ICP—AES中基体及操作条件对元素电离度的影响

本文测定了Ca、Cd、Mg、Mn、Zn5种元素电离度在1CP中的垂直空间分布,观察了基体元素及操作条件(正向功率与载气流量)对电离度的影响,结果表明,元素的电离度与ICP的激发特性没有直接的联系;基体元素及操作条件对电离度影响很小。     

Microwave Effects Due to Anionic or Cationic Initiators in Emulsion Polymerization Reactions

Summary: Emulsion polymerization reactions were performed under microwave irradiation and conventional heating using anionic or cationic initiators and surfactants. Microwave irradiation promoted higher reaction rates for both initiators and surfactants, in comparison with the conventional heating. The effect of high power microwave irradiation was studied using a method of cycles of heating and cooling, where rapid polymerization reactions were obtained. In the reactions with anionic initiator and surfactant, a decrease in the particle diameters was observed with microwave heating, and even smaller particles were obtained using high power microwave irradiation. Moreover, the decrease in the particle size was acompanied by an increase in the polymer molecular weight. On the other hand, these effects were not observed for reactions with cationic initiator and surfactant.     

Studies on System Peaks in Ion-Pair Adsorption Chromatography. II. Effects on Analyte Peak Compression and Deformation

Abstract

Peak compression and deformation effects were studied in a reversed phase ion-pair adsorption chromatographic system, comprising silanized (C₁₈) silica as solid phase and an acidic mobile phase. An indirect detection technique was used, protriptyline (a secondary hydrophobic amine) being the probe, and substituted benzamides the analytes.     

Study of the Linear Range in HPLC Analyses with UV Detection: Methodology and Experimental Application to the Influence of the Analyte UV Spectrum

Determination of the linear range is one of the main concerns in validation of an HPLC analysis method. It is particularly important since single point calibration will be then used routinely. We proposed an iterative methodology to handle this problem. The idea was, at each step, to test statistically whether the following point belonged to the same regression line. The methodology was then used to evaluate quantitatively the effect on linear range of a shift in detection wavelength or of the detector bandwidth. Although experimental results were globally in accordance with spectroscopic theory, magnitudes observed were rather large. So the linear range could vary by a factor of over 2 with changes in conditions that remained within the range of current practical values. Changes in detection wavelength were limited to about fifteen nm around λ_max and the detector used was considered to be representative of modern high-performance UV detectors. The question of how to take consequences in method validation into account was raised. The solution proposed recommended that the validation was undertaken in conditions as close as possible to those where the method would be conducted routinely. This means with the same instrumentation and on the product of interest for analyses.     

浅谈中药中微量元素的系统研究

提出了中医药微量元素系统研究的新思考．主要是在中医药理论的指导下一对中层中药的微量元素进行全面系统研究．在进行系统研究时,要做到以多元素、多因素分析为主．必须加强对样品前处理的研究及进行测定的质量控制等．     

煤烟对食物、饮水氟污染的研究

测定了云南滇东“燃煤污染型”氟病区新、陈玉米(皮、饭)、饮用水(自然井水、泉水、室内缸水、开水)的含氟量，并对玉米、豆娄、辣椒进行水洗脱氟试验，结果证明由于用煤方式不当，造成室内食物、饮水的污染，发生氟中毒。     

Application of A Multichannel Potentiostat to Metal Ion Determinations in Flow Injection Analysis

Abstract

A 4-channel potentiostat has been developed for use with an amperometric array and applied to the determination of a mixture of metal ions in flow injection analysis (FIA). The use of an array facilitates the acquisition of three dimensional electrochemical information in real-time (current vs. potential vs. time). The data acquired can be saved in ASCII format which facilitates post-run plotting of the 2-and 3-D voltammograms in Microsoft Excel. The results demonstrate the increased information content available with an amperometric array over fixed potential electrodes. The ability to identify the individual species in mixed component injections, which is normally not possible with FIA without a prior separation step has been demonstrated. Linear responses to injections of copper(II) ions in the concentration range 500 ppm to 100 ppb were obtained.     

