Oxidation linear sweep

The oxidation linear sweep (Figure 5) has one major, broad peak which depends on the switching potential X. If X =-1.0 volt, the peak is large if X=-0.3, it is absent. Thus, the structures oxidized to form that peak are generated at rather cathodic potentials. ... 

A simple, rapid and seleetive eleetroehemieal method is proposed as a novel and powerful analytieal teehnique for the solid phase determination of less than 4% antimony in lead-antimony alloys without any separation and ehemieal pretreatment. The proposed method is based on the surfaee antimony oxidation of Pb/Sb alloy to Sb(III) at the thin oxide layer of PbSOyPbO that is formed by oxidation of Pb and using linear sweep voltammetrie (LSV) teehnique. Determination was earried out in eoneentrate H SO solution. The influenee of reagent eoneentration and variable parameters was studied. The method has deteetion limit of 0.056% and maximum relative standard deviation of 4.26%. This method was applied for the determination of Sb in lead/aeid battery grids satisfaetory. 

Studies of the linear sweep and cyclic voltammetric behavior of N-methyl-ated xanthines 35 -37> reveals that they undergo electrochemical oxidation over a fairly wide pH range at the PGE (Table 1). All but three of the xanthines studied show just a single voltammetric oxidation peak, although it is prob-... 

The oxidation-reduction cycles (ORCs) necessary to roughen the electrode surface are generally performed as potential steps, linear sweeps with a... 

Except for very electron-rich donors that yield stable, persistent radical cations, the ox values are not generally available.64 Thus the cation radicals for most organic donors are too reactive to allow the measurement of their reversible oxidation potentials in either aqueous (or most organic) solvents by the standard techniques.65 This problem is partially alleviated by the measurement of the irreversible anodic peak potentials E that are readily obtained from the linear sweep or cyclic voltammograms (CV). Since the values of E contain contributions from kinetic terms, comparison with the values of the thermodynamic E is necessarily restricted to a series of structurally related donors,66 i.e.,... 

The redox characteristics, using linear sweep and cyclic voltammetry, of a series of (Z)-6-arylidene-2-phenyl-2,3-dihydrothiazolo[2,3-r][l,2,4]triazol-5(6//)-ones 155 (Figure 24) have been investigated in different dry solvents (acetonitrile, 1,2-dichloroethane, tetrahydrofuran (THF), dimethyl sulfoxide (DMSO)) at platinum and gold electrodes. It was concluded that these compounds lose one electron forming the radical cation, which loses a proton to form the radical. The radical dimerizes to yield the bis-compound which is still electroactive and undergoes further oxidation in one irreversible two-electron process to form the diradical dication on the newly formed C-C bond <2001MI3>. 

The forward half of the CV is identical to a linear-sweep voltammogram. The back half of the CV represents the reverse electron-transfer processes occurring at the working electrode if the peak on the forward limb of the CV represents the oxidation reaction, Fe + -> Fe -I- e, then the reverse limb represents the reduction reaction, Fe e Fe. V/e can gain much information if the peak current of the reverse limb is smaller than the peak current during the forward part of the cycle (see next section). Such information cannot be obtained in a LSV experiment because no reverse limb is traversed. 

The radical-cation reacts with the nucleophile to form a radical intermediate, which is then oxidised to the carbonium ion, usually at a potential less positive than that required for die first electron transfer process. However, enol ethers show two one-electron waves on linear sweep voltammetry. The firet wave is due to the formation of the radical-anion and the second wave to oxidation of carbon radical intermediates to the carbonium ion. 

The electrochemical behavior of chlorpromazine hydrochloride in 0.2M H2SO4 was studied by cyclic and linear sweep voltammetry at an oxidized and a non-oxidized ruthenium wire electrode [173]. Preparation of a stable and permanent coating of RuOj on the electrode was very time-consuming, but the resulting curves were highly reproducible. The... 

In linear sweep voltammetry, the potential is varied linearly versus time, and current peaks are registered in correspondence to oxidation or reduction (depending on the potential variation verse) of the analytes. The potential value associated to a peak is characteristic of the specie being oxidizing or reducing, while the peak height can be employed for quantitative purposes. 

Fig. 13 Linear sweep voltammetry (LSV) oxide reduction profile for an Au electrode after polarization at p = 2.23 V (RH E) for tp = 900 s in 0.50 M aqueous KOH solution ...

Fig. 9.5 Simultaneously measured CV curve (a), absorption potential curve (b), and its derivative with respect to scan potential (c), for the cyclic linear sweep oxidation of tri-p-anisylamine at a vapor-deposited platinum OTE in 0.1 M Et4NCI04-AN [8].

Recent studies describe the use of cyclic voltammetry in conjunction with controlled-potential coulometry to study the oxidative reaction mechanisms of benzofuran derivatives [115] and bamipine hydrochloride [116]. The use of fast-scan cyclic voltammetry and linear sweep voltammetry to study the reduction kinetic and thermodynamic parameters of cefazolin and cefmetazole has also been described [117]. Determinations of vitamins have been studied with voltammetric techniques, such as differential pulse voltammetry for vitamin D3 with a rotating glassy carbon electrode [118,119], and cyclic voltammetry and square-wave adsorptive stripping voltammetry for vitamin K3 (menadione) [120]. 

Figure 3.13 Electrochemical oxidation of HOOH and reduction of its products at GC electrodes in MeCN (0.1 M TEAP) (a) linear-sweep anodic voltammograms for (A) 0, (B) 0.3, (C) 1.7, and (D) 3.3 mM HOOH (scan rate 2 V min-1 electrode area, 0.46 cm2) (b) rotated-ring electrode cathodic voltammogram (scan rate 10 mV s-1) of the product from the oxidation of 4 mM HOOH at the rotated-disk electrode (rotation rate 1600 rpm) for (A) ED disconnected, and (B) En = +2.6 V versus SCE (c) rotated-ring electrode cathodic voltammogram (scan rate 10 mV s-1) of the products from the oxidation of 1 mM HOOH at the rotated-disk electrode (rotation rate 4900 rpm) for (A) disconnected and (B) ED = +2.6 V versus SCE.

Scheme I. Concept of a two-terminal microsensor showing two possible idealized responses to a species L which binds to the indicator molecule M. A) The linear sweep voltammograms reveal a difference between the current peaks for oxidizing the reference molecule, R, and M or M-L. The position of the current peak along the potential axis, V, is variable and depends on the concentration of L. B) The linear sweep voltammograms reveal a decrease in amplitude for the current peak assigned to M and proportional growth of a new current peak assigned to M-L.

Fig. 11.4. Typical linear sweep voltammogram (LSV) data for the ICA film in background electrolyte LSV data is recorded (a) initially after film formation (b) after cycling and repeated holding first at a potential corresponding to complete oxidation (1 hour) and then at a potential for complete reduction of the film (1 hour) for an overall period of 2 days (c) same as (b) but for 5 days (d) in 0.1 M NaCI04 rather than 0.1 M LiCI04. The voltage sweep rate was 2.5 mV/s"1 in all cases.

The dimers D, 4 readily undergo electrochemical, irreversible, oxidation under anaerobic conditions on the pyrolytic graphite electrode, with oxidation peak potentials, determined by linear sweep voltammetry on 1 mM solutions, as shown in Table V). Note the much lower values of E for dimers Dj 3, relative to D4, testifying to the greater susceptibility of the former to oxidation. 

High-speed linear-sweep voltammetry (LSV) or linear potential sweep chronoamperometry (top) potential waveform (bottom) current response. The areas between the solid lines and the dotted lines measure approximately the charge transferred in the oxidation or reduction. 

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