人工神经元网络法提高毛细管电泳药物控制分析准确度的研究

研究了人工神经元网络法在毛细管电泳定量测定memantine中提高测定准确度 的可行性。在毛细管电泳法定量测定memantine的过程中，其浓度与峰高或峰面积 以及与二者和内标的比值均没有良好的线性关系。人工神经元网络具有很强的非线 性校正能力，其最大优点是无须对分离体系及组分的迁移行为预先予以了解。人工 神经元网络的输为memantine的峰高和峰面积，输出为memantine的浓度。通过实验 确定的网络结构为2：1：1型。由于人工神经元网络的通用性，该法也可用于毛细 管电泳在其他药物控制分析中改善定量分析的准确度。     

钛与3，5－二溴水杨基荧光酮配位反应的弛豫动力学研究

用跳浓弛豫法测定了微扰体系在不同浓度［Ｔｉ￣（４＋）］时的弛豫时间τ，拟定了合理的反应机理，并根据此机理导出了１／τ的函数表达式为１／τ＝ｋ［Ｈ４Ｒ］＿０／［Ｈ３Ｏ￣＋］＿０－４ｋ·Ａ∞／ε·［Ｈ３Ｏ￣＋］０，获得了配位反应的表现稳定常数Ｋ、表观速率常数ｋ及摩尔吸光系数ε；其中所得稳定常数Ｋ的值与用平衡移动法获得的结果相吻合，进一步证明了所拟机理的合理性。     

硼氢化钠还原法制备四羰基钴钠及羰基化反应

在常温压下，用ＮａＢＨ４作还原剂，由ＣＯ与ＣｏＣｌ２反应制备Ｎａ［Ｃｏ（ＣＯ）４］，其最佳的原料配比为ＮａＢＨ４：ＣｏＣｌ２＝２．５：１，反应温度为０－５℃，反应时间为２ｈ。产物经ＩＲ光谱鉴定，在１８９３ｃｍ＾－１处有一强吸收峰，此峰为［Ｃｏ（ＣＯ）４］＾－络合物离子中Ｍ－ＣＯ的特征吸收峰。     

C_(18)键合相吸附剂富集水中痕量苯并[a]芘

 １前言苯并［ａ］芘（ＢａＰ）是多环芳烃（ＰＡＨｓ）类致癌性最强的化合物之一，在饮用水中的含量不得超过０．０１μｇ／Ｌ。用固相萃取（ＳＰＥ）技术富集水样中痕量ＰＡＨｓ的系统研究以前已作过报道［１］，本文选择ＢａＰ为单一目标化合物，重点研究了水样离子强度和水样中ＢａＰ浓度水平对回收率的影响。２实验部分本文采用实验室合成水样，体积为１００ｍＬ。其它实验条件参见文献［１］。３结果与讨论研究表明，以硅胶为基质的Ｃ１８柱键合相是水中ＢａＰ的理想吸附剂，本实验在文献［１］的优化条件下，着重考察了水样离子强度和ＢａＰ浓度...     

H2O2—H2SO4体系电化学振荡行为的研究

Ｈ２Ｏ２参与的电化学振荡反应长期以来倍受人们的关注［１,２,３］,文献［１］报道了Ａｇ电极在Ｈ２Ｏ２－ＨＣｌＯ４水溶液中的电势振荡现象;文献［２］报道了Ｐｔ电极Ｈ２Ｏ２－Ｈ２ＳＯ４体系在控电流条件下的电势振荡,其实验的Ｈ２Ｏ２浓度范围为０．０２～０．...     

