Determination of mercaptoacetic acid with potassium dichromate in the presence of potassium iodide by potentiometric and visual methods

Abstract

A potentiometric procedure for the assay of mercaptoacetic acid with potassium dichromate in the presence of potassium iodide is described. The oxidation of mercaptoacetic acid proceeds via the liberation of iodine from potassium iodide (added to the titration mixture) by the addition of potassium dichromate. Oxalic acid is used as the catalyst to accelerate the reaction between potassium iodide and potassium dichromate. Mercaptoacetic acid is also determined visually with potassium dichromate, using starch or naphthol blue-black as indicators.