Cooperative Study of Precision and Accuracy on the Determinations of Around-Ppb Levels of Copper and Lead in Environmental Waters

The results of a series of inter-laboratory cross-check on the determinations of ppb and sub-ppb levels of copper and lead in environmental samples are described. Thirteen laboratories participated during a five-stage comparison. Seven analytical methods and two pre-concentration procedures were performed on certified and real samples. For controlled and blind standards at higher concentration levels (10 ppb or above) the data reported by different participants show good agreement for both elements regardless of the method chosen. However, for samples having lower concentrations (1-10 ppb level), the relative standard deviation (R.S.D.) and bias increased. A high degree of scattering on data were demonstrated for a deep ocean water at less than 1 ppb level. The results of the present study give direct comparison between different analytical methods, and also reflect the average aptitude of analytical laboratories in Taiwan on the measurements of copper and lead in environmental samples.     

Determinations of boron and chloride in highly radioactive sample solution

To meet the requirements of NUREG-0737 and Atomic Energy Council, Republic of China, the post accident sampling systems have recently been established at Taiwan power stations. The lead shielded cask for transportation of grab liquid sample from sampling station to the off-site backup laboratory was designed, based on the functions of sample taken vertically from sample station and the horizontal transferring of sample vial to the cell of backup laboratory. Spectrophotometric, titrimetric and ion chromatographic methods were studied and comparisons made for the analyses of boron and chloride. It can be concluded that suppressed ion chromatography with remote handling in a lead cell is best for determining boron and chloride simultaneously in a high radioactive sample solution. The method with high accuracy, less interference and rapid analysis is considered and discussed.     

酶免疫测定中待测物体积占体系百分比与抑制中浓度的关系

1 引言 抑制中浓度(IC50)是指小分子物质酶免疫测定中抑制率为50%时的待测物浓度.现今文献中IC50值多以浓度表示.     

A Systematic Study on the Effects of Solvating Solvents and Additives in Localized High-Concentration Electrolytes over Electrochemical Performance of Lithium-Ion Batteries

Localized high-concentration electrolytes (LHCEs) based on five different types of solvents were systematically studied and compared in lithium (Li)-ion batteries (LIBs). The unique solvation structure of LHCEs promotes the participation of Li salt in forming solid electrolyte interphase (SEI) on graphite (Gr) anode, which enables solvents previously considered incompatible with Gr to achieve reversible lithiation/delithiation. However, the long cyclability of LIBs is still subject to the intrinsic properties of the solvent species in LHCEs. Such issue can be readily resolved by introducing a small amount of additive into LHCEs. The synergetic decompositions of Li salt, solvating solvent and additive yield effective SEIs and cathode electrolyte interphases (CEIs) in most of the studied LHCEs. This study reveals that both the structure and the composition of solvation sheaths in LHCEs have significant effect on SEI and CEI, and consequently, the cycle life of energetically dense LIBs.     

化学学业不良学生的典型表现与原因分析

化学学业不良学生的典型表现与原因分析陈彦芬（河北衡水师范专科学校０５３０００）学业不良是教育现实中复杂而多方面的现象,需要作出多视角的研究。其中首要的一点就是应当追寻其产生的原因。我们在普通高中一年级的化学教学中对这一问题作了一些初步的探讨,在个案研...     

Radioimmltnoassay Determinations of p-Hydroxiphenformin and of Apparent Phenformin in Human Plasma or Serum

Abstract

Sensitive radioimmunoassay procedures are described for measuring p-hydroxyphenformin and apparent phenformin in human plasma or serum. The p-hydroxyphenformin procedure, which requires advance phenformin analysis, offers excellent accuracy. The determinations of apparent phenformin are influenced by the phenformin and p-hydroxyphenformin contents of the samples. Over a period of four months, the methods showed a precision associated with relative standard deviations of 12% for apparent phenformin and 13% for p-hydroxyphenformin.     