利用质谱—质谱法进行稠环芳烃化合物的结构解析

应用（ＥＩ）ＭＳ／ＭＳ法研究了吡啶并苯并蒽酮以及苯并苯并蒽酮类异构体的裂解方式及其与结构之间的相关性，探讨了不同异构体中由Ｍ＾ｉ＋产生的［Ｍ－Ｈ］＾＋、［Ｍ－ＨＣＮ］＾＋、［Ｍ－ＣＯＨ］＾＋、［Ｍ－ＣＯ］＾ｉ＋、［Ｍ－（ＣＯ＋２Ｈ）］＾ｉ＋以及［Ｍ－（ＣＯ＋ＨＣＮ）］＾ｉ＋（ｉ＝１，２）等１价及２价离子在ＭＳ／ＭＳ－ＣＩＤ谱上的强度差异和裂解方式，发现是否含有氮原子以及氮原子和苯环位置的差异，是支     

取代1H—吡唑并[5,1—C][1,2,4]三唑的合成

取代１Ｈ┐吡唑并［５，１┐Ｃ］［１，２，４］三唑的合成李春荣李仲杰（西安地质学院应用化学系７１００５４）（西北大学化学系西安７１００６９）１Ｈ－吡唑并［５，１－Ｃ］［１，２，４］三唑和１Ｈ－吡唑并［１，５～６］［１，２，４］三唑是新型彩色照相品成色剂...     

离子基碳——氧键断裂能量的研究（II）——负离子基的键能

合成了３个系列芳香类含碳－氧键的化合物，用循环伏安法测定了相关的氧化还原电势，通过热力学循环首次估测了负离子基的碳－氧键的断裂能量（ΔＨｃｌｅａｖ［Ｃ－Ｏ］＾－）。结果表明：得到１个电子形成负离子基可以活化碳－氧键。这与具有相同结构的正离子基的情况是一致的，但其活化程度略小。相关分析表明：ΔＨｃｌｅａｖ［Ｃ－Ｏ］＾－ｖｓ．（ΔＥｒｅｄ［Ｃ－Ｏ］＋ΔｐＫａ［ＨＡ］和ΔＨｃｌｅａｖ［Ｃ－Ｏ］＾＋ｖｓ．     

氯代甲苯异构体双电荷离子电子捕获诱导解离谱研究

研究了４种Ｃ７Ｈ７Ｃｌ异构体在７０ｅＶ电子轰击下产生的［Ｃ７Ｈ７Ｃｌ］＾２＋、［Ｃ７Ｈ６Ｃｌ］＾２＋．和［Ｃ７Ｈ５Ｃｌ］＾２＋ ３种双电荷离子的电子捕获诱导解离（ＥＣＩＤ）反应。分子离子的ＥＣＩＤ反应明显的邻位效应，表明其结构仍保持中性分子的结构特征；而由各异构体产生的［Ｃ７Ｈ６Ｃｌ］＾２＋．和［Ｃ７Ｈ５Ｃｌ］＾２＋离子异构化成同一结构。３种双电荷离子ＥＣＩＤ反应的产物与离子所带电子的奇偶性有关，     

三（2—苯并咪唑甲基）胺—锌（II）配合物模拟水解酶催化酯…

研究了三（２－苯并咪唑甲基）胺－锌（Ⅱ）配合物作为水解酶模拟物催化乙酸对硝基苯酯（ＮＡ）水解动力学。结果表明，催化水解速率对ＮＡ及配合物浓度呈一级反应。水解速率遵循速率方程ｖ＝（ｋｃａｔ［Ｚｎ］＋ｋＯＨ［ＯＨ＾－］＋ｋ０）［ＮＡ］。在２９８Ｋ，Ｉ＝０．１０ｍｏｌ／Ｌ ＫＮＯ３，０．０２ｍｏｌ／Ｌ Ｔｒｉｓ，４０％ＣＨ３ＣＮ水溶液中，二级反应速率常数ｋｃａｔ和ｋＯＨ分别为０．１２、１．４５ｍｏｌ＾－     

Comparative study on the analytical performance of three waveforms for the determination of several aminoglycoside antibiotics with high performance liquid chromatography using amperometric detection

A preliminary comparative study was carried out on the analytical performances of a new six-potential waveform and other two detection waveforms, triple-potential waveform and quadruple-potential waveform. The analytical performances compared included signal response, background noise, signal/noise ratio and signal stability. Compared with triple-potential waveform and quadruple-potential waveform, the new six-potential waveform had higher signal response, signal/noise ratio, and sensitivity. As for determination reproducibility, the six-potential waveform also exhibited a slightly better performance than the other two waveforms. Under the selected experimental conditions based on the six-potential waveform, there is a linear correlation between peak area and concentration over two to three orders of magnitude for nine aminoglycoside antibiotics with a correlation coefficients better than 0.998 and the detection limits measured as three times the peak height signal-to-noise ratio for the nine aminoglycoside antibiotics were in the range of 0.0198-0.889 microg/mL. The proposed method had been used to analyze real gentamicin sulphate drug sample.     

