首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到18条相似文献,搜索用时 109 毫秒
1.
研究了络合吸附催化不可逆体系受前行化学反应控制(K<<1)和不受前行化学反应控制(K>>1)两种情况下的循环叠式方波伏安法的电流理论,并进行了实验验证,讨论了电流特性,获得区分K<<1和K>>1的判据。对于上述体系的测定,循环叠式方波伏安法的灵敏度比普通差式采样方波伏安法高一个数理级以上。  相似文献   

2.
对位叠式循环方波伏安法:Ⅰ.简单可逆电极体系   总被引:3,自引:0,他引:3  
莫金垣  蔡沛祥 《分析化学》1995,23(3):250-254
本文提出叠式循环方波伏安法和对位叠式循环方波伏安法,对简单可逆电极体系的理论作了推导和验证,经对各种电流的比较,发位叠式循环方波伏安法有较多的优点。较之其它方波伏安法灵敏。  相似文献   

3.
推导出不受前行化学反应控制的络合吸附不可逆过程叠式循环方波伏安法的电流及其卷积和导数方程,系统地研究了各电流一有关参数的关系,给出了峰电势表达式,并进行了实验验证。该理论同样适用于简单吸陵不可逆过程。  相似文献   

4.
推导出受前行化学反应控制的络合吸附不可逆体系叠式循环方波伏安法的电流方程及其各阶导数卷积方程,研究了各峰电流与诸因素的关系,并推导出峰电势表达式。理论推导与实验结果一致。  相似文献   

5.
推导出不受前行化学反应控制的络合吸附不可逆过程叠式循环方波伏安法的电流及其卷积和导数方程,系统地研究了各电流峰形,各峰电流与有关参数的关系,给出了峰电势表达式,并进行了实验验证。该理论同样适用于简单吸附不可逆过程。  相似文献   

6.
莫金垣  张润建 《分析化学》1995,23(3):255-258
本文提出平行催化体系的对位叠式循环方波伏安法,并对共作了系统的研究,推导了这一方法的催化电流理论方程,并用验验证这理论的正确性,得到其各脉冲电流皆为同方向,对位叠式循环催化电流相当于将电流叠加4次,而波形不受方波幅度大小的影响,因而灵敏度和分辨率有较大提高,优于其它方波伏安法。  相似文献   

7.
叠式循环阶梯脉冲伏安法:Ⅰ.简单可逆电极体系   总被引:1,自引:0,他引:1  
本文提出循环阶梯脉冲伏安法和对位叠式循环阶梯脉冲伏安法,推导出简单可逆电极体系的电流方程,研究了峰电流与诸因素的关系,并进行了实验验证,发现对位叠式循环阶梯脉冲伏安法有较多的优点  相似文献   

8.
吸附方波伏库仑法研究:I.简单吸附体系   总被引:1,自引:1,他引:0  
对简单吸附体系方法伏库仑法进行了理论推导和实验验证,讨论了各种因素对伏库仑曲线的影响,研究表明,对于简单吸附体系,方法伏库仑法的灵敏度和检测限均优于方波伏安法。  相似文献   

9.
对络合吸附体系分别推导了前行化学反应平衡常数K1和K1两种情况的方波伏库仑法的电量方程及作了实验验证,获得判别这两种络合吸附体系的理论依据。讨论了各种因素对伏库仑曲线的影响,并由实验比较了方波伏库仑法和方波伏安法的检测限。  相似文献   

10.
对络合吸附体系分别推导了前行化学反应平衡常数K〈〈1和K〉〉1两种情况的方波伏库仑法的电量方程及作了实验验证,获得判别这两种络合吸附体系的理论依据,讨论了各种因素对估库仑曲线的影响,并由实验比较皮伏库仑法和方波伏安法的检测限。  相似文献   

11.
谢天尧  莫金垣 《分析化学》1993,21(12):1387-1391
本文报道了在不可逆电极过程的强催化体系中,当采用快速方波扫描时,正、逆向电流将出现峰形。依据实验结果,提出了“迁出-进入”的等浓度面理论模型,推导了并讨论了电流方程式。结果表明,文中提出的理论能较好地说明实验结果。  相似文献   

