Colorimetric Determination of Formaldehyde Using 1,3-Diphenyl-2-thiohydantoin and Sodium Hydroxide

A method for the determination of formaldehyde concentration in water is described. It is based on a coupling reaction of 1,3-diphenyl-2-thiohydantoin with formaldehyde. In this reaction an anionic pigment is formed by addition of sodium hydroxide solution. The color intensity and formaldehyde concentrations were linearly related in the range up too 100 ώM. The minimum detectable concentration was 2 ώM. The precision (R.S.D.) was 3.62%.