Medical brain notes 35

  Shape of Voltammograms The   shape   of   a   voltammogram   is   determined   by   several   experimental   factors,   the most   important   of   which   are   how   the   current   is   measured   and   whether   convection is   included   as   a   means   of   mass   transport.   Despite   an   abundance   of   different   voltam- metric   techniques,   only   three   shapes are   common   for   voltammograms   (Figure   11.33). The   voltammogram   in   Figure   11.33a   is   characterized   by   a   current   that   increases from   the   background   residual   current   to   a   limiting   current   at   potentials   at   which the  ...

  Quantitative and Qualitative Aspects of Voltammetry Earlier   we   described   a   voltammogram   as   the   electrochemical   equivalent   of   a   spec- trum   in   spectroscopy.   In   this   section   we   consider   how   quantitative   and   qualitative information may be extracted from a voltammogram. Quantitative information is obtained   by   relating   current   to   the   concentration   of   analyte   in   the   bulk   solution. Qualitative   information   is   obtained   from   the   voltammogram   by   extracting   the  standard-state   potential   for   the   redox   reaction.   For   simplicity   we   only   consider voltammograms   similar   to   that   shown   in   Fi...

  Voltammetric Techniques A   number   of   voltammetric   experiments   are   routinely   used   in   quantitative   and  qualitative  analyses. Several  of  these methods  are  briefly described  in   this  section. Polarography   The   earliest   voltammetric   experiment   was   normal   polarography   at a   dropping   mercury   electrode.   In   normal   polarography   the   potential   is   linearly scanned,   producing   voltammograms   such   as   that   shown   in   Figure   11.35.   Although polarography   takes   place   in   an   unstirred   solution,   a   limiting   current   is   obtained because   the   falling   Hg   drops   mix   the   solution...