Ion Exchange Extraction of Boron from Aqueous Fluids by Amberlite IRA 743 Resin

The ion exchange characteristics d Amherlite IRA 743 resin for extracting boron from aqueous fluids have been investigated in detail. The results show that AmherHte IRA 743 resin, a boron specific ion exchange resin, can quantitatively extract boron as the B (OH)4- spedes from weakly basle solution. Some exchangeable anions such as CI- and SO4^2- are present, resulting in an increase in pH value of the loeded solution within the nan, and the boron in natural aqueous fluids with low nH is also extracted by Amberlite IRA 743 resin. However, the voiume of loaded solution must be restricted. The maximum voiume of loaded solution giving quantitative extraction of boron decreases for sample soh.,tiom of lower pH value. Warm HCI solution is more effective than room temperature HCI solution for eluting boron from Amberllte IRA 743 resin.     

盐湖卤水硼同位素测定中硼的二次离子交换分离

根据盐湖卤水水化学特点,介绍了一种用阳、阴离子交换树脂,动态和静态交换相结合,对盐湖卤水中的硼进行分离纯化的简易方法。用该方法从盐湖卤水中分离出来的硼足以满足同位素质谱分析的需要,分离过程不产生同位素分馏,获得了理想的实验结果。     

Polyether—phosphinite for One—phase Catalysis Coupled with Two—phase Separation

Polyether moiety was introduced to the phosphinite and the phosphinite modified rhodium complex formed in situ was highly active in the hydroformylation of higher olefins in organic monophase system. After reaction, on cooling to room temperature,the catalyst could precipitate out from organic phase and was easily separated by decantation and reused six times without obvious decreasing in activity.     

Energy-Resolved Ion Mobility-Mass Spectrometry—A Concept to Improve the Separation of Isomeric Carbohydrates

Recent works using ion mobility-mass spectrometry (IM-MS) have highlighted the power of this instrumental configuration to tackle one of the greatest challenges in glycomics and glycoproteomics: the existence of isobaric isomers. For a successful separation of species with identical mass but different structure via IM-MS, it is crucial to have sufficient IM resolution. In commercially available IM-MS instruments, however, this resolution is limited by the design of the instrument and usually cannot be increased at-will without extensive modifications. Here, we present a systematic approach to improve the resolving capability of IM-MS instruments using so-called energy-resolved ion mobility-mass spectrometry. The technique utilizes the fact that individual components in an isobaric mixture fragment at considerably different energies when activated in the gas phase via collision-induced dissociation (CID). As a result, certain components can be suppressed selectively at increased CID activation energy. Using a mixture of four isobaric carbohydrates, we show that each of the individual sugars can be resolved and unambiguously identified even when their drift times differ by as little as 3 %. However, the presented results also indicate that a certain difference in the gas-phase stability of the individual components is crucial for a successful separation via energy-resolved IM-MS.

Actional Mechanism of Trifluoroacetic Acid for the Separation of Biopolymers by Reversed-phase Liquid Chromatography

The present paper covers the actional mechanism of trifluoroacetic acid for the separation of biopolymers investigated by using the parameters of stoichiometric displacement model for retention(SDM-R) in reversed-phase liquid chromatography. It was found that the trifluoroacetic acid(TFA) may participate in, or stimulate the association among displacing agent molecules in mobile phase, and decrease the affinity of both the associate molecules of the displacing agent and the TFA-protein ion-pairing. The former dominates over the separation selectivity of biopolymers as the concentration of TFA is lower than a given value, and the two contrary functions partly offset to each other and the latter dominates as its concentration is greater than the given value.     

Surface Confined Ionic Liquid—A New Stationary Phase for the Separation of Ephedrines in High-performance Liquid Chromatography

In this article, a new and effective stationary phase based on ionic liquid modified silica is first reported and used for the separation of ephedrines in high-performance liquid chromatography (HPLC). The separation results indicate the high efficiency and reproducibility of the stationary phase. The electrostatic interaction, ion-exchange interaction between the solutes and the stationary phase are considered to attribute the effective separation. Moreover, the free silanols on the surface of the silica are effectively masked by the immobilized ionic liquid, a result of which is to decrease the non-specific absorption.     

Evaluation of Accuracy for the Measurement of Octanol–Water Partition Coefficient by MEEKC

Microemulsion electrokinetic chromatography (MEEKC) has been widely used as an indirect tool to measure octanol–water partition coefficients (logP _ow) of various kinds of compounds. In this paper, we present for the first time a mathematical model of the precision of logP _ow (ΔlogP _ow) as a function of the deviation of migration time (Δt _m) in MEEKC, and more importantly evaluated the accuracy of the MEEKC. Our model shows that for a given microemulsion system, there is an interval of migration times, where a high precision in the determination of logP _ow can be obtained. However, when the migration time approaches either the migration time of the electroosmotic flow or that of the microemulsion phase, the precision of logP _ow deteriorates rapidly. The model was experimentally verified by the microemulsion system with migration times of 6.50 and 32.00?min for the electroosmotic flow and microemulsion phase, respectively, and we found the useful logP _ow interval to be 0.50–5.50. The paper also demonstrates that the calibration constants between migration times t _m and predicted logP _ow values could be transferred with high accuracy from one MEEKC system to another as long as both systems are set up to use the same operational parameters.     

