交流示波极谱法中i~f-E曲线的研究 7:基于i~f-E曲线的定量分析方法

本文提出基于i~f-E曲线的定量分析方法,并在自行研制的微机电化学数据采集系统上,测定了微量的Tl^+、Pb^2+、Cd^2+、Zn^2+、Mn^2+和Ga^3+.结果表明,与经典的dE/dt-E曲线方法相比,i~f-E曲线方法的准确度提高了2-5倍、灵敏度提高了一个数量级.     

交流示波极谱法中i~f-E曲线的研究 8:"电极/溶液"界面动态双电层微分电容的快速测量

"电极/溶液"界面动在记双电层微分电容是电极过程动力学中一个重要的物理量,但其测量方法,多数仍停留在对逐一测定的数据点进行作图分析上.本文以i~f-E曲线上电流峰的理论公式为基础,提出了一个快速测量"电极/溶液"界面动态双层微分电容的新方法.     

交流示波极谱法中i~f-E曲线的研究 8:"电极/溶液"界面动态双电层微分电容的快速测量

"电极/溶液"界面动在记双电层微分电容是电极过程动力学中一个重要的物理量,但其测量方法,多数仍停留在对逐一测定的数据点进行作图分析上.本文以i~f-E曲线上电流峰的理论公式为基础,提出了一个快速测量"电极/溶液"界面动态双层微分电容的新方法.     

交流示波极谱法中i_f-E曲线的研究——Ⅶ.基于i_f-E曲线的定量分析方法

本文提出基于i(?)-E曲线的定量分析方法,并在自行研制的微机电化学数据采集系统上,测定了微量的Tl~+、Pb~(2+)、Cd~(2+)、Zn~(2+)、Mn~(2+)和Ga~(3+).结果表明,与经典的dE/dr-E曲线方法相比,i(?)-E曲线方法的准确度提高了2—5倍、灵敏度提高了一个数量级.     

硫酸亚铁及氯化铁与硫酸亚铁混合溶液与氢氧化钠溶液反应的沉淀pH曲线的测定及分析

应用手持技术pH传感器,测定了NaOH溶液滴定FeSO4溶液的t-pH曲线,应用origin 9.0分析实验数据,探讨了空气对Fe2+沉淀pH的影响;通过测定并分析FeSO4溶液滴定NaOH溶液的pH曲线,发现了溶液最终pH受金属离子水解程度的影响;通过测定并分析NaOH溶液滴定FeCl3和FeSO4混合溶液的pH曲线,探讨了Fe2+和Fe3+的互相影响,使其沉淀pH范围发生变化;通过测定并分析FeCl3和FeSO4混合溶液滴定NaOH溶液的pH曲线,验证了Fe2+和Fe3+的水解程度不同,Fe （OH）3和Fe （OH）2的存在条件也不一样。     

ICP—AES分析的线性回归校准曲线

本文对ICP-AES分析中2种线性回归方法的校准曲线作了比较和讨论。对大多数元素而言,用加权法得到的校准曲线的斜率比不加权校准曲线的斜率略大,减小3校准曲线在低浓度部分的弯曲,曲线明显优于不加权校准曲线。将2种方法得到的校准曲线进行比较时,应将剩余标准偏差(或剩余变差平方和)及曲线截距等加以综合考虑。用含零标的标准系列制作校准曲线可使曲线的截距更接近原点,有利于提高在低浓度部分校准分析的准确性。     

直读光谱分析工作曲线中标样取值的认识

目前 ,在直读光谱分析中许多工厂自制了一些控样 ,用控样参与绘制工作曲线 ,校正待分析的试样。但也有不少单位由于种种原因 ,至今没有制作控样 ,或者控样并没有参与绘制工作曲线 ,这样 ,对工作曲线中标样取值的认识应该引起注意。最理想的光谱分析工作曲线 ,是参与绘制工作曲线的每一个点 ,即每一块标样有关的激发点 ,利用高斯 约登 (ＧａｓｓＪｏｒｄａｎ)权重最小二乘法 ,以光强比与其对应的浓度 ,用曲线关系式 :Ａ(ＩＲ) 3+Ｂ(ＩＲ) 2+Ｃ(ＩＲ) +Ｄ =%ｃｏｎｃ ,经过回归拟合之后 ,原标样的元素含量的定值与工作曲线上回归拟合的计算值…     

if～E交流示波极谱法的研究

本文提出了一种扣除交流示波极谱中充电电流的方法,设计了用微型计算机控制有关仪器的线路。测定了Tl⁺、In³⁺、Cd²⁺、pb²⁺、Zn²⁺等离子的法拉第电流和去极剂浓度的关系曲线,提高了交流示波极谱的灵敏度。     

