Controlled-Potential and Derivative Polarography

Kelley, M.T.; Fisher, D. J.; COOKE, W.D.; Jones, H. C.

doi:10.1016/b978-1-4831-9844-6.50012-9

Cited by 12 publications

(5 citation statements)

References 9 publications

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“…For the simple reversible process, results from the numerical differentiation for the second and the third derivatives are identical to the results from the analytical formula of Eq. [5] and [6]. As post kinetics comes into play, all the curves in Fig.…”

Section: Resultsmentioning

confidence: 96%

“…Other parameters and variables have their usual meanings. The first-and second-order derivatives of the current with respect to E can be represented by the following two equations (14,19) i'(E) = -id(nF/RT)[e/ (1 + 9 [4] i"(E) = id(nF/RT)2[e(e -1)/(1 + 9 [5] Further successive differentiations of the second derivative yield third and fourth derivatives i"(E) = -id(nF/RT)3[ 9149 2 -4e + 1)/(1 + 9 [6] i"(E) = id(nF/RT)4[e( 9 3 -1I 9 ~ + 11 9 -1)/(1 + e) 5] [7] As one examines Eq. [1], the following relationship can be readily found between two values of current measured with two potentials which are opposite in sign i(-E) = id --i(E) [8] which simply imply that the current-potential expression has a point symmetry with the respect to a coordinate (0, id/2) when i and E are plotted on Cartesian coordinates, (x, y).…”

Section: Theorymentioning

confidence: 99%

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Higher‐Order Derivative Polarography/Voltammetry for a Reversible Electron Transfer Coupled with a Follow‐up Chemical Reaction

Kim

1990

J. Electrochem. Soc.

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Novel methods for the analysis of the first-and higher-order derivatives of polarographic current-potential curves are developed for a kinetically coupled electrode process, based upon theoretical expressions. This is accomplished by utilizing the asymmetries found in the peak shapes of the derivatives from adc polarogram/voltammogram. Fine features of the current-potential relationships, which cannot be easily recognized from the original i-E curves, are readily revealed in the first-and higher-order derivatives. Various parameters which characterize the peak asymmetry (such as ratios of half-peak widths, ratios of peak currents, and separations in peak potentials) are derived to obtain kinetic information on a reversible electron transfer coupled with a first-order post kinetics (i.e., ErCi). It is found that peaks that appear on the negative side of the potential in the second and third derivatives are much more sensitive to the post kinetics than those on the positive side. Suitabilities of various parameters as diagnostic tools for exploring a post-kinetic process are evaluated based on their sensitivity to the kinetics. The theory is applied to the benzidine rearrangement, for which derivatives are taken from a current-potential curve smoothed with a moving window average method. The agreement between theory and experimental results is reasonably good, although relatively large errors are observed in the values of the difference in peak potentials, primarily due to the present smoothing method used. However, the effects of a succeeding chemical reaction on the shapes of derivatives are indeed significant when the rate is high. Thus, the method can be utilized as a good technique for studying fast chemical reactions occurring after a reversible electron transfer.Most studies on derivatives polarography/voltammetry (1-25) have dealt with methods of obtaining derivatives (1-6, 14-18, 20), their applications in chemical analysis (6-11, 14, 16, 17, 21), and theories for uncomplicated simple electron transfer processes (12,14,18, 20, 22), but few studies have been made on applications of the method to study electrode kinetics (12, 25). The method still remains rather underdeveloped and unpopular compared to other voltammetric methods. Cyclic voltammetry (CV) dominates in studying electrode mechanisms, while several pulse methods dominate in chemical analysis. In earlier days (8-10), the derivative methods were plagued by low signalto-noise ratios and other instrumental artifacts (19); consequently, they have seldom been used in studying electrode kinetics. However, the advent of the recent (1980s) microprocessor-controlled electrochemical instruments provides better and faster signal-handling capabilities (such as signal-averaging, signal-smoothing, and differentiation). Digital signal output enables one to obtain the derivatives polarogram/voltammogram with good S/N ratios more easily than earlier analog instruments. In addition, derivative polarography/voltammetry has a unique and great advantage over other me...

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Section: Resultsmentioning

confidence: 96%

Section: Theorymentioning

confidence: 99%

Higher‐Order Derivative Polarography/Voltammetry for a Reversible Electron Transfer Coupled with a Follow‐up Chemical Reaction

Kim

1990

J. Electrochem. Soc.

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“…Voltammetric measurements were made with both a controlled-potential, fast-sweep differential polarograph (6), and an ORNL Model Q-1988-ES controlled-potential dc derivative polarograph (7,8). A special derivative circuit was designed for the faster scan rates employed.…”

Section: Methodsmentioning

confidence: 99%

Controlled-potential coulometry and voltammetry of manganese in pyrophosphate medium

Harrar¹,

Rigdon²

1969

Anal. Chem.

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A procedure has been developed for the determination of manganese by controlled-potential coulometry. The method is based on the oxidation of Mn(ll) to Mn(lll) at +1.05 to +1.10 V vs. SCE at a platinum electrode, in a supporting electrolyte of 0.25M Na4P207 at pH 2. Samples containing 0.5 to 10 mg Mn may be analyzed with an accuracy and precision of 0.1%. The method is applicable to a variety of materials; among the few interferences are Tl(l), As(lll), Ce(lll), and Sb(lll). Vanadium(IV) interference is eliminated

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“…The output of an electronic scan circuit has less noise than that of a motor-driven multiturn scan potentiometer (7). Electrolysis is carried out at controlled potential, which means that polarograms are recorded with an effective potential scale rather than an applied voltage scale.…”

Section: Instrumentationmentioning

confidence: 99%

“…Electrolysis is carried out at controlled potential, which means that polarograms are recorded with an effective potential scale rather than an applied voltage scale. The elimination by controlled-potential electrolysis of iR losses has significant advantages in improving derivative peak form, in eliminating distortion of wave form, particularly in high resistance media, and in increasing the resolution of regular waves or derivative peaks of close half-wave potential (7)(8)(9). The electronic performance of this polarographic instrument is sufficiently good and reliable that it does not adversely affect the reproducibility of wave or peak heights or the lowest concentration that may in practice be measured.…”

Section: Instrumentationmentioning

confidence: 99%

Capillary Behavior in High Sensitivity Polarography

Cooke¹,

Kelley²,

Fisher³

1961

Anal. Chem.

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5); therefore, Cpbim < 0.0158 Ch«(id if the solubility of lead in mercury is not to be exceeded. In these experiments Cb«(id = 5 X 10-W and the maximum permissible value of Cpbdn = 7.9 X 10_63/. Similar calculations for thallium, using the solubility of thallium in mercury as 27AM (12i, leads to Ctud 5 1.1 X 10~*M when Chíiid = 5 X 10-4'M. These conditions aie met by all of the experiments reported above.Efficiency of Plating of Pb(II) and T1(I). Equations 14 and 19 permit the calculation of the value N/C for Hg(II), Pb(II), and T1(I) in 0.13/ nitric acid. This ratio depends on the limiting currents for the various species, the time of plating, and the efficiency of plating. If the plating LITERATURE CITED

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Controlled-Potential and Derivative Polarography

Cited by 12 publications

References 9 publications

Higher‐Order Derivative Polarography/Voltammetry for a Reversible Electron Transfer Coupled with a Follow‐up Chemical Reaction

Higher‐Order Derivative Polarography/Voltammetry for a Reversible Electron Transfer Coupled with a Follow‐up Chemical Reaction

Controlled-potential coulometry and voltammetry of manganese in pyrophosphate medium

Capillary Behavior in High Sensitivity Polarography

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