Determination of bromate in sea water using multi-dimensional matrix-elimination ion chromatography

A multi-dimensional matrix-elimination ion chromatography approach has been applied to the determination of bromate in seawater samples. Two-dimensional and three-dimensional configurations were evaluated for their efficacy to eliminate the interference caused by the high concentration of ubiquitous ions present in seawater, such as chloride and sulfate. A two-dimensional approach utilising a high capacity second dimension separation comprising two Dionex AS24 columns connected in series was applied successfully and permitted the determination of bromate in undiluted seawater samples injected directly onto the ion chromatography system. Using this approach the limit of detection (LOD) for bromate based on a signal to noise ratio of 3 was 1050 μg/L using a 500 μL injection loop. Good linearity was obtained for bromate with correlation coefficients for the calibration curves of 0.9981 and 0.9996 based on peak height and area, respectively. A three-dimensional method utilising two 10-port switching valves to allow sharing of the second suppressor and detector between the second and third dimension separations showed better resolution and detection for bromate and reduced the LOD to 60 μg/L for spiked seawater samples. Good linearity was maintained with correlation coefficients of 0.9991 for both peak height and area. Ozonated seawater samples were also analysed and exhibited a non-linear increase in bromate level on increasing ozonation time. A bromate concentration in excess of 1770 μg/L was observed following ozonation of the seawater sample for 120 min. Recoveries for the three-dimensional system were 92% and 89% based on peak height and area, respectively, taken over 5 ozonated samples with 3 replicates per sample.     

Analysis of peak asymmetry in chromatography

The knowledge of the symmetry of chromatographic peaks is extremely important regarding the digital signal processing. The significant deviation of the peak shape from the symmetrical peak makes hardly possible the acquisition of chromatographic signal information, such as the retention time, the peak area, the peak width at half peak height, the peak overlapping, etc. In the literature one can find many methods for the determination of the asymmetry factor. For example it is suitable to calculate the skewness from the third central moment. However in case of noisy baseline the value of the skewness oscillates highly depending on the number of points used for the mathematical calculation. In this work a new method is presented for the determination peak shape asymmetry. We order mathematical function to the chromatographic peaks by fitting, and then symmetrical curve is generated with the same peak maximum position and height, the peak width is fitted. The difference of the two functions is constituted and areas of the data differences are calculated, which are really characteristics of the peak asymmetry. Correlation between the area of the difference signal and the asymmetry factor is established. The method was applied for different types of chromatographic peak shapes and the results were interpreted.     

Use of differentiation and smoothing in linear-sweep and staircase stripping voltammetry of some metals

Two methods of signal smoothing were considered: square-wave (moving average) and triangular (weighted average) filters. It was found that smoothing by these two filters did not distort noticeably the signal shape and the linearity of calibration plots. Calibration plots for several series of analytical signals of heavy metals were studied. Analytical signals were obtained by stripping voltammetry using a mercury thin-film electrode and processed using the peak area, the peak height, and the range of the extrema of the first and second peak derivatives. It was shown that, for staircase stripping voltammetry, the linearity of calibration plots decreases substantially in this series of signal processing methods. For linear sweep, calibration plots were linear over the entire concentration range for all signal-processing methods. Presented at the V All-Russian Conference with the Participation of CIS Countries on Electrochemical Methods of Analysis (EM A-99), Moscow, December 6–8, 1999.     

