Differential normal pulse voltammetry

A variant of double-pulse voltammetry is the DNPV or differential normal pulse voltammetry, where at the end of each pulse an additional small constant pulse is imposed63 . 

Tacussel and their application by Gonon et al.148 to differential pulse voltammetry (DPV) and differential normal pulse voltammetry (DNPV) in vivo, also called the biopulse technique the microelectrodes are implanted in the living animal brain and variations in the concentrations of some molecules can be followed via the Tacussel PRG 5 and BIPAD instruments (see also the selection of commercial models in Table 3.4). 

Figure 5.12 Excitation signal for differential normal pulse voltammetry. [Adapted from Ref. 42.]...

Although multiple electrochemical techniques exist, those used in freely moving animals are chronoamperometry, differential normal-pulse voltammetry, and fast-scan cyclic voltammetry. Excellent comparisons between these can be found in literature, particularly Troyer et al.[5,7,30] and Robinson el al.[8] and therefore will not be diskussed here. 

Differential normal pulse voltammetry. As presently used, in this waveform each pulse corresponding to NPV (see Fig. 5a) is divided into two equal parts with a small increase in potential in the second half of the pulse. The difference between the currents sampled halfway through and at the end of the main pulse is displayed as a function of the potential of the first half of the pulse. Advantages relative to DPV are that less time is spent at potentials in which adsorption and so on can occur. 

Fig. 9. A potential-time waveform for differential normal pulse voltammetry (a) and resulting current-potential curves (b).

Fig. 7. Effect of an NO-synthase inhibitor (L-arginine p-nitroanilide) on the differential normal pulse voltammetry measurements obtained at a carbon fiber/[(H20)Fe PWii039] -doped poly(Af-methyl pyrrole)/Nafion microelectrode in the rat brain. Electrochemical recording between 0.4 and 1.35 V (vs. Ag/AgCl) at 10 mVs with one cycle every 2 min. The indicated potential corresponds to the oxidation peak of NO and the zero time indicates the injection of the inhibitor into the rat. (From [150].)...

Gonon FG, Navarre F, Buda MJ (1984) In vivo monitoring of dopamine release in the rat brain with differential normal pulse voltammetry. Anal Chem 56 573-575... 

The realization that current sampling on a step pulse can increase the detection sensitivity by increasing the faradaic/charging ratio is the basis for the development of various pulse voltammetric (or polarographic) techniques. Also, the pulses can be applied when it is necessary and can reduce the effect of diffusion on the analyte. Figure 18b. 11 shows the waveform and response for three commonly used pulse voltammetric techniques normal pulse voltammetry (NPY), differential pulse voltammetry (DPV), and square-wave voltammetry (SWV). 

Fig. 18b.11. Figures show the pulse waveform and response for three techniques (a) normal pulse voltammetry (NPV), (b) differential pulse voltammetry (DPV), and (c) square-wave voltammetry (SWV).

In many respects, differential pulse voltammetry is more similar to classical polarography than to the normal pulse methods (see above). A linear potential ramp of dE/dt is applied to the working electrode (see Figure 6.24). However, in common with normal pulse voltammetry, a succession of pulses are also applied to the working electrode. (The WE is often a DME, and then we refer to differential pulse polarography .)... 

In normal pulse voltammetry, the current is sampled for a short period just before the drop is dislodged. The current monitored is assumed to be constant with time. In the differential pulse method, the current is monitored twice per drop the first sample is taken just before the rise in potential when the pulse starts, while the second is taken at the end of the current pulse just before it decreases back to the baseline. The difference between these two currents is Alpuise The differential pulse voltammogram is then a plot of current difference against potential. In... 

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. 

Alternative voltammetric methods that improve the sensitivity of voltammetry as an electroanalytical tool are normal pulse voltammetry (with a lower detection limit of 10 mol dm ), differential pulse voltammetry (with a detection limit of 10 -10 mol dm ) and square-wave pulse voltammetry (with a detection limit which is perhaps as low as 10 mol dm ). 

Large-amplitude ( normal ) pulse voltammetry techniques were introduced in Chapter 3. The differential normal pulse (DNP) method combines several features of both the small- and large-amplitude pulse techniques. This technique is normally performed at a DME and is actually a form of polarography. The... 

In addition to the traditional SEV techniques discussed earlier, various pulse volt-ammetric techniques have been employed at solid electrodes in molten salts, especially in the room-temperature haloaluminate melts. Numerous pulse techniques have been devised, and some of the more common examples of this family of volt-ammetric methods are described in Chapters 3 and 5 of this volume. However, the application of these methods to molten salts is limited primarily to large amplitude pulse voltammetry (LAPV), differential-pulse voltammetry (DPV), and, more recently, reverse normal-pulse voltammetry (RNPV). The application of LAPV and... 

Equation (4.77) corresponds to the normal mode of Differential Double Pulse Voltammetry for which the duration of the second applied pulse is not restricted as in the case of DDPV [35]. From this equation, the expression of the current A/dndpv at very negative and positive potentials valid for any electrode geometry can be directly obtained,... 

Osakai et al. used a microcomputer-controlled system for the ion transfer voltammetry procedure [20]. The system used is based on a NEC PC-9801 microcomputer, which was designed by using a polarizable oil-water interface as an ion-selective electrode surface. The system was applied to the determination of acetylcholine ion by cyclic, differential pulse, and normal pulse voltammetry at the PVC-nitrobenzene gel electrode. The amperometric measurement was carried out with voltage pulses of short durations and constant amplitude. 

See -> differential pulse voltammetry, - normal pulse voltammetry, and -> reverse pulse voltammetry. 

Pulse voltammetry — A technique in which a sequence of potential pulses is superimposed to a linear or staircase voltage ramp. The current is usually measured at the end of the pulses to depress the - capacitive (charging) current. Depending on the way the pulses are applied and the current is sampled we talk about - normal pulse voltammetry, reverse pulse voltammetry and - differential pulse voltammetry. Several other, less popular pulse techniques are offered in commercial voltammetric instrumentation. Some people consider - square-wave voltammetry as a pulse technique. 

We will consider five subtopics tast polarography and staircase voltammetry, normal pulse voltammetry, reverse pulse voltammetry, differential pulse voltammetry, and square wave voltammetry. Tast polarography, normal pulse voltammetry, and differential pulse voltammetry form a sequence of development rooted historically in polarography at the DME. To illustrate the motivating concepts, we will introduce each of these methods within the polarographic context, but in a general way, applicable to both the DME and SMDE. Then we will turn to the broader uses of pulse methods at other electrodes. Reverse pulse voltammetry and square wave voltammetry were later innovations and will be discussed principally outside the polarographic context. 

The range of time scales for the differential pulse experiment is the same as for normal pulse voltammetry, hence a given system ordinarily shows the same degree of reversibility toward either approach. However, the degree of reversibility toward pulse methods may differ from that shown toward conventional polarography for reasons discussed in Section 7.3.2. 

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