Manipulation of the Electroosmotic Flow in Glass und PMMA Microchips with Respect to Specific Enzymatic Glucose Determinations

The determination of glucose in microfluidic chips made of glass or PMMA was used as a model for the combination of an enzymatic reaction with the separation of compounds. It was based on the enzymatic oxidation of glucose and the amperometric detection of hydrogen peroxide. Real samples frequently contain compounds, such as ascorbic acid, which may interfere with quantitative glucose determinations. Thus, electrophoretic separation of specific from unspecific signals was envisaged by applying electric fields which are also used to control the flow of liquid via electroosmotic effects. Surface charge densities of the capillaries influence the electroosmotic flow (EOF). They are dependent on the chip material and on the adsorption of components from the background electrolyte. Reversal of the EOF after addition of cetyltrimethylammonium bromide (CTAB) and an increase in EOF after addition of sodium dodecylsulfate (SDS) were observed at lower surfactant concentrations with the PMMA chips rather than with the glass chips. For both chip materials these concentrations were below the critical micelle concentration. Effective separation of H₂O₂ and ascorbic acid was achieved with low CTAB concentrations, which lead to a reduction, but not to a reversal of the EOF. Reversal of the EOF by higher CTAB concentrations or the increase in cathodic EOF by SDS accelerated ascorbic acid transportation and reduced the differences in migration times. Thus, for the specific determination of glucose, glucose oxidase was added together with low CTAB concentrations to the background electrolyte. This avoided interference from ascorbic acid, and data obtained from the analysis of fruit juices showed a good correlation to data obtained from a reference method.     

Fragmentation and Isomerization Due to Field Heating in Traveling Wave Ion Mobility Spectrometry

During their travel inside a traveling wave ion mobility cell (TW IMS), ions are susceptible to heating because of the presence of high intensity electric fields. Here, we report effective temperatures T _eff,vib obtained at the injection and inside the mobility cell of a SYNAPT G2 HDMS spectrometer for different probe ions: benzylpyridinium ions and leucine enkephalin. Using standard parameter sets, we obtained a temperature of ~800 K at injection and 728?±?2 K into the IMS cell for p-methoxybenzylpyridinium. We found that T _eff,vib inside the cell was dependent on the separation parameters and on the nature of the analyte. While the mean energy of the Boltzmann distributions increases with ion size, the corresponding temperature decreases because of increasing numbers of vibrational normal modes. We also investigated conformational rearrangements of 7+ ions of cytochrome c and reveal isomerization of the most compact structure, therefore highlighting the effects of weak heating on the gas-phase structure of biologically relevant ions.

Determinations of traces of calcium in phosphoric acid and its salts by atomic-absorption spectrometry

A method for the determination of traces of calcium by atomic-absorption spectrometry after extraction into an organic solvent, has been investigated for the determination of traces of calcium in phosphoric acid and its salts. Calcium is extracted as the hydroxy-quinolate complex, the extract is introduced into the flame, and the calcium atomic-absorption is measured. The effects of pH, concentration of reagent, and diverse ions on the calcium extraction were investigated.     

Restriction of Spin Probe Motions in Polymer Composites Due to Chemical Factors

Abstract

Hyperfine splitting constants of the nitroxyl radical, with and without hydrogen bonds to the surrounding molecules, have been calculated using the UHF method on a 6-31G* base. In polyethylene filled with silica, hydrogen bonds are formed between nitroxyl radicals and —OH groups of the filler. The formation of hydrogen bonds leads to a change in the A _zz value from 3.33 mT for an isolated nitroxyl radical to 3.83 mT for a radical with a hydrogen bond. The relevant values as measured experimentally are 3.4 and 4.0 mT, respectively. The same procedure was used to calculate the theoretical A _zz value for a nitroxyl radical interacting with polyamide via a hydrogen bond. The value was found to be 3.63 mT (experimental value = 3.6 mT). Hydrogen bond formation results in a restricted motion of the nitroxyl radical in a polymeric medium.     

采用电位滴定法在DMSO/H2O混合溶剂体系中测定磺酰脲(胺)类除草剂的酸离解常数

采用电位滴定法在DMSO/H₂O(质量比80:20)混合体系中测定了磺酰脲和三唑并嘧啶磺酰胺类除草剂的酸离解常数,进而采用回归分析方法探讨了测得的pK_a值与化合物的前沿轨道能级以及取代基效应之间的相关性,结果较为满意,从而证明从该体系测得的pK_a值用于构效关系分析是完全可行的.