diffusion current residual current
How it works? A The applied voltage is gradually increased, ty pically by going to a more positive( more negative decomposing potential) Asmall residual current is observed A When the voltage becomes great enough, reduction occurs at the analytical electrode causing a current A The electrode is rapidly saturated so current production is limited -based on diffusion of the analyte to the small electrode
How it works? ▲ The applied voltage is gradually increased, typically by going to a more positive( more negative decomposing potential) ▲ A small residual current is observed. ▲ When the voltage becomes great enough, reduction occurs at the analytical electrode causing a current. ▲ The electrode is rapidly saturated so current production is limited – based on diffusion of the analyte to the small electrode
How it works The reduced species alters the surface of the mercury electrode To prevent problems, the mercury surface is renewed by“ knocking off” a drop- providing a fresh surface This results in an oscillation of the data as it is collected
How it works ? The reduced species alters the surface of the mercury electrode. To prevent problems, the mercury surface is renewed by “ knocking off ” a drop –providing a fresh surface. This results in an oscillation of the data as it is collected
Polarographically quantitative analytical methods ODirect comparison method Ift, m, D and n are constant, then we can simplify things by using a standard Then STD STD C UNK UNK
●Direct comparison method Polarographically quantitative analytical methods If t, m, D and n are constant, then we can simplify things by using a standard. Then UNK STD d d C C i i UNK STD =
Wave height of polarographic wave is determined easier than peak current, so following equation is in more common use C STD STD UNK UNK
Wave height of polarographic wave is determined easier than peak current, so following equation is in more common use UNK STD C C h h UNK STD =