Simultaneous Separation and Determination of Four Bioactive Constituents in Traditional Chinese Medicinal Tablet Xinkeshu by HPLC-DAD

Introduction In recent years there has been a renaissance of inter-est in use of traditional Chinese medicinal preparation (TCMP) because of the realization that traditional Chi-nese medicine can act in a synergistic manner in the human body, and can provide unique therapeutic prop-erties with minimal or no undesirable side-effects.1 The modernization research on TCMP is in process in China, and the first step is to establish simple and reliable ana-lytical technologies and methodologies f…     

A General Two—Step Procedure for the N—Alkylation of Selenoamides

Selenoamides are prepared via N-alkylated in a two-step proce-dure:Benzotriazole,aldehyde and primary selenoamide reacted togeher to yield an adduct which was then reduced to the N-substituted selenoamide by NaBH4.     

Sensitivity—enhanced Experiments for the Measurement of J and Dipolar Coupling Constants

A sensitivity-enhanced IPAP NMR experiment was described in this paper,which separates the ^1H-^15N doublets into two different spectra to alleviate the problem of resonance overlaps and achieve the accurate measurement of J and residual dipolar coupling constants in proteins.This experiment offered 20%-60% sensitivity enhancement over the original IPAP experiment,and therefore produced more measurable resonances.Pulsed field gradient was used for coherence selection.Water-flip-back approach was used for water suppression.The sensitivity-enhanced IPAP experiment was employed in the measurement of ^1JNH and ^1DNH constants of the protein UBC9.     

有孔虫中硼的分离及其正热电离质谱法测定

针对大洋钻探计划(0DP)钻孔中有孔虫数量少、硼含量低的特点，改进了硼特效树脂和阴、阳混合离子交换树脂相结合进行分离硼的方法，成功地实现了硼的分离，并且首次采用正热电离质语法测定了有孔虫中硼同位素的比值。由于硼的分离过程不产生同位素分馏，测定结果令人满意。     

Cd同位素地质样品的预处理方法研究

考察了文献报道的地质样品中Cd同位素测试前的化学分离纯化和富集方法(预处理方法)中的离子交换树脂单柱法回收率低的原因,并在该方法的基础上做了改进,优化了离子交换柱的洗涤顺序和洗液用量.改进后的离子交换树脂单柱法Cd回收率达99.82%,主要干扰元素(Sn、In、Zn、Pb)和基质元素的去除效果均较理想,能更好地满足Cd同位素的测定要求.     

Sample Preparation for Emission Spectrographic Determination of Impurities in Elemental Boron

Abstract

Accurate spectrographic determination of impurities in high-purity elemental boron requires that impurity elements be concentrated and collected in a suitable matrix while boron is separated from the sample. A method of acid dissolution followed by boron volatilization through an acetic anhydride and methanol treatment has been developed. This procedure is considerably faster and leaves lower residual boron concentrations than other methods. The mild conditions used to volatilize boron avoid the loss of any impurity elements from the sample.     

Wrapping an Organic Reducing Reagent in a Cationic Boron Complex and Its Use in the Synthesis of Polyhalide Monoanionic Networks

The reaction between BF₃ ? OEt₂ and one of two guanidines, 1,8‐bis(tetramethylguanidinyl)naphthalene (btmgn) and 1,2,4,5‐tetrakis(tetramethylguanidinyl)naphthalene (ttmgn), yields the salts [(btmgn)(BF₂)]BF₄ and [(ttmgn)(BF₂)₂](BF₄)₂. NMR spectroscopic data show that the boron atoms in the cation and anion exchange in the case of [(ttmgn)(BF₂)₂](BF₄)₂, but not in the case of [(btmgn)(BF₂)]BF₄. The rate constant for this exchange was estimated to be 4 s^?1 at 80 °C for solutions in CH₃CN. These salts were subsequently used for the reduction of dihalides Br₂ or I₂ to give polyhalide salts. We report the synthesis and first complete characterization (including structural analysis) of salts that contain pentabromide monoanions. In these salts, the Br₅^? anions interact to give dimeric units or polymeric chains. Our results are compared to previous quantum chemical calculations on the gas‐phase structure of the Br₅^? anion. The possible pathways that lead to the polyhalides are evaluated. In the case of [(ttmgn)(BF₂)₂](BF₄)₂, reduction is accompanied by ttmgn oxidation, whereas in the case of [(btmgn)(BF₂)]BF₄ reduction is initiated by aromatic substitution.     

