TAPPI T 419 om-18 describes the qualitative and the quantitative determination of unmodified starches and starches modified only by conventional oxidation techniques or enzyme conversion, which are used for beater addition or surface sizing.

This procedure measures the total starch content and does not differentiate between starch inside and on the surfaces of the paper.

Some starches that are cationic, substituted, grafted, or combined with resins are not within the scope of this procedure, because special techniques are required for them. Test to determine whether the starch is appropriate for this procedure by checking for extractability. If it can be extracted quantitatively and forms the iodine complex, it should be able to be determined by this method.

This method is applicable only for papers with fully bleached pulp, because lignin and lignin remnants can also react with iodine to form a color complex.