电感耦合等离子体原子发射光谱(ICP-AES)法测定钢中硼时样品溶解损失及空白控制研究

用电感耦合等离子体原子发射光谱(ICP-AES)法研究了钢中硼的测定。实验发现,分析线在硼182.64nm处无硼铁基体空白值低于纯试剂(无铁)空白值。样品分析时,应进行无硼铁基空白实验,结果计算只能用此空白值。对普通玻璃烧杯和聚四氟乙烯烧杯的酸溶样品测定结果进行了比较,结果表明,测定结果和空白值相近且都很低,无硼普通玻璃烧杯也能满足钢中低含量硼的测定需要。通过对实验与报道结果比较分析表明,硝酸或王水加热溶解样品得到的溶液中硼没有损失,此溶液可测定钢中酸溶硼;用高氯酸发烟处理后,样品中酸不溶硼可能会溶解,但硼会挥发损失。因此,高氯酸发烟处理不能测定硼。     

负热电离质谱测定硼同位素的涂样试剂比较

目前人们并未注意到利用负热电离质谱方法测定硼同位素所采用涂样试剂中BO^-的同质异位素CNO^-离子的存在和影响。对硼同位素测定采用的不同涂样试剂进行比较，结果发现在去硼海水和硝酸盐溶液中存在BO2^-的同质异位素CNO^-离子，干扰离子不仅来自有机物，而且可能来自硝酸根。在硼同位素测定中，检查空白中的43峰和43／42比值是必要的。实验表明MgCl2 NaOH混合溶液是负热电离质谱测定硼同位素的较为理想的涂样试剂。     

Prompt gamma-ray neutron activation analysis methodology for determination of boron from trace to major contents

Prompt gamma ray neutron activation analysis methodologies were standardized using a reflected neutron beam and Compton suppressed γ-ray spectrometer to quantify boron from trace to major concentrations. Neutron self-shielding correction factors for higher boron contents (0.2–10 mg) in samples were obtained from the sensitivity of chlorine by irradiating KCl with and without boron. This method was validated by determining boron concentrations in six boron compounds and applied to three borosilicate glass samples with boron contents in the range of 1–10 mg. Low concentrations of boron (10–58 mg kg⁻¹) were also determined in two samples and five reference materials from NIST and IAEA.     

珊瑚中硼的分离及其同位素组成的测定

介绍了用硼特效树脂和阴、阳混合离子交换树脂相结合进行珊瑚中硼的分离和纯化方法，满足了正热电离质谱法测定硼同位素的要求，并且对几个珊瑚样品进行了硼的分离和硼同位素组成的测定，结果满意，为研究珊瑚中的硼同位素示踪古海洋环境变化提供了可能。     

Spectrophotometric determination of trace and ultratrace levels of boron in silicon and chlorosilane samples

Summary Spectrophotometric methods for the determination of boron in the low g/g and ng/g range in high-purity silicon and dichloro- and trichlorosilanes were investigated in detail. The procedures established involve dissolution of silicon samples and the hydrolyzed products of chlorosilane samples in hydrofluoric acid-containing reagents followed by evaporation of the silicon matrix as H₂SiF₆. The boron retained in the treated sample solution was then determined by a spectrophotometric method using carminic acid as a chromatic reagent. Special effort has been paid to the control of the analytical blank and reproducible determination of boron. The results indicate that addition of mannitol and proper control of the evaporation process are effective in preventing volatilization of boron during the evaporation of silicon matrix and can thus attain high recovery of boron and reproducible analysis. Through meticulous control of the analytical blank and experimental conditions, the limit of detection for boron determination with the established method can be as low as ng/g levels. Application of the methods to the determination of boron in various stages of purification of silicon and trichlorosilane as well as in borophosphosilicate film was conducted.     

