquid waste (HLLW) was experimentally examined, when the simulated HLLW was treated in the ordinary way of actual HLLW treatment process. Solids formation conditions and mechanism were closely discussed. The solids formation during a concentration step can be explained by considering the formation of zirconium phosphate, phosphomolybdic acid and precipitation of strontium and barium nitrates and their solubilities. For the solids formation during the denitration step, at least four courses were observed; formation of an undissolved material by a chemical reaction with each other of solute elements (zirconium, molybdenum, tellurium) precipitation by reduction (platinum group metals) formation of hydroxide or carbonate compounds (chromium, neodymium, iron nickel, strontium, barium) and a physical adsorption to stable solid such as zirconium molybdate (nickel, strontium, barium).     

Chemical modifiers in the determination of molybdenum in human serum by electrothermal atomic absorption spectrometry

Summary Various modifiers were investigated for the molybdenum determination in human serum samples by electrothermal atomization atomic absorption spectrometry. Methods with magnesium nitrate, barium difluoride, nitric acid, palladium-magnesium nitrate and palladium-hydroxylamine were studied by introducing the serum samples directly into the graphite furnace with 0.2% triton X-100. The mineralisation and atomization curves, the amount of modifier and the calibration and addition graphs were studied in all instances. The characteristic masses were 18, 22, 17, 12 and 13 pg of molybdenum for magnesium nitrate, barium difluoride, nitric acid, palladium-magnesium nitrate and palladium-hydroxylamine, respectively. The precision, accuracy and interferences of the methods were also investigated.     

Hydrothermally assisted complex polymerization method for barium strontium titanate powder synthesis

Barium strontium titanate was obtained by hydrothermal treatment of barium strontium titanate citric precursor solution, previously prepared by complex polymerization method. The thermally induced phase evolution was followed at various temperatures up to 800 °C using thermogravimetric and differential thermal analysis, X-ray diffraction analysis, and Raman spectroscopy. Microstructural characterization of barium strontium titanate powders was performed by scanning and transmission electron microscopy. The proposed synthesis route has been proven as a better and faster method for barium strontium titanate powder preparation as compared to the conventional complex polymerization route. The method was found efficient for production of low agglomerated, fine, nanosized barium strontium titanate powder with well defined stoichiometry, and sub-micron particle size. The results of structural and microstructural characterization showed the complete crystallization of carbonate-free barium strontium titanate powder at 700 °C with an average size of crystallites below 50 nm.     

Characterization and application of SuperLig<Superscript>®</Superscript> 620 solid phase extraction resin for automated process monitoring of <Superscript>90</Superscript>Sr

Characterization of SuperLig^® 620 solid phase extraction resin was performed in order to develop an automated on-line process monitor for ⁹⁰Sr. The main focus was on strontium separation from barium, with the goal of developing an automated separation process for ⁹⁰Sr in high-level wastes. High-level waste contains significant ¹³⁷Cs activity, of which ^137mBa is of great concern as an interference to the quantification of strontium. In addition barium, yttrium and plutonium were studied as potential interferences to strontium uptake and detection. A number of complexants were studied in a series of batch K_d experiments, as SuperLig^® 620 was not previously known to elute strontium in typical mineral acids. The optimal separation was found using a 2 M nitric acid load solution with a strontium elution step of ~0.49 M ammonium citrate and a barium elution step of ~1.8 M ammonium citrate. ⁹⁰Sr quantification of Hanford high-level tank waste was performed on a sequential injection analysis microfluidics system coupled to a flow-cell detector. The results of the on-line procedure are compared to standard radiochemical techniques in this paper.