Electrochemical behavior of dithionite in formaldehyde aqueous solution and its analytical application

The electrochemical behavior and the analytical determination of dithionite after reaction with formaldehyde in aqueous solution is described. Alterna ting current voltammetric and cyclic voltammetric measurements were employe d to elucidate the mechanism of the electrode process, based on the adsorpt ion phenomena of the hydroxymethanesulfinate ion formed and their subsequen t irreversible oxidation on the mercury electrode surface. The reaction mak es possible the sensitive analytical determination of dithionite in a stabl e form using differential-pulse polarography. The linear range for the meas urements was from 3.2 x 10(-5) to 2.2 x 10(-3) mol L-1 dithionite with a de tection limit calculated as 1.95 x 10(-5) mol L-1 The reaction was shown to be useful to determine dithionite after stabilization in solution, showing its degradation process relative to different elapsed times after preparat ion of the aqueous solution.