Voltammetry adsorptive stripping voltammetr

Stripping voltammetry has also been applied to the quantitation of the drug in formulations. A sensitive and precise method using square-wave adsorptive stripping voltammetry has been developed for the determination of sulpha-quinoxaline in veterinary formulations [157]. The differential pulse adsorptive stripping voltammetric determination of midazolam in injectable formulations as a method for quality control has been demonstrated [158]. 

Stripping Voltammetry One of the most important quantitative voltammetric techniques is stripping voltammetry, which is composed of three related techniques anodic, cathodic, and adsorptive stripping voltammetry. Since anodic strip-... 

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]. 

Microfluidic chip devices are also shown to be attractive platforms for performing microscale voltammetric analysis and for integrating voltammetric procedures (linear-sweep, square-wave and adsorptive-stripping voltammetry) with on-chip chemical reactions and fluid manipulations [97]. 

Voltammetric procedures can be used for trace measurements of diltiazem. Diltiazem exhibits both reductive and oxidative voltammetic responses. Adsorptive stripping voltammetry can be used due to the reductive capacity of diltiazem. The adsorptive stripping is accomplished with a static mercury drop electrode in conjunction with a stripping analyzer. A detection... 

Adsorptive stripping voltammetry (ASV) is another specialised technique where the SMDE electrode is used for reducible species and carbon paste electrodes for oxidisable ones. This allows enrichment (by factors of 100-1000) of ions at the working electrode before stripping them off for measurement this improves the detection limits. This technique is rapid, sensitive (10 "M), economical and simple for trace analysis. The basic instrumentation for stripping analysis is apotentiostat (with voltammetric analyser), electrode and recorder. While voltammetry is generally very useful for compounds that do not have a chromophore or fluorophore, stripping analysis is the best analytical tool for direct, simultaneous determination of metals of environmental concern, e.g. lead, cadmium, zinc and copper in sea water. 

Pertcchnetatc and Tc(lV) could be more sensitively analyzed in acidic media in the presence of thiocyanate by adsorption stripping voltammetry at the hanging mercury drop electrode using the differential pulse mode. Determinations down to 5-fO " g Te per ml were feasible. An intense eurrent signal at -1.32 V vs SCE was observed if only technetium and thiocyanate were present in the solution. Larger quantities of salts, e.g. chlorides and sulphates, decreased the sensitivity of the method considerably. This, however, could easily be avoided if, after electrodeposition was completed, the primary electrolyte was replaced by a pure solution of dilute acid for the stripping voltammetric step [100]. 

In this study low concentration of timolol are determined by adsorptive stripping voltammetry. The preconcentration of the analyte is done by adsorption of the drug on a surface of the electrode and the adsorbed species are determined by application of a voltammetric scan on the electrode. This technique has recently been employed by different authors for the determination of a number of drugs. 

The adsorption of ions and molecules on the surface of mercury electrodes is a thoroughly investigated phenomenon [51 ]. Surface-active substances are either electroactive [52] or electroinactive [53]. The former can be analyzed by adsorptive stripping voltammetry [54]. This is the common name for several electroanalytical methods based on the adsorptive accumulation of the reactant and the reduction, or oxidation, of the adsorbate by some voltammetric technique, regardless of the mechanisms of the adsorption and the electrode reaction [55, 56]. Frequently, the product of the electrode reaction remains adsorbed to the electrode surface. Hence, the term stripping should not be taken literally in all cases. Besides, some adsorbates may be formed by electrosorption reactions, so that their reduction includes covalently bound mercury atoms. The boundary between adsorption followed by reduction, on the one hand, and electrosorption, on the other, is not strictly defined. Moreover, it is not uncommon that, upon cathodic polarization, the current response is caused by a catalytic evolution of hydrogen, and not by the reduction of the adsorbate itself [57]. However, what is common to all methods is a hnear relationship between the surface concentration of the adsorbate and the concentration of analyte at the electrode surface ... 

Bobrowski, A., Krolicka, A., and Lyczkowska, E. (2008) Carbon paste electrode plated with lead film. Voltammetric characteristics and application in adsorptive stripping voltammetry. Electroanalysis, 20, 61 -67. 

Improved sensor respraise to several organic species can be achieved by exploiting the high adsorption capability of carbon surfaces, in adsorptive stripping voltammetry (AdSV). This procedure, based on very similar principles of solid phase microextraction (SPME), implies that analytes are pre-concentrated at carbon nanostructured surfaces prior to voltammetric detection. It has been successfully... 

In adsorptive stripping voltammetry (AdSV) metal chelates and organic molecules are accumulated by adsorption at the surface of the working electrode. If these compounds are electrochemically active, i.e., if they are reducible or oxidizable. their subsequent voltammetric determination is possible. By this principle of so-called adsorptive stripping voltammetry, organic and organomet-allic compounds are determined in the ultra-trace range. This technique is particularly important for the trace analysis of metals that are not readily deposited as the element on mercury electrodes... 

Square-wave voltammetry (SWV) is one of the four major voltammetric techniques provided by modern computer-controlled electroanalytical instruments, such as Autolab and pAutolab (both EcoChemie, Utrecht), BAS 100 A (Bioana-lytical Systems) and PAR Model 384 B (Princeton Applied Research) [1], The other three important techniques are single scan and cyclic staircase, pulse and differential pulse voltammetry (see Chap. II.2). All four are either directly applied or after a preconcentration to record the stripping process. The application of SWV boomed in the last decade, firstly because of the widespread use of the instruments mentioned above, secondly because of a well-developed theory, and finally, and most importantly, because of its high sensitivity to surface-confined electrode reactions. Adsorptive stripping SWV is the best electroanalytical method for the determination of electroactive organic molecules that are adsorbed on the electrode surface [2]. 

The adsorption of ions and molecules on the surface of mercury electrodes is a thoroughly investigated phenomenon [51]. Surface-active substances are either electroactive [52], or electroinactive [53]. The former can be analyzed by adsorptive stripping voltammetry [54]. This is the common name for several elec-troanalytical methods based on the adsorptive accumulation of the reactant and the reduction, or oxidation, of the adsorbate by some voltammetric technique. 

The strong adsorption of organic molecules occurring at carbon surfaces can be exploited to improve the sensitivity of the sensor response toward several organic species analytes can be pre-concentrated at carbon nanostructured surfaces in advance to the actual voltammetric detection, following an approach very similar to Solid Phase MicroExtraction (SPME). This analytical procedure, called Adsorptive Stripping Voltammetry (AdSV) has been applied for the detection of electroactive species of interest in the environmental field, such as herbicides or nitro-derivatives. Thanks to the occurrence of mechanisms similar to those... 

Adsorptive stripping voltammetry is similar to conventional stripping voltammetry in that the analyte is preconcentrated onto the working electrode prior to the voltammetric measurement. However, it differs from the conventional scheme in the approach used to preconcentrate the analyte. Unlike the electrolytic process employed in conventional stripping voltammetry, adsorptive accumulation (that does not include any faradaic process) forms the basis for adsorptive stripping voltammetry. 

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