Matrix effects in the analysis of biological matrices by axial view inductively coupled plasma optical emission spectrometry

We are reporting observations of positive and negative variations of emission line intensities during the determination of boron and titanium in biological matrices by axial view inductively coupled plasma optical emission spectrometry with segmented charge-coupled device detection. The study included the testing of several elements (yttrium, palladium and platinum) and analytical wavelengths for internal standardization, aiming to compensate for variations in signal recovery due to matrix interferences. Human albumin was chosen as principal matrix component to assess the effect of variable chemical and instrumental operating conditions on boron response. A parametric study was performed by considering the application of two different nebulizer–aerosol chamber systems, the effect of plasma operating conditions on analyte and internal standard signals and the influence of common blood plasma electrolytes, added as salts of alkaline or alkaline earth elements. The pneumatic injection systems tested were a standard cross-flow nebulizer with a Scott type spray chamber and a concentric Meinhard type device coupled to a glass cyclonic spray chamber. The change from standard (i.e. medium RF power and relatively high aerosol carrier gas flow rate) to robust (i.e. higher RF power and lower carrier gas flow rate) conditions contributed to large, non-correlated variations in boron intensities and in some of the analyte/internal standard ratios. Significant memory effects were observed for injection of boron solutions prepared with boric acid and containing small amounts of acid, but those effects were negligible when the boron carrier compound was boronophenylalanyne. The injection of titanium solutions did not produce analyte carry-over effects. When internal standards were employed, a less effective signal compensation was consistently observed for boron at higher albumin concentrations when the difference in energies of the lines was between 4.5 and 6 eV. This effect was enhanced for some line pairs when robust conditions are employed. Differences in the response between nebulizers were minor, with a slight advantage in sensitivity for the cross-flow/Scott system. Yttrium was found to be useful for signal compensation in the determination of boron and titanium in blood and human plasma provided that the equivalent concentration of albumin in the nebulized sample dilutions was kept below 0.2% w/v. Simultaneous measurement of a reference strontium line was found to be useful as an additional verification of the response of yttrium as internal standard.     

Precise determination of boron in titanium by inductively coupled plasma mass spectrometry

A method was developed for the determination of boron in titanium by inductively coupled plasma mass spectrometry (ICP-MS). A commercially available PTFE sample introduction system, leading to the desired low detection limits for boron, was used. The method is suitable for the determination of boron concentrations down to about 1 μg g^?1 in the solid material. The influence of the internal standard on the precision was studied and beryllium was selected as the internal standard. For the titanium analysed (BCR reference material 090), the ICP-MS result agreed with those obtained using other techniques. Several bars of titanium reference material were supplied and a study of the homogeneity of boron in this material was made. Using analysis of variance on the results obtained for the different bars, the homogeneity of boron in the reference material could be estimated to be better than 2.1%.     

提硼离子交换树脂研究进展

简单介绍了离子交换树脂法提取硼的原理,从葡甲胺、多元醇、糖类、邻-二元酚类不同功能基以及聚苯乙烯、聚丙烯酸酯、无机-有机复合型树脂及天然高分子等不同基质材料的角度综述了提硼离子交换树脂的研究现状,认为葡甲胺是目前使用效果最好的功能基化试剂,而基质材料则各有优缺点.同时对硼离子交换树脂在水处理、环境保护、提取分离等领域的应用进行了概括,并对新型提硼树脂的研究进行了展望.     

不同基因型油菜苗期地上部硼分布及运转能力的差异探讨

通过大田试验，对低硼胁迫下不同基因型油菜地上部的硼分布和转动能力作了初步研究。结果表明：油菜苗期地上部各器官硼的分布以叶片最高，叶是硼胁迫反应敏感的器官。耐低硼迫品种间有差异。相对耐低硼胁迫的品种具有较强的硼吸收和转运能力。     

Changes of the affinity between fungal proteins and vanillin bonded to thermally modified porous glass support

Summary The affinity of peroxidase and the fungal proteins to vanillin attached to controlled porous glasses depends on the porosity of the glass and additional thermal treatment of the support. The additional thermal treatment of controlled porous glasses leads to an enrichment in boron atoms of their surface.The results presented in this paper show a better resolution of the analyzed substances when glass with a surface enriched in boron was used as the support for vanillin.     

