Single Sweep Method

Sulfur concrete freezes like a metal casting. The surface forms a skin first. Once the skin is formed, no further work can be accomplished. It can be reheated within limits by radiant heat and further worked. A single-sweep method is most effective. 

Vogel, J. Single-sweep Method Progress in Polarography II, 429, ed. 

Vogel, J. (1962). Single Sweep Method in Progress in Polarography (P. 

In LSV usually a single-sweep procedure, the so-called impulse method, is applied with the result illustrated in Fig. 3.30. In the multi-sweep procedure, formerly called Kipp method, Fig. 3.31 is obtained, which shows the saw-tooth character of the sweep and a series of peak curves of increasing height caused by the growing drop surface. Exceptionally, use is made of a triangular sweep in the impulse method this variant of cyclovoltammetry is depicted in Fig. 3.32... 

Fig. 5.18 Potentiostatic methods (A) single-pulse method, (B), (C) double-pulse methods (B for an electrocrystallization study and C for the study of products of electrolysis during the first pulse), (D) potential-sweep voltammetry, (E) triangular pulse voltammetry, (F) a series of pulses for electrode preparation, (G) cyclic voltammetry (the last pulse is recorded), (H) d.c. polarography (the electrode potential during the drop-time is considered constant this fact is expressed by the step function of time—actually the potential increases continuously), (I) a.c. polarography and (J) pulse polarography...

Potential Sweep Method, In the transient techniques described above, a set of measurements of the potential for a given current or the current for a given potential is measured in order to construct the current-potential function, i = f(E). For example, the Tafel lines shown in Figure 6.20 were constructed from a set of galvanostatic transients of the type shown in Figure 6.18. In the potential sweep technique, i = f(E), curves are recorded directly in a single experiment. This is achieved by sweeping the potential with time. In linear sweep voltammetry, the potential of the test electrode is varied linearly with time (Fig. 6.23a). If the sweep rate is... 

Lu et al. have described a single sweep voltammetric method for the determination of chlorpromazine at carbon paste electrodes [176]. Powdered tablet was dissolved in and diluted to 100 mL with water, whereupon a 10 mL portion of the solution was mixed with 10 mL of acetate buffer solution (pH 5.3). This solution was then diluted to 100 mL. The solution was analyzed using an electrolytic cell equipped with a carbon paste working electrode, a reference saturated calomel electrode, and a platimun counter-electrode. The voltammogram was recorded by single sweep scanning from 0 to 1 V, with a scanning rate of 10 mV/sec. 

Cao and Zeng [52] used of an oscillopolarographic method for the determination and the electrochemical behavior of omeprazole. Portions of standard omeprazole solution were treated with 1 ml 1 M ammonia/ ammonium chloride at pH 8.9 and the solution was diluted with water to 10 ml. The diluted solution was subjected to single sweep oscillopolaro-graphy with measurement of the derivative reduction peak at —1.105 V versus saturated calomel electrode. The calibration graph was linear from 0.5 to 10 /iM omeprazole with a detection limit of 0.2 fiM. The method was applied to the analysis of omeprazole in capsules with recoveries of 100-118.6% and RSD of 6.78%. The electrochemical behavior of omeprazole at the mercury electrode was also investigated. 

The kind of voltammetry described in Sect. 4.2. is of the single-sweep type, ie., only one current-potential sweep is recorded, normally at a fairly low scan rate (0.1-0.5 V/min), or by taking points manually. Cyclic voltammetry is a very useful extension of the voltammetric technique. In this method, the potential is varied in a cyclic fashion, in most cases by a linear increase in electrode potential with time in either direction, followed by a reversal of the scan direction and a linear decrease of potential with time at the same scan rate (triangular wave voltammetry). The resulting current-voltage curve is recorded on an XY-recorder,... 

The electrochemical behavior of nimodipine was studied in ammonia buffer containing 10% (v/v) ethanol [8]. A single-sweep oscillopolaro-graphic method was then developed for nimodipine in tablets. The calibration graph (peak current at —0.73 V vs. concentration) was linear from 0.2 to 70 pM, and the detection limit was 10 pM. The same authors applied linear sweep voltammetry for the determination of nimodipine in tablets [9]. A reduction peak at —0.62V vs. the Ag/ACl reference... 

The most direct way of determining E° and hence AG° for an organic redox couple is by voltammetric methods, such as single-sweep voltammetry... 

The use of a potential-step technique such as cyclic staircase voltammetry represents a simple alternative to Ichise s method (j0 of obtaining information on both adsorption and electron transfer kinetics. The current decay immediately after a step is primarily capacitive while current at later times is almost totally due to electron transfer reactions. Thus, by measuring the current at several times during each step and by changing the scan rate, information on both the kinetics of the electrode process and the differential capacity can be obtained with a single sweep. 

A new polarographic analytical procedure that should prove useful in the direct analysis of RDX and HMX in admixts is described in Ref 88. This single-sweep technique is rapid and sensitive to about 50 parts-per-billion of either RDX or HMX alone or in admixt in natural w effluent. The method can also be used to analyze for... 

This is the mathematical basis for the interconversion of the FID, or time domain function g(t), and the absorption spectrum or frequency domain function g (o). This interconversion is known as a Fourier transform (FT). Although mathematically g(t) and g (o) are easily interconvertible, in practice obtaining an FID takes a much shorter time. For instance, a single sweep of a spectrum of width 10 Hz, aiming at a 1-Hz resolution, takes about 10 s with a continuous-wave instrument with the pulse method, an FID with the same degree of resolution is obtained in less than 1 s. 

Cyclic Voltammetry. In this method, the potential of the working electrode is varied linearly with time from an initial potential of E to a final value of f, and then reversed from Ef to E at the same rate, as shown in Fig. 4.3.15. The resulting current is measured as a function of time or potential. This scheme can be used as a single sweep or a multisweep, as used in cyclic voltaimnetry. The potential range is generally selected to suit the reaction under study. 

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