Temperature amperometry

Direct current (DC) amperometry is used for the analysis of catecholamines, phenols, and anilines, which are easy to oxidize. A single potential is applied, and the current is measured. The current resulting from the oxidation or reduction of analyte molecules is dependent on many factors, including the concentration of the analyte, temperature, the surface area of the working electrode, and the linear velocity of the flowing stream over the surface of the working electrode. 

In recent years, there has been a rapid growth in the number of publications that report the use of surfactant monomers or micelles to improve the analytical perfommice of various spectroscopic (UV-visible spectrophotometry, fluorimetry, phosphorimetry, chemiluminescence and atomic spectroscopy), and electrochemical (especially amperometry) methods [1]. The unique properties of surfactants have been recognized as being very helpful to overcome many problems associated with the use of organic solvents in these methods. Surfactant-modified procedures yield sensitivity and/or selectivity improvements in determinations commonly performed in homogeneous solution, whereas certain analytic methods (such as room-temperature phosphorescence in solution) can be exclusively conducted in organized media. 

In this chapter, the features of other detection methods that have been utilized in MLC conventional and sensitized fluorimetry, room-temperature phosphorimetry, inductively coupled plasma hyphenated with mass spectrometry, and amperometry, are examined. Table 12.1 gives details of some reported procedures. Most of them appeared during the 90s, when the development of applications in MLC increased. The study and use of new detection systems can result in enhanced flexibility and efficiency for the separation analyst. 

M. Tupin, C. Bataillon, J.P. Gozlan, P. Bossis, High temperature corrosion of Zircaloy-4 followed by in-situ impedance spectroscopy and chrono- amperometry. Effect of an anodic polarization, in Electrochemistry in Light Water Reactors Reference Electrodes, Measurement, Corrosion and Tribocorro- sion Issues (European Federation of Corrosion Publ. No. 49), ed. by R.-W. Bosch, D. Feron, J.-P. Celis (CRC Press, Boca RatonAVood- head/ Cambridge, UK, 2007), pp. 134-155... 

Figure 3.215 Isocratic separation of sugar alcohols, anhydrosugars, and mono- and disaccharides. Separator column Metrosep Carb 2 column dimensions 150 mm x 4 mm i.d. column temperature 45 °C eluent lOmmol/L NaOH flow rate 1 mL/min detection pulsed amperometry on a gold working electrode Injection volume lOOpL peaks 0.64 mg/L...

Figure 10.338 Separation of homocysteine and other physiological amino acids. Separator column OmnIPac PCX-500 column dimensions 250 mm x2 mm i.d. column temperature 30 °C eluent 0.15mol/L NaCIOV MeCN (95 5 v/v) + 19.7 mmol/L HCIO4 flow rate 0.25 mL/mln detection integrated pulsed amperometry on a gold working...

Figure 10.392 Separation of free and total glycerol in a B100 biodiesel sample derived from soy. Separator column CarboPac MAI column dimensions 250mm x4 mm i.d. column temperature 30°C eluent lOOmmol/L NaOH flow rate 0.4mLymin detection pulsed amperometry on a gold working electrode injection volume 5 pL samples (a) B100 biodiesel (soy) after water extraction and (b)...

Fig. 7-19. Separation of ampicillin utilizing integrated amperometry with a multicyclic pulse sequence in comparison with UV detection. - Separator 150 mm X 4 mm i.d. Vydac C8 (208TP5451) column temperature 30°C eluant ...

Fig. 9-158. Analysis of cephapirin and ampicillin in a milk extract utilizing integrated amperometry. - Separator column 150 mm x 4.6 mm i.d. Luna C-8 (Phenomenex, USA) column temperature 30°C eluant 0.1 mol/L acetate buffer — acetonitrile (96 4 v/v), pH 3.75 detection integrated amperometry on a gold working electrode sample (a) milk extract spiked with 40 pg/L cephapirin (1) and 20 pg/L ampicillin (2),...

First of aU, the meaning of the terms amperometry and voltammetry should be pointed out, owing to more and more widely diffused mismatch. Amperometry (= measurement of a current) simply indicates whatever technique in which a current is measured. It is measured as a function of an independent variable that, in electroanalysis/electrochemistry is reasonably the corresponding electrode potential or time in principle, however, all possible experimental variables are plausible. Measuring a current as a function of temperature, or of pressure, or even of the gravity force, constitutes in aU cases an amperometric measurement. 

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