Differential pulse voltammograms electrode

FIG. 13 Differential pulse voltammograms for Au electrode modified with el6S-tl9-T12Fc ternary complex (filled circle) and el6S-ml9-T12Fc mismatch complex (open circle). Pulse amplitude, 50 mV pulse width, 50 ms pulse period, 200 ms. Other conditions are the same as those in Fig. 12. 

As mentioned, DPV is particularly useful to determine accurately the formal electrode potentials of partially overlapping consecutive electron transfers. For instance, Figure 40 compares the cyclic voltammogram of a species which undergoes two closely spaced one-electron oxidations with the relative differential-pulse voltammogram. As seen in DPV the two processes are well separated. 

Figure 23 Cyclic and differential pulse voltammograms recorded at a platinum electrode in a CH2Cl2solution of [ l, 3,5- C=CRu(rj-C Hs)(PPh3)2 3 C6H3], Supporting electrolyte [NBu4][PF6] (0.2 mol dm 3). Scan rates (a) 0.2 Vs-1 (b) 0.004 V s f...

Figure 3.4 Differential pulse voltammograms with correction of background current for (a) 0.4 mM ascorbic acid, (b) 0.4 mM ascorbic acid + 0.05 mM dopamine, and (c) 0.4 mM ascorbic acid + 0.05 mM dopamine + 0.05 mM uric acid at a multiwalled carbon nanotube-ionic liquid/GC electrode. The total weight of the gel on the multiwalled carbon nanotube-ionic liquid modified electrode is 0.1 mg. Scan rate = 20 mVs. (Reprinted from Zhao, Y., Gao, Y., Zhan, D., Liu, H., Zhao, Q., Kou, Y., Shao, Y., Li, M., Zhuang, Q., and Zhu, Z., Talanta, 51-57, 2005. Copyright 2005 Elsevier. With permission.)...

This is illustrated in Fig. 2.4, where the deconvolution of differential pulse voltammograms at the glassy carbon electrode in the ethanol extract from two commercial inks are shown. Samples were taken from paper fragments of 0.10 mg immersed for 10 min in a 50 50 (v/v) ethanol 0.50 M aqueous acetate buffer (pH 4.85) solution. 

Figure 8.3 Differential pulse voltammograms of C76, C78, and C84 (tetrachloroethane + 0.1 M (w-Bu)4NPF6), using a GCE carbon electrode working and ferrocene/ferrocenium (Fc/Fc +) couple as an internal reference. Reprinted with permission from Ref. 7. Copyright 1995 American Chemical Society.

Figure 6.17 Differential-pulse voltammograms for the ferrocenyl naphthalene diimide indicator at the fiTlVmodified electrode before (curve a) and after (curve b) hybridization with dA2o- Also shown is the chemical structure of the indicator. (Reproduced with permission from Ref. 72.)...

Fig. 14.22. Differential pulse voltammogram of GO and FAD on a gold electrode, a, Background current b, after 10 min adsorption of the enzyme from 5.3 iM solution c, after 40 min d, after 120 min e, electrochemical response of adsorbed FAD measured in pure buffer after 2 hr adsorption from 10 iM FAD solution and washing the electrode. (Reprinted from A. Szucs, G. D. Hitchens, and J. O M. Bockris, Bioelectrochemistry 21 133, copyright 1989. Reproduced with permission of Elsevier Science.)...

Figure 3. Differential pulse voltammogram of a mixture of dibenzothiophene and benzothiophene in acetonitrile. Supporting electrolyte 0.1 M tetraethylammonium perchlorate. Indicator electrode glassy carbon disk, rotated at 1800 rpm. Linear potential ramp, 0.002 volt/s. Pulse amplitude, AE = 0.025 V. Pulse duration, 57 ms. Current sampling time, 17 ms.

Moreover, natural nucleic acids give rise to two well-separated oxidation peaks in differential pulse voltammograms, which can be used to probe individual adenine-thymine (AT) and guanine-cytosine (GC) pairs in double helical DNA during its conformational changes [38]. Differences in signals obtained at carbon electrodes were observed according to whether, or not, the DNA was denatured [39]. 

Some similar features were observed concerning the adsorption and electrochemical oxidation of DNA on glassy carbon and tin oxide electrodes [68]. Differential pulse voltammograms were recorded in buffer solution without DNA after adsorption of DNA onto the electrode surface during a predetermined time at a fixed potential suggesting the possibility of using adsorption to preconcentrate DNA on solid electrode surfaces and use this DNA-modified electrode for analytical purposes. 

Fig. 3.S. Successive differential pulse voltammograms of the glassy carbon electrode with dsDNA adsorbed, immersed in the ssDNA solution during modification s.e. = supporting electrolyte pH 4.5 acetate buffer 0.1 M. Pulse amplitude 50 mV, pulse width 70 ms, scan...

Fig. 3.8. Differential pulse voltammograms of I mM guanosine 5 -monophosphate in 0.2 M acetate buffer (a) Bare glassy carbon electrode 1 - s.e. 2, 3, 4 - first, second and third scans in the guanosine solution 5-IOth scan 6-20th scan (b) DNA-modified glassy carbon electrode I - s.e. 2. 3. 4 - first, second and third scans in the guanosine solution. Pulse amplitude 50 mV. pulse width 70 ms. scan rate 5 mV s. s.e.=supporting electrolyte.