The Role of Chemistry in the Development of Boron Neutron Capture Therapy of Cancer

A therapeutic method that selectively destroys malignant cells in the presence of normal cells is a highly valued goal of oncologists and the possible salvation of cancer patients afflicted with some incurable forms of the disease. Selective cell destruction is, in principle, possible with a binary therapeutic strategy based upon the neutron capture reaction observed with the ¹⁰B nucleus and a neutron of low kinetic energy (thermal neutron). This nuclear fission reaction produces both ⁴He and ⁷Li⁺ nuclei along with about 2.4 MeV of kinetic energy and weak γ-radiation. Since the energetic and cytotoxic product ions travel only about one cell diameter in tissue one may specify the cell type to be destroyed by placing innocent ¹⁰B nuclei on or within only the doomed cells. This article describes the current status of chemical research aimed at the eventual adoption of this therapeutic method (boron neutron capture therapy or BNCT). The multidisciplinary nature of this research effort involves chemistry, biology, nuclear physics, medicine, and related specialties. Methods devised for bringing ¹⁰B nuclei to tumor cells in therapeutic amounts are correlated with the structure of a generalized cell and the various cellular compartments available for boron localization. The synthesis methods employed for the creation of boron-containing biomolecules and drugs are presented along with representative data concerning their efficacy in tumor localization. The outlook for BNCT is especially bright at this time because of rapid developments in the fields of bioorganometallic chemistry, microbiology, immunology, and nuclear science, to name but a few. Very effective boron delivery vehicles have been demonstrated, and through the interaction of chemistry and biology these species are undergoing further improvement and evaluation of their suitability for BNCT.     

Concerted effect of boron and porosity on shear thickening behavior of hybrid mesoporous silica dispersions

In the present work, the influence of porosity and boron on shear thickening behavior of hybrid mesoporous silica has been studied. Three different levels of boron modification were performed by varying the molar composition of boric acid viz., 1.5 mmol, 2.5 mmol, and 3.5 mmol in a co-condensation approach. The incorporation of boron in mesoporous silica network was confirmed by various techniques such as Fourier transform infra-red (FTIR), and ¹¹B solid- state nuclear magnetic resonance (NMR) spectroscopy. The morphology and particle size were confirmed by using scanning and transmission electron microscopy. To evaluate the effect of boron and porosity on the shear thickening behavior, dispersions were prepared from mesoporous boron- modified silica (MSiB), control mesoporous silica (MSi), non-porous boron-modified silica (SiB), and control non-porous silica (Si) in polyethylene glycol. The shear thickening behavior was studied using steady shear rheology. The dispersion prepared from different loadings of synthesized MSiB containing 1.5 mmol boron showed more than 16 times increase in viscosity (657.7 Pa.s) compared to that of MSi (39.2 Pa.s) at a fairly low volume fraction (φ = 0.15) of silica. It is expected that the highly ordered mesoporous architecture of hybrid silica has improved the interaction between the particle and the dispersing medium through hydrogen bonding. The porous morphology of the hybrid mesoporous silica as well as the incorporation of boron in the silica network favors the formation of a frictional contact network, and a transition from continuous shear thickening (CST) to discontinuous shear thickening (DST) behavior was observed. Therefore, silica prepared via incorporation of boron as well as porosity can be material of interest in variety of applications, for example, soft body armors, sporting goods, and shear thickening electrolytes for high impact resistant batteries.     

