T 2035 (OTTO) Trichloroacetic acid, 98% Cas 76-03-9 - used to precipitate protein. T 2035 (OTTO) Trichloroacetic acid, 98% Cas 76-03-9 - used to determine protein concentration by quantitative precipitation. T 2035 (OTTO) Trichloroacetic acid, 98% Cas 76-03-9 - used as decalcifier and fixative in microscopy.