12.
研究导电聚合物的电荷传输机制与速度对于其在应用方面的研究极为重要[‘].例如在电池的研究中,充放电的速度决定于导电聚合物的电荷传输速度;在电致变色器件的研究中,响应时间也是决定于导电聚合物在氧化还原态间的变化速度,即电荷传输速度.显然较低的电荷传输速度不利于器件的实用化,因此人们必须找到一种能够迅速准确评价电荷传输速度的方法,由于导电聚合物是一个特殊的体系,用一般的电化学方法对其电荷传输速度进行测定时常常遇到这样或那样的问题[‘j.一般说来,导电聚合物的氧化还原过程中均伴随着抗衡离子的运动.体系…  相似文献   

13.
Theory for cyclic square wave voltammetry of electrode reactions with chemical reactions preceding the electron transfer is presented. Theoretical voltammograms were calculated following systematic variation of empirical parameters to assess their impact on the shape of the voltammogram. From the trends obtained, diagnostic criteria for this mechanism were deduced. When properly applied, these criteria will enable non‐experts in voltammetry to assign the electrode reaction mechanism and accurately measure reaction kinetics.  相似文献   

14.
A direct voltammetric method for the rapid determination of butylated hydroxytoluene has been developed. The procedure utilizes a hydrolyzed cellulose acetate film in intimate contact with a glassy carbon electrode and square wave voltammetry. The coated electrode prevents passivation due to adsorption of polymeric oxidation products by way of a size exclusion principle. BHT solutions containing lipid-like surfactants can be analyzed without the need for frequent resurfacing of the electrode.  相似文献   

15.
A sensitive voltammetric method is presented for the determination of trace amounts of total chromium (Cr(III) and Cr(VI)) in natural waters, employing the square wave mode. The method is based on the preconcentration of the Cr(III)-TTHA complex by adsorption at the HMDE at the potential of –1.0 V vs. Ag/AgCl. The adsorbed complex is then reduced producing a response with a peak potential of –1.29 V and the peak height of the Cr(III) reduction is measured. The catalytic action of the nitrate ions on the Cr(III)-TTHA reduction has been elucidated using cyclic voltammetry. The adsorption of chromium complexes at the HMDE was investigated using out-of-phase a.c. voltammetry and the potential range of adsorption was determined.Based on these investigations optimal conditions for the determination of the total chromium concentration in the range 155–2000 ng 1–1 have been established. The determination limit is 15 ng 1–1 and the RSD is 3.5% for chromium concentrations 200 ng 1–1.The usefulness and wide scope of this method for reliable and highly sensitive chromium analysis down to the ultra trace levels existing in various types of natural waters is demonstrated by determinations of the total chromium content in lake, sea and rain water.  相似文献   

16.
A rapid and precise method has been developed for the determination of hydrazine in polyvinylpyrrolidone (PVP). Hydrazine is converted to salicylaldazine by reaction with salicylaldehyde. After extraction, the azine is reduced at –1.56 V versus the SCE at the hanging drop electrode. Detection is accomplished using square wave voltammetry and comparison to an external salicylaldazine standard. The described procedure can detect as little as 70 ng/g hydrazine in PVP.  相似文献   

17.
《Electroanalysis》2002,14(23):1654-1660
It was found that melatonin could be incorporated and accumulated on the surface of the glassy carbon electrode which was activated electrochemically by pretreatment in sodium hydroxide solution by means of cycling the potential well into the positive limit of the solvent. In Britton‐Robinson buffer solution (pH 6.7), melatonin gave a sensitive oxidation wave at a potential of +0.65 V (vs.Ag/AgCl) by using Osteryoung square‐wave stripping voltammetry (OSWSV). The oxidation process has been shown to be irreversible and adsorption‐controlled at this electrode by means of cyclic voltammetry and linear sweep voltammetry. A chronocoulometric characterization of the adsorption characteristics of melatonin at this electrode is also presented. The factors affecting the peak current were optimized, and the dependence of peak currents on the concentration of melatonin was found to be linear in the range 8.0×10?7?1.0×10?5 mol L?1. A detection limit of 5.0×10?8 mol L?1 was obtained (signal‐to‐noise ratio of 3). This method was applied to the assay of melatonin in tablets and capsules with good recoveries (98–100%).  相似文献   

18.
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号