On-line generation and hydrolysis of methyl borate for the spectrophotometric determination of boron in soil and plants with azomethine-H

A continuous-flow system for boron determination in soils and plants with spectrophotometric detection using the azometihine-H-boron complex method was developed. In order to avoid the interferences of concomitants present in samples and to increase the sensitivity, the element was separated on-line from the matrix by methyl borate generation. For this purpose, a concentrated sulfuric acid sample solution was combined with methanol in 1:3 ratio which produce enough heating for the esterification reaction without external source. Subsequently, the methyl borate produced was stripped by the addition of a nitrogen flow and separated from the bulk solution in a gas-liquid separator to be then hydrolyzed in an ammonium-phosphate buffer solution (pH 6.8). Finally, the new bulk of phases were separated in a second gas-liquid separator and the liquid phase was combined with azomethine-H to form a boron complex for its detection at 420 nm. The effects of a number of possible interferents, both anionic and cationic were evaluated. The most severe depressions were caused by fluoride and potassium for which a concentration of 100 μg ml⁻¹ caused a 5% depression on the signal. A linear response was obtained between the detection limit of 0.05 μg ml⁻¹ (3σ of the blank) and 50 μg ml⁻¹ of boron. The precision (R.S.D.%) for 10 consecutive readings of the same solution (5.0 μg ml⁻¹ of boron) was 2.6%. Recoveries of boron added to the samples before the extraction process were 94, 97, and 101% for soil, fruit tissue, and leaf tissue, respectively. The developed system was applied to the determination of boron in soil, fruits tissue, and leaves tissue of coffee plantations from different towns of Mérida State, Venezuela.     

The morphology of ceramic phases in BxC-SiC-Si infiltrated composites

The present communication is concerned with the effect of the carbon source on the morphology of reaction bonded boron carbide (B₄C). Molten silicon reacts strongly and rapidly with free carbon to form large, faceted, regular polygon-shaped SiC particles, usually embedded in residual silicon pools. In the absence of free carbon, the formation of SiC relies on carbon that originates from within the boron carbide particles. Examination of the reaction bonded boron carbide revealed a core-rim microstructure consisting of boron carbide particles surrounded by secondary boron carbide containing some dissolved silicon. This microstructure is generated as the outcome of a dissolution-precipitation process. In the course of the infiltration process molten Si dissolves some boron carbide until its saturation with B and C. Subsequently, precipitation of secondary boron carbide enriched with boron and silicon takes place. In parallel, elongated, strongly twinned, faceted SiC particles are generated by rapid growth along preferred crystallographic directions. This sequence of events is supported by X-ray diffraction and microcompositional analysis and well accounted for by the thermodynamic analysis of the ternary B-C-Si system.     

How boron incorporation during Si1−xGex chemical vapor deposition degrades the Ge profile

The effect of boron incorporation during chemical vapor deposition of SiGe thin films from silane, germane, diborane, and hydrogen gas mixtures is investigated. It is shown that boron incorporation during SiGe thin-film growth degrades the Ge profile under certain growth conditions when the boron concentration is high enough (>10¹⁹ cm⁻³). In single-wafer atmospheric-pressure processes we find that no Ge concentration depression occurs at deposition temperatures above 675 °C. In multi-wafer atmospheric-pressure processes we find an increasingly occurring depression of the Ge concentration along the wafer stack, even at temperatures above 675 °C. In low-pressure processes, high-level in-situ doping of SiGe with boron is possible at temperatures as low as 550 °C without any degradation of the Ge profile. Thus LPCVD is superior to APCVD with respect to high-level in situ doping of SiGe with boron. The presence or absence of Ge profile degradation in boron-doped SiGe thin films is explained by the discussion of growth rate enhancement phenomena. Received: 15 September 1997 / Accepted: 7 November 1997     

Comparison of different types of filters for atmospheric trace element analysis by three analytical methods

Different atmospheric aerosol samples were collected on three types of filters. From both of the loaded and clean areas of each kind of filter, different disks were cut and investigated by XRF, PIXE and scanning electron microscopy (SEM). The blank concentration values of the elements Al, Si, P, S, Cl, K, Ca, Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, As, Br and Pb in the three types of filter are discussed. It is found that for trace elemental analysis, the Nuclepore membrane filters are the most suitable for sampling. These filters have much lower blank element concentrations than the glass fiber and ash free filters. It was found also that PIXE is a more reliable analytical technique for atmospheric aerosol particles than the other methods used.     