滴定曲线与缓冲容量曲线、敏锐指数曲线并联讨论滴定规律

为了研究平衡的变化规律,我们曾撰文介绍滴定曲线与滴定过程型体分布图并联的方法。本文将讨论滴定曲线与滴定液的缓冲容量曲线和敏锐指数曲线并联研究平衡的方法。理论推导 1.强碱滴定酸参照文献[2]可以得出,以浓度为C的NaOH溶液滴定浓度为C_0、体积为V_0的n元酸H_nB,当加入NaOH V时滴定曲线方程为:     

水+甲烷系统的气液相边界曲线和临界曲线

采用带有蓝宝石视窗和磁力搅拌的可变体积高压斧得出了水+甲烷系统的气液相边界曲线和临界曲线. 实验温度为433.0-633.0 K, 实验压力为30.00-300.00 MPa. 实验确定了甲烷在富水区的亨利系数, 结果显示, 在433.0-603.0 K的温度范围内, 此亨利系数随着温度的升高而下降. 本文还研究了甲烷+水系统的气液分配比以及偏摩尔溶解焓和偏摩尔溶解熵数据. 结果发现, 甲烷和水的内聚能密度差别很大.     

Antilg i1-E曲线上的示波伏安滴定法

i_1-E曲线示波伏安滴定法是一种新的灵敏、准确的滴定分析方法。为进一步提高滴定终点指示的灵敏度,本文在产生i_1-E曲线的线路中,增加了正反馈电路和反对数电路,并提出了Antilg i_1-E曲线上的示波伏安滴定法。用EDTA或EGTA滴定了Ga~(3+)、Cd~(2+)、Zn~(2+)、Ni~(2+)、Co~(2+)等离子,并测定了铜锰合金中的锰,效果较好。     

反对数简易示波伏安法的研究

本文在产生简易示波伏安曲线的实验线路中增加了反对数线路，提出了反对数简易示波伏安法，用此方法进行了络合滴定及实际样品的测定，结果符合分析要求。     

Investigations on if-E Curve in Cyclic Derivative Chronopotentiometry(Ⅵ)——Theoretical Equations of if-E Curves in the Case of Quasi-reversible and Irreversible Electrode Reactions

The theory of if-E curve in cyclic derivative chronopotentiometry is presented. Theoretical equations of if-E curves in the case of quasi-reversible and irreversible electrode reactions are deduced respectively.     

简易示波伏安法的研究—药物滴定分析

本文运用简易示波伏安法成功地进行了药物滴定分析,测定了两种新药胃复康及氢溴酸苯甲托品,获得了满意的结果。这种方法克服双池伏安法仪器复杂等缺点,使用一个电解池和一个很简单的线路也可获得示波伏安图。它能部分地扣除充电电流,终点时峰形变化敏锐。     

Simultaneous determination of Cu2+, Zn2+, Cd2+, Hg2+ and Pb2+ by using second-derivative spectrophotometry method

A new method of simultaneous determination of Cu2+, Zn2+, Cd2+, Hg2+ and Pb2+ is proposed here by using the second-derivative spectrophotometry method. In pH=10.35 Borax-NaOH buffer, using meso-tetra (3-methoxyl-4-hydroxylphenyl) porphyrin ([T-(3-MO-4-HP)P]) as chromomeric reagent, micelle solution was formed after Tween-80 surfactant was added into the solution containing Cu2+, Zn2+, Cd2+, Hg2+ and Pb2+ ions. The original absorption spectrum of the above complexes was obtained after heating in the boiling water for 25 min. The second-derivative absorption peaks of five metal-porphyrin complexes can be separated from the original absorption spectrum by using chemometric tool. In this way, Cu2+, Zn2+, Cd2+, Hg2+ and Pb2+ ions can be determined simultaneously. Under the optimal conditions, the linear ranges of the calibration curve were 0-0.60, 0-0.60, 0-0.40, 0-0.80 and 0-0.48 μg mL(-1) for Cu2+, Zn2+, Cd2+, Hg2+ and Pb2+, respectively. The molar absorptivity of these color systems were 1.38×10(5), 1.01×10(5), 3.24×10(5), 1.07×10(5) and 1.29×10(5)Lmol(-1)cm(-1). The method developed in this paper has advantages in selectivity, sensitivity, operation and can effectively resolve spectra overlapping problem. This method has been applied to determine the real samples with satisfactory results.     