Fig. 7-46- Differential pulse voltammogram recorded at a platinum electrode on a MeCN solution of [NiL ] ". Scan rate 0.005 Vs pulse amplitude 10 mV (reproduced by permission of the American Chemical Society).

Fig. 13 Differential pulse voltammograms of pyridoxine hydrochloride at the glassy carbon electrode obtained by adding successive aliqouts (0.1 ml) of an aqueous solution (O.IM) of the vitamin to pH 4 citric acid as the supporting electrolyte.

As mentioned, the electroactive bases in dsDNA are on the inside of the double helix and their distance and accessibihty to the electrode surface are determinant for nucleic acids electrochemical behaviour. In Figs. 4.3 and 4.4 some differential pulse voltammograms obtained with dsDNA and ssDNA at a glassy carbon electrode are presented. 

Fig. 20.8. Differential pulse voltammograms for 2,3,4-butanethiolate (C4) and 1,5,6,7-hexanethiolate (C6) Au MPCs as a function of uniform core size, in 0.05 M Hex4NCl04/ toluene/acetonitrile (2/1 v v), at 9.5 x 10 cm Pt electrode DC potential scan 10 mV s pulse amplitude 50 mV. Concentrations...

Figure 3.39 Differential pulse voltammograms of Co2FTF4 adsorbed on a graphite electrode in aqueous solutions pH =8 in the absence (solid curve a) and in the presence of 1 mM N-methyl imidazole (NMI) (dashed curve b) and 10mM NMI (dotted curve c).

Fig. 4. (A) Relationship between the concentration of human IgG and the peak current of the gold reduction process. (B) Differential pulse voltammograms recorded from 1.25 to 0.0V, for human IgG concentrations between 2.5 x 10 and 1 gg/ml. Electrode preconditioning 1,25V for 120 s deposition potential 1.25V for 150 s step potential 10mv amplitude 50 mv scan rate 33mv/s (vs. Ag/AgCI reference electrode).

Lead azide, Pb(N3)2, can be analysed by voltammetry, oxidizing azide ions at a carbon paste electrode and reducing lead ions at a dropping mercury electrode at pH 4.6 in an acetate buffer solution. Lead azide is poorly soluble in a pure aqueous solution, but can be dissolved when acetate ions are present. In Fig.l7 a differential pulse voltammogram for the determination of azide at a carbon paste electrode is shown. Some results from the analysis of lead azide are given in Table 7. 

Figure 7. Differential pulse voltammograms obtained for oxidation of 5 iM NO on a carbon fiber electrode (a) and carbon fiber electrode covered with polymeric porphyrin (TMHPP)Ni and Nation (b).

Fig. 6.2 a Schematic representation of ssDNA and dsDNA immobilized on the carbon electrode and b differential pulse voltammograms baseline corrected of (- - -) 5 pM 8-oxoGua or 2,8-oxoAde, ( ) 60 pg/mL ssDNA and (—)... 

Oxidation of NO on classical conductive materials such as noble metals (platinum, gold, etc.) or carbon, which are used as electrodes, produces a relatively low current at neutral pH. This is due to a strong absorption of NO to the electrode surface and a slow rate of electron transfer between NO and the electrode. Typical differential pulse voltammograms (DPV) of NO on carbon liber covered with Nafion, and carbon fiber covered with porphyrinic film and Nafion are shown in Fig. 3. There is about a 190 mV difference between the oxidation potential of NO on carbon fiber and porphyrinic film. A concentration of 0.1-pM NO produces a very small current on the carbon fiber electrode operating in the DPV mode (Fig. 3a). However, this same carbon fiber covered with a layer of polymeric porphyrin produces a much larger current (Fig. 3b) for NO oxidation. The current generated on polymeric porphyrin is mass transport controlled and is linearly proportional to the concentration of NO. The linearity is observed over four orders of magnitude of NO concentration [45]. 

Fig. 7.9 (a) Differential pulse voltammograms for a zeolite-modified electrode (ZME) after deposition of 1 ppm Ag" solution for different pre-concentration times (a) 1 (b) 2 (c) 3 (d) 5 (e) 10 min (Reproduced from Ref. [132] with permission of Elsevier), (b) Cyclic voltammograms of 2 X lO " M (a) dopamine and (b) ascorbic acid at (1) pure and (2) 10 wt.% zeolte-modified carbon paste electrodes (Reproduced from Ref. [133] with the permission of Elsevier)... 

Fig. 14. Differential pulse voltammograms of T2 bacteriophage DNA at the pyrolytic graphite electrode in 0.2 M sodium acetate, pH 6.4. (A) native DNA (B) thermally denatured DNA. DNA was at the concentration of 0.3 mg/ml.

Fig. 15. Differential pulse voltammograms of tobacco mosaic virus protein at the paraffin wax-impregnated spectroscopic graphite electrode in 0.02 M sodium carbonate, pH 10.5. (A) Native protein (B) the protein denatured by 8 M urea. The protein was at the concentration of 0.1 mg/ml.

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