岛津C－R2A全自动高效液相色谱分析程序的设计

利用Ｃ－Ｒ２Ａ色谱处理机的编程功能，实现了液相色谱法（主机为ＬＣ－４Ａ和ＳＩＬ－２ＡＳ自动进样器）全自动分析，即通过程序实现按设定的样品顺序、进样量、重复次数对样品进行测定，每个样品分析完后，进行数据处理，并打印出结果表     

Experimental and theoretical intensities for graphite furnace atomic emission spectrometry

A constant-temperature atomizer in which tube dimensions and heating modes could be varied was used to experimentally measure atomic emission intensities for 12 elements. These results were compared with intensities calculated from theoretical expressions describing peak height and peak area emission signals. The best agreement between experimental and calculated intensities was obtained for a 1.8 cm long atomizer configuration providing both spatial and temporal isothermality, and using peak area signal evaluation.     

Observation of a physical matrix effect during cold vapour generation measurement of mercury in emissions samples

The observation of a physical matrix effect during the cold vapour generation–atomic fluorescence measurement of mercury in emissions samples is reported. The effect is as a result of the different efficiencies of liberation of reduced mercury from solution as the matrix of the solution under test varies. The result of this is that peak area to peak height ratios decease as matrix concentration increases, passing through a minimum, before the ratio then increases as matrix concentration further increases. In the test matrices examined – acidified potassium dichromate and sodium chloride solutions – the possible biases caused by differences between the calibration standard matrix and the test sample matrix were as large as 2.8% (relative) representing peak area to peak height ratios for calibration standards and matrix samples of 45 and 43.75, respectively. For the system considered there is a good correlation between the density of the matrix and point of optimum liberation of dissolved mercury for both matrix types. Several methods employing matrix matching and mathematical correction to overcome the bias are presented and their relative merits discussed; the most promising being the use of peak area, rather than peak height, for quantification.     

The use of DSC curves to determine the acetylation degree of chitin/chitosan samples

The use of DSC curves is proposed as an alternative method to determine the degree of N-acetylation (DA) in chitin/chitosan samples, based in both peak area and height of the decomposition signal. Samples with DA from 74 to 16% were prepared from a chitin commercial sample and the DA was determined by ¹H NMR, ¹³C CP/MAS NMR and IR spectra. The effect of water content, heating rate, sample mass and gas flow on the DSC peaks were evaluated and optimized. Using optimized conditions a linear relationship between peak area and height with the DA could be achieved with linear correlation coefficients of −0.998 and −0.999 (n = 7), respectively. The calibration graphs were used to determine the DA of a commercial chitosan sample with relative errors ranging from 2 to 3% for both peak area and peak height, when compared with the DA determined by ¹H NMR method.     

Peak Area: the Instrumental Datum to Improve the Determination at Ultratrace Level Concentration of Mercury(II) at Gold Electrode

Peak area as instrumental datum for determining the concentration of metals in solution instead of peak height is proposed for analytical voltammetric determinations. In the case of species present at ultra‐trace concentration level or having low reversibility degree electrodic processes, the employment of peak area permits to achieve limits of detection lower even more of one order of magnitude. The present work shows the possibility of determining, at ultratrace level concentration, mercury(II) by differential pulse anodic stripping voltammetry (DPASV).     

Effective on-line coupling of HPLC and flame-AAS by means of hydraulic high pressure nebulization

Summary Hydraulic high pressure nebulization is used as an effective way of on-line coupling of HPLC to flame-AAS for speciation of metal compounds in the ng range. Compared to coupling with a conventional nebulizer a signal enhancement by a factor of 7.5 (peak height) and 10.1 (peak area) for copper is obtained. Using an injected volume of 50 μL the detection limits for Cu, Fe, Ni and Cd are below 0.1 μg/mL (=5ng) and for Mg below 0.01 μg/mL (=0.5ng). The effects of HPLC flow-rate and nebulization nozzle diameter on the signal peak height have been investigated. The performance of the system is demonstrated using speciation of iron. A base-line separation of Fe(II) and Fe(III) is achieved within two minutes. Also species changes (Fe acetate to Fe citrate) can be analysed using the proposed system.