分析检测N2O4中的相当水含量的核磁共振法

介绍了核磁共振(NMR)法在N2O4中相当水含量分析检测方面的应用,包括标准曲线核磁共振法,内标物核磁共振法,重点叙述了富氘纯物质作为内标物检测N2O4中相当水含量时的准确性和灵敏度。     

Use of the Second Derivative of TG Curves for Investigation of the Exchanged Interlayer Cation in Montmorillonite

Various cation-exchanged montmorillonites (Li+, Na+, Ba2+, Mg2+, Ca2+, Mn2+, Co2+, Cu2+, Ag+, Cd2+, Hg2+, Al3+, Pb2+ and NH4+) were prepared from calcium montmorillonite and their properties were studied by means of X-ray diffraction and thermal analysis. The two methods give information on the cation exchange in the interlayer space only. X-ray diffraction studies at room temperature are mainly suitable for estimation of the exchange of cations of different valencies. At 500°C, when the structure is completely collapsed, the d value of montmorillonite depends on the non-hydrated ionic radius of the interlayer cation, but the measurement interval is limited for fine interpretation. The thermoanalytical method is suitable for a better distinction of different exchangeable cations of higher hydration energy on the basis of the DTG or DDTG curve. This revised version was published online in July 2006 with corrections to the Cover Date.     

Progress in neutron activation analysis for uranium

A new type of extractant, sym-dibenzo-16-crown-5-oxyhydroxamic acid (HL) is introduced. The extractions of UO22+, Na+, K+, Sr2+, Ba2+ and Br- were studied with HL in chloroform. The results obtained show that UO22+ can be quantitatively extracted at pH values above 5, whereas the extractions of K+, Na+, Sr2+, Ba2+ and Br- are negligible in the pH range of 2 - 7. The dependence of the distribution ratio of U(VI) on both the concentration of the HL and pH are linear, and they have the same slope of 2. This suggests that U(VI) appears to form a 1:2 complex with ligand. Uranium(VI) can be selectively separated and concentrated from interfering elements such as Na, K, Sr and Br by solvent extraction with HL under specific conditions. The recovery of uranium is nearly 100% and the radionudear purity of uranium is greater than 99.99%. Therefore, neutron activation analysis has greatly improved the sensitivity and accuracy for the detection of trace uranium from seawater.     

Spectrofluorometric determination of hydrogen peroxide based on oxidative catalytic reactions of p-hydroxyphenyl derivatives with metal complexes of thiacalix[4]arenetetrasulfonate on a modified anion-exchanger.

The peroxidase-like catalytic activity of metal complexes of thiacalix[4]arenetetrasulfonate (TCAS[4]) on a modified anion-exchanger (Me(n+)-TCAS[4]A-500; Me(n+) = H2, Fe3+, Fe2+, Mn3+, Co3+, Co2+, Cu2+, Zn2+, Ni2+) for the oxidation of p-hydroxyphenyl derivatives to produce fluorescent substances in the presence of hydrogen peroxide has been investigated. Among the Me(n+)-TCAS[4]A-500 tested, Fe(3+)-TCAS[4]A-500 exhibited the highest level of catalytic activity for the oxidation of p-acetoamidophenol in a carbonate buffer solution of pH 10. The catalytic activity of Fe(3+)-TCAS[4]A-500 was then used for the spectrofluorometric determination of hydrogen peroxide. The calibration curve for the Fe(3+)-TCAS[4]A-500 method was linear over a range spanning from 0.1 to 5.0 microg of hydrogen peroxide in a 1.0 ml sample solution.