Isomorphous substitution of silicon by boron in layered sodium silicate hydrates

To investigate the influence of boron on the crystallization process and the substitution of silicon by boron in silicate layers, layered sodium silicate hydrates (Na-SH) have been synthesized hydrothermally from a boron-containing mixture. XRD measurements confirm the high crystallinity of the synthesized Na-SH.¹¹B MAS NMR measurements indicate that boron is incorporated luto the silicate layers instead of silicon atoms.     

Spectrophotometric determination of iron and boron in soil extracts using a multi-syringe flow injection system

In the last decade, significant advances in flow analysis have been reported, namely the extensive use of computer-controlled devices to enhance the autonomy and performance of analysers. In the present work, computer-controlled multi-syringe flow injection systems are proposed to perform the spectrophotometric determination of available iron and boron in soil extracts. The methodologies were based on the formation of ferroin complex (determination of iron) and azomethine-H reaction (determination of boron). Both determinations were performed in manifolds with similar configurations by changing the reagents present in the different syringes. In the determination of iron, elimination of Schlieren effect in the detection system was achieved through the binary sampling approach, where a three-way valve was actuated to intercalate small slugs of sample and reagent, promoting better mixing conditions for solutions with different values of refractive index. In the determination of boron, in-line sample blank measurement was attained by omitting the introduction of reagent through software control, without manifold reconfiguration. Linear calibration curves were established between 0.50 and 10.0 mg Fe l⁻¹ and between 0.20 and 4.0 mg B l⁻¹. No systematic difference was found when soil extracts were analysed by the proposed methodologies and compared to the respective reference procedures.     

Characterization of the distribution of the sintering activator boron in powder metallurgical steels with SIMS

Powder metallurgy is a well-established method for manufacturing ferrous precision parts. A very important step is sintering, which can be strongly enhanced by the formation of a liquid phase during the sintering process. Boron activates this process by forming such a liquid phase at about 1200 °C. In this work, the sintering of Fe–B was performed under the protective atmospheres of hydrogen, argon or nitrogen. Using different grain sizes of the added ferroboron leads to different formations of pores and to the formation of secondary pores. The effect of boron was investigated by means of Secondary Ion Mass Spectrometry (SIMS) supported by Scanning Electron Microscopy (SEM) and Light Microscopy (LM). To verify the influence of the process parameters on the mechanical properties, the microstructure (pore shape) was examined and impact energy measurements were performed.The concentrations of B in different samples were varied from 0.03–0.6 weight percent (wt%). Higher boron concentrations are detectable by EPMA, whereas the distributions of boron in the samples with interesting overall concentration in the low wt% range are only detectable by means of SIMS.This work shows that the distribution of boron strongly depends on its concentration and the sintering atmosphere used. At low concentration (up to 0.1 wt%) there are boride precipitations; at higher concentration there is a eutectic iron–boron grain boundary network. There is a decrease of the impact energy observed that correlates with the amount of eutectic phase.     

Some physical properties of compacted specimens of highly dispersed boron carbide and boron suboxide

Structure, shear modulus and internal friction (IF) of compacted specimens of boron carbide and boron suboxide have been investigated. Microtwins and stacking faults were observed along the {100} plane systems of polycrystalline specimens of boron carbide. Electrical conductivity of the specimens was that of p-type. Concentration of holes varied from 10¹⁷ to 10¹⁹ cm⁻³. The IF was measured in the temperature range 80-300 K. It was shown that the IF of boron carbide and that of boron suboxide were characterized with a set of similar relaxation processes. Mechanisms of the relaxation processes in boron carbide and boron suboxide are discussed in terms of the Hasiguti model of interaction between dislocations and point defects.