Differential pulse voltammetry voltammograms

Despite these possible drawbacks, differential pulse voltammetry is one of today s most popular electroanalytical tools. Its principal advantages over normal pulse voltammetry are twofold (i) many analytes can be sampled with a single voltammogram since the analytical peaks for each analyte are quite well resolved, and (ii) by working with a differential current, and hence obtaining a voltammetric peak, the analytical sensitivity can be improved to about 5 x 10 to mol dm. This sensitivity is clearly superior to normal pulse voltammetry. 

An alternative and more recent electroanalytical tool is square-wave voltammetry (which is probably now employed more often than normal or differential pulse voltammetry). In this technique, a potential waveform (see Figure 6.26) is applied to the working electrode. Pairs of current measurements are then made (depicted on the figure as t and f2) these measurements are made for each wave period ( cycle ), which is why they are drawn as times after to (when the cycle started). The current associated with the forward part of the pulse is called /forward, while the current associated with the reverse part is /reverse- A square-wave voltammogram is then just a graph of the difference between these two... 

Always monitor the electrical transduction of DNA damage by differential pulse voltammetry (DPY). Between recording voltammo-grams always keep the working electrode at a standby potential of OY. Before recording a voltammogram use an equilibration time of 5 s. The experimental conditions for DPV are as follows pulse amplitude 50 mV, pulse width 70 ms and scan rate 5 mV s 1. 

Figure 10 Potential waveforms for normal pulse (NPV) and differential pulse voltammetry (DPV) displaying potential versus time (b), and a typical normal pulse and differential pulse voltammogram plotting current versus potential (a)...

Figure Bl.28.5. Applied potential-time waveforms for (a) normal pulse voltammetry (NPV), (b) differential pulse voltammetry (DPV), and (c) square-wave voltammetry (SWV), along with typical voltammograms obtained for each method.

FIGURE 25-30 Voltammogram for a differential-pulse voltammetry experiment. Here. A/ - - i. i (see Fig-... 

FIGURE 15.12 Cyclic voltammograms (a) and differential pulse voltammc rams (b) of 1 mgm DNA in a 0.1 M phosphate buffer (pH 7.4) at a bare GC electrode (i) and CNT-modified GC electrodes using CTAB (ii), Triton X-100 (iii), and SDS (iv) as dispersants. The inset in (b) shows a differential pulse voltam-mogram of Ipgml adenine in a 0.1 M phosphate buffer (pH 7.4) at the CNT/CTAB-modified GC electrode. Accumulation time 5min. The scan rate of cyclic voltammetry is 0.1 Vs . The pulse amplitude of differential pulse voltammetry is 50 mV, and the pulse width is 50 ms (unpublished results). 

Single-fiber sensors and catheter-protected sensors can operate in an amperometric or voltammetric mode. In both methods a current proportional to NO concentration is measured. Of the several voltammetric methods available, differential pulse voltammetry (DPV) is most suitable for the measurement of NO. In DPV, a potential modulated with rectangular pulses is linearly scanned from 0.4 to 0.8 V. The resulting voltammogram (alternating current versus voltage plot) contains a peak due to NO oxidation. The peak current should be observed at a potential of 0.63-0.67 V which depends on the pulse amplitude. This potential is the characteristic potential for NO oxidation on Nafion coated porphyrinic sensor. 

Figure 13.11 (a) Cyclic voltammograms and (b) differential pulse voltammetry recorded for (1) NSPANl, (2) NSPANl/GR, (3) NSPANI/AuNP/GRl, (4) NSPANI/AuNP/GR,... 

Fig. 6 Differential pulse voltammetry (a) potential-time waveform sum of staircase and synchronized pulses and (b) schematic voltammogram.

Fig. 16. Differential pulse voltammetry. (A) Applied potential waveform. Circular inset shows one pulse enlarged currents ii and i2 measured just before and at end of pulse. (B) Differential pulse voltammogram 170 jjlM dopamine in pH 7.4 phosphate buffer, sweep rate 10 mV/sec. At in arbitrary units. Oxidation current is plotted downward in accord with standard electroanalytical conventions. Oxidative differential pulse voltammograms are frequently plotted with 180° rotation about the horizontal axes of Fig. 16B. One should always clearly label the type of current and direction of scan (oxidative) for all voltammetric figures. The oxidative direction of potential sweep should increase from right to left.

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