Organic voltammetric analysis

The determination of hydroperoxide number is significant because of the adverse effect of hydroperoxides on certain elastomers in the fuel systems. This method (ASTM D-6447) measures the same peroxide species, primarily the hydroperoxides in diesel fuel. This test method does not use the ozone-depleting substance l,l,2-trichloro-l,2,2-trifluoroethane (ASTM D-3703) and is applicable to any water-insoluble, organic fluid, particularly gasoline, kerosene, and diesel fuel. In this method, a quantity of sample is contacted with aqueous potassium iodide (KI) solution in the presence of acid. The hydroperoxides present are reduced by potassium iodide, liberating an equivalent amount of iodine, which is quantified by voltammetric analysis. 

In passing it should be noted that voltammetric analysis is also very useful for determining many of the typical cure components used in the engineering adhesives. Thus, organic peroxides, aromatic amines, substituted hydrazines, thiols, etc., may also be determined at the mercury electrode. 

D. Daniel, I.G.R. Gutz, Microfluidic cell with a Ti02-modified gold electrode irradiated by an UV-LED for in situ photocatalytic decomposition of organic matter and its potentiality for voltammetric analysis of metal ions Bectrochem. Commun. 2007, 9, 522-528. 

In the following part of this paper I am going to present a system of organic electroactive groups or of substances which can be subjected to voltammetric analysis at solid electrodes forming thus a base for construction of electrochemical detectors in HPLC. Since electroactivity is the most important property of the substance to be studied and we are interested here only in the analytical properties, i.e. in the characteristical potentials (Ep or Ep and in the shape of the i - E or ip - E plot it will be not necessary to stress Adams observatlon[7] "Electrochemistry of organic oxidations is mainly the chemistry of follow-up reactions" (of course, similar ideas hold true with reductions). Nevertheless, electroactivity will be discussed here jointly with probable or proved interpretations of mechanisms. This is done in contrast to Bond s view[9] who considers interpretations of electrode processes and of their follow-up or preceding reaction useless in analytical chemistry. 

Anatoliy Aleksandrovich Kaplin (October 20, 1937-July 27, 1989) (Fig. 5.4.3.4) has developed SV for the determination of traces in semiconductor and other high-purity materials [51]. He was an excellent organizer, not only of research work (he has supervised 20 PhD theses) but also of conferences, e.g., of four All-Union Conferences on Stripping Voltammetry in Tomsk (1973,1982,1986,1990) under the chairmanship of Stromberg. Parallel to Ye. Ya. Neyman who worked in Moscow, Kaplin started to study the formation of complex amalgams, intermetaUic compounds in mercury, and solid solutions under the conditions of SV. Anodic currents of such systems were described by Kaplin on the basis of regular solution thermodynamics. Kaplin defended his doctoral thesis entitled Inverse voltammetric analysis of microsamples, crystal layers and films before a conunission in Moscow. 

Tonle IK, Ngameni E, Walcarius A (2005) Preconcentration and voltammetric analysis of mercury(II) at a carbon paste electrode modified with natural smectite-type clays grafted with organic chelating groups. Sensor Actuat B 110 195-203... 

Almost all of the methods described in Chapter 23 can be used for in vivo analyses, both voltammetric and potentiometric ones. The former are used primarily in the analysis of organic substances, which, within certain ranges of potential, can be either oxidized or reduced. Another popular method is the amperometric determination of oxygen in different biological media with the Clark electrode (Section 23.3). 

Apart from acidification, UV irradiation is the only preliminary preparative step in voltammetric determinations it may be required to degrade organic substances binding trace metals in the form of inert complex species. The analysis of samples from natural waters may be significantly affected by the binding capacity of such dissolved organic substances. 

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