柱色谱分离蔗糖酰化产物中蔗糖-6-乙酸酯的研究

通过蔗糖C-6位羟基的选择性乙酰化反应,合成的蔗糖-6-乙酸酯是进一步制备卤代蔗糖衍生物的重要中间体[1]。三氯蔗糖是目前被广泛关注的一种新型卤代蔗糖衍生物[2],它是以天然的蔗糖为原料,经半化学合成而得到的强力甜味剂,具有高甜度、低热值、无毒和抗龋齿等特点。在众多的三氯蔗糖的合成方法中[3-5],必须首先要对活泼的蔗糖C-6位羟基进行保护,即蔗糖的选择性酰化反应。蔗糖的乙酰化产物中除蔗糖-6-乙酸酯外,还有未转化的原料蔗糖和部分反应副产物。因此,为了减轻后续工艺合成的难度,降低制备成本,使最终产物三氯蔗糖容易提纯,必须对酰化…     

阴离子交换树脂分离富集/电感耦合等离子体质谱测定珊瑚中铅的同位素组成

在自制微型离子交换柱的基础上,建立了阴离子交换树脂AG1-X8分离富集珊瑚中痕量元素Pb的前处理方法,并使用高分辨电感耦合等离子体质谱(HR-ICP-MS)测定了海南橙黄滨珊瑚(porites lutea)样品中的Pb同位素比值。从全程空白值、洗脱曲线、回收率和基体分离情况等方面考察了不同洗脱剂的洗脱效果,结果表明,采用0.50 mol/L HNO3时的洗脱效果最好,方法的全程空白值为18 pg,Pb的回收率为99.6%,在洗脱过程中无拖尾现象,且能与Ca、Sr、Mg、Fe、Mn、Zn、Ba和U等珊瑚中的基体元素成功分离,对上述基体元素的去除率均能达到99.8%以上。使用该方法测得海南珊瑚样品中的207Pb/206Pb、208Pb/206Pb比值分别为0.850 5、2.087 0,相对标准偏差(RSDs,n=21)分别为0.12%和0.11%。该法质量控制良好,表明建立的AG1-X8阴离子交换树脂分离富集/HR-ICP-MS测定珊瑚中Pb的同位素组成的方法可靠,可推广应用于其它复杂样品中铅同位素组成的测定。     

天然样品中锂的分离及其同位素比值的测定

以锂元素标准样品和K、Na、Ca、Mg元素标准样品的混合溶液为主要研究对象,采用阳离子交换树脂AG-50W X8(0.032~0.098 mm粒径)来分离富集L i,探索不同淋洗介质(包括盐酸、硝酸以及与甲醇、乙醇的混合)对L i分离纯化的最佳效果。在对比研究的基础上,建立了一种有效分离提纯天然样品中L i的方法。用本方法分离了水体、土壤、岩石等天然样品中的L i,并用MC-ICP-MS准确测定了L i同位素组成。研究结果表明,该方法的精度在0.1‰~1.0‰,与目前文献报道的分析方法具有相似的精度。经过流程前后单元素标准L i同位素比值(7δL i)的比较,发现化学处理过程所产生的同位素分馏约为0.3‰,化学处理的流程空白可以忽略不计。该方法测定海水7δL i值为(31.6±1.0)‰,与前人的分析结果吻合。因此,本方法可用于测定天然样品中的L i同位素组成。     

Speciation Analysis of Inorganic Tin (Sn(II)/Sn(IV)) by Graphite Furnace Atomic Absorption Spectrometry Following Ion-Exchange Separation

A new method based on anion exchange resin separation and graphite furnace atomic absorption spectrometry (GFAAS) detection is proposed for the determination of inorganic tin species. The result showed that Sn(IV) was quantitatively retained on the resin when [HCl] = 9.0 mol · L⁻¹, but Sn(II) could not be adsorbed on the resin under the same condition. Thus, a separation of Sn(II) and Sn(IV) has been realized. When the concentration of NaOH solution was between 2.0–7.0 mol · L⁻¹, Sn(IV) that adsorbed on the resin could be eluated from the resin completely. Meanwhile, under the atmosphere and the nitrogen states, the translation between Sn(II) and Sn(IV) was investigated. Under the optimal conditions, the detection limit of Sn(IV) is 0.40 μg · L⁻¹ with RSD of 2.3% (n = 5, c = 2.0 μg · L⁻¹). The proposed method was applied to the speciation analysis of tin in different water samples and the recovery of total Sn was in the range of 98.7–101.7%. In order to verify the accuracy of the method, a certified reference water sample was analyzed and the results obtained were